Evidence-based effects and studies
Detailed analysis of research findings
In a randomized 14-day crossover trial, caffeinated coffee increased ventricular ectopy and daily steps and reduced nightly sleep duration versus avoiding caffeine, with no significant change in atrial ectopy.
Acute caffeine (3 mg/kg) improved muscular velocity, power and endurance across sexes, with larger effects in lower-body (back squat) at moderate–high loads.
In preterm infants (<32 weeks), early prophylactic caffeine reduced duration of oxygen therapy and other respiratory support needs compared with therapeutic (delayed) caffeine.
Prophylactic acetaminophen + caffeine given before spinal anesthesia reduced frequency and severity of post-dural puncture headache and increased maternal satisfaction vs placebo.
Acute caffeine (3 mg/kg) alone improved muscular endurance, velocity and power (esp. back squat); co-ingestion with sodium bicarbonate did not produce additive benefit and attenuated caffeine's ergogenic effect.
Oral caffeine (100 or 200 mg three times daily) after laparoscopic colectomy did not shorten time to first bowel movement or improve colonic transit compared with placebo.
In healthy aeromedically fit pilots, a single 300 mg dose of caffeine at midnight reduced the nighttime decline in psychomotor performance after extended wakefulness.
IV or enteral caffeine given in delivery room was feasible; most infants had measurable caffeine blood levels but respiratory outcomes matched historical controls.
Acute 3 mg/kg caffeine improved peak and mean power in repeated Wingate sprints in both sexes with sex‑specific timing differences (males early sprints, females later sprints).
In fasted young adults, combined caffeine (75 mg) + glucose (75 g) improved sustained attention and verbal memory consolidation beyond either substance alone; caffeine alone improved simple reaction time.
In a double-blind trial, 65 mg caffeine in coffee improved some working memory tasks (especially in extraverts) and sped simple reaction time and encoding.
A 2 mg/kg dose of caffeine made people react faster, detect more targets, and encode new information faster compared with placebo/withdrawal.
Caffeine improved reaction time during administration and a conditioned context elicited similar improvement when placebo was given.
In a double-blind trial, 65 mg caffeine in coffee improved some working memory tasks (especially in extraverts) and sped simple reaction time and encoding.
In a double-blind trial, 65 mg caffeine in coffee improved some working memory tasks (especially in extraverts) and sped simple reaction time and encoding.
Forty mg caffeine delivered in chewing gum improved mood and sustained-attention task performance (faster encoding) compared with placebo or no gum in young adults.
In middle-aged women, 12 weeks of Zumba improved postural balance and cognition; adding 100 mg/day caffeine with Zumba produced improvements in postural balance and cognitive tests in challenging conditions.
Over 6 weeks of resistance training, a caffeinated multi-ingredient pre-workout (≈406 mg caffeine) produced similar body composition, muscle thickness, and performance changes as an isocaloric carbohydrate comparator; waist circumference decreased in the PREW group.
In a randomized placebo-controlled crossover (200 mg caffeine), caffeine reduced several EEG band powers (alpha1/alpha2 and beta) with some differences between early-phase psychosis patients and healthy controls.
A multi-ingredient caffeine supplement did not change strength or cycling time-to-exhaustion in untrained men.
56 male sprinters randomized to control, caffeine, TMR, or both; caffeine and TMR reduced reaction times, TMR improved anaerobic/neuromuscular measures, and combined treatment slightly raised heart rate.
In moderate caffeine consumers tested while deprived, caffeine improved sustained attention and alertness; these benefits were not seen when participants were not caffeine-deprived, consistent with withdrawal-reversal.
In a randomized single-blind crossover in healthy adults, caffeinated carbonated beverage produced faster and more frequent improvements in sustained attention and increased self-rated energy vs control; caffeine (carbonated or not) improved accuracy and reaction time vs control.
In sleep-deprived healthy men, caffeinated (vs decaffeinated) coffee raised post-OGTT glucose and insulin and increased fasting insulin and insulin resistance (HOMA), indicating worse glucose homeostasis under these conditions.
Over 12 weeks, Zumba training improved functional performance in middle-aged women; daily 100 mg caffeine alone also produced improvements and combining caffeine with Zumba led to the largest gains in mobility, lower-body endurance, and walking speed.
Across two crossover studies in habitual low–moderate consumers tested without enforced caffeine restriction (combined N≈56), oral caffeine (2.5 or 6 mg/kg) did not change time-to-exhaustion, perceived fatigue, perceptual or affective responses, or time perception.
Post-hoc analysis of a randomized crossover trial (placebo vs ~98 mg caffeine) showing that individual trait mental/physical energy and fatigue modify caffeine's effects on mood, cognitive (serial subtraction) and fine-motor (9‑hole peg) performance—people with higher trait fatigue often gained more benefit.
Randomized double-blind crossover in recreational males showed dose-dependent benefits of caffeine mouth rinse on selective attention: faster completion time with 300 mg, fewer errors with 150 mg, and reduced perceived difficulty at 150 and 300 mg vs placebo.
Caffeine given immediately after birth to very preterm infants increased respiratory effort measures versus later administration.
Single 6 mg/kg caffeine increased blood pressure and tidal volume and raised plasma caffeine concentrations; epinephrine rose in able-bodied and paraplegic but not tetraplegic participants, with limited HRV changes.
Acute caffeine (50–450 mg) produced stimulant-like effects: increased blood pressure and arousal, improved vigilance, but worsened short-term memory in light nondependent users.
Single 200 mg caffeine given overtly or covertly to healthy adults; large within-person variability in PK measures but no average covert vs overt difference.
In a randomized single-blind crossover in healthy adults, caffeinated carbonated beverage produced faster and more frequent improvements in sustained attention and increased self-rated energy vs control; caffeine (carbonated or not) improved accuracy and reaction time vs control.
In 52 healthy female students, a single serving of standardized Turkish coffee (≈3 mg/kg caffeine) produced acute changes in subjective energy, concentration and sleep scores, reduced heart rate over time versus control, and was associated with reductions in fasting blood sugar at some post‑drink time points.
In elite jiu-jitsu athletes, 3 mg/kg caffeine increased throws in later SJFT sets, raised heart rate slightly, improved strength/endurance perception, and reduced fatigue perception, but did not change technical actions during real combat.
Participants given 200 mg caffeine showed better convergent problem-solving but no change in creative idea generation or working memory.
Large case–control analysis found no clear evidence that maternal caffeine intake increases risk of cardiovascular birth defects.
Forty mg caffeine delivered in chewing gum improved mood and sustained-attention task performance (faster encoding) compared with placebo or no gum in young adults.
In a crossover RCT including people with or at risk for glaucoma, one cup of caffeinated coffee (182 mg) produced small but statistically significant increases in intraocular pressure (IOP), ocular perfusion pressure and ocular pulse amplitude at 60–90 min vs decaffeinated coffee.
In hemodialysis patients, drinking regular versus decaffeinated coffee during sessions did not change the incidence of dialysis‑related headache or hypotension over 12 sessions.
Drinking three cups/day of lightly roasted (higher polyphenols and caffeine) or regular coffee for 12 weeks reduced body fat percentage and increased muscle mass in overweight/obese adults; lightly roasted coffee produced a slightly greater fat percentage reduction.
An 8-week randomized trial of an herbal mix (includes 240 mg/day caffeine) produced greater short-term weight and fat loss but more withdrawals and side effects.
Across three small experiments, caffeine reduced subjective drowsiness but produced mixed effects on subjective effort and no consistent performance improvements.
Caffeine increased self-rated alertness, jitteriness, and blood pressure in healthy adults; theanine opposed caffeine's blood pressure rise.
In partially sleep-deprived healthy volunteers an acute energy shot improved multiple composite cognitive measures and self-rated alertness for up to 6 hours compared with placebo.
Caffeine plus heat exposure increased body and skin temperatures and amplified thermogenesis-related biomarkers (FGF‑21 and irisin).
A single 60 mg oral dose of caffeine improved sustained attention, reaction times, and subjective alertness in middle-aged healthy adults.
Reducing caffeine intake in pregnancy (moderate reduction) did not change babies' birth weight or length of gestation.
In well-trained cyclists, caffeine in a performance bar improved time to exhaustion and complex cognitive task performance during and after prolonged exercise.
In healthy young adults, a 100 mg caffeine capsule had no overall effect on smell tests, but non-habitual caffeine users showed higher odour sensitivity and worse odour identification after caffeine; small mood trends were seen in habitual users.
Across two small crossover experiments, caffeinated beverages acutely stimulated autonomic measures (blood pressure, skin conductance), altered heart rate and skin temperature, and increased energetic arousal, with some dose‑dependent physiological effects.
In healthy young men, 300 mg caffeine taken before moderate aerobic exercise delayed parasympathetic heart-rate recovery and slowed blood pressure return to baseline, without changing HR, respiratory rate or oxygen saturation.
In 21 resistance‑trained participants, a caffeinated multi‑ingredient pre‑workout produced small, non‑significant increases in some concentric force measures (more evident in males) and modest subjective increases in energy/focus versus placebo, but overall supplements did not clearly outperform placebo.
In 21 active men, 5 mg/kg caffeine taken 1 h before repeated sprint running modestly improved fastest sprint time but increased fatigue and elevated heart rate and blood lactate.
In healthy adults, coffee (0, 200, 400 mg caffeine) transiently changed BIA-derived body composition measures after ~30–70 min, but changes were independent of caffeine dose and likely due to water intake.
Both actual caffeine and the expectation of having had caffeine improved attention and psychomotor speed; expectation alone improved self-reported vigor and reward responsivity.
In healthy older adults, a caffeinated coffee dose (~3 mg/kg) produced limited effects on balance metrics and did not change functional physical performance measures.
In rested young male habitual caffeine consumers, individualized morning caffeine doses reduced fatigue and improved simple and sustained attention and the executive updating domain, independent of meal ingestion.
In 58 adult females given 100 mg caffeine vs placebo after 24-h caffeine abstinence, no differences were found in acoustic or aerodynamic voice measures 30 minutes post-ingestion.
In 29 healthy adults given sham low or high caffeine doses, belief/expectation did not change choice reaction time or 10 km running performance.
Evening 200 mg caffeine worsened objective sleep: longer time to fall asleep, lower sleep efficiency and shorter total sleep time in both age groups.
Caffeinated coffee improved encoding of new information and reduced fatigue over the morning, but raised blood pressure and pulse; breakfast improved mood and some memory measures.
Realistic multi-dose caffeine intake (4×65 mg) and a single 200 mg dose both increased alertness and anxiety and improved several task-performance measures.
Repeated coffee mouth-rinses (dose-related) increased futsal-specific endurance distance and improved/accelerated recovery of vertical jump performance versus control.
In a crossover pilot trial with a caffeine active control, caffeine improved post-lunch rapid visual information processing and some multitasking measures versus placebo.
In a large balanced placebo crossover, both caffeine (300 mg) and expectancy produced similar subjective effects (energy, reduced sleepiness); placebo altered caffeine pharmacokinetics.
High-dose caffeine (8 mg/kg) increased maximal strength in bench press, deadlift, and squat and raised plasma Ca2+ compared with placebo or lower dose.
Ingesting 6 mg/kg caffeine increased reported neutral, positive and negative effects versus placebo; obese women reported more adverse effects (e.g., urine output, increased vigor, headaches) 1 hour after ingestion.
In healthy young women, caffeine alone improved working memory accuracy at ~T2 and combined tDCS+caffeine improved working memory accuracy (T1 and T2) and Stroop accuracy (T1) versus sham; caffeine alone did not improve inhibitory control and neither intervention affected cognitive flexibility.
200 mg caffeine reduced lower-alpha (alpha1, 8–10 Hz) power primarily in participants with higher habitual caffeine consumption; overall caffeine effects did not differ reliably across menstrual phases.
In women with urinary incontinence, reducing fluid intake improved some symptoms, but switching from caffeinated to decaffeinated drinks did not improve urinary symptoms.
Repeated exposure to a novel caffeinated-flavoured drink while not caffeine-deprived did not produce later increased liking when subjects were caffeine-deprived; liking increased only when drinks were consumed while deprived and contained caffeine.
In 42 trained cyclists, 6 mg/kg caffeine improved ~30‑min time‑trial performance versus placebo and control; correct identification of caffeine further increased the observed benefit.
A single cup of coffee (80 mg caffeine) produced a small rise in systolic BP but overall no statistically significant effect on BP at one hour in healthy young adults.
In tactical males, 300 mg caffeine and a 150 mg caffeine + methylliberine + theacrine combo similarly improved vigilance reaction time; caffeine raised DBP vs placebo while the combo raised SBP but not DBP.
In 165 healthy men and women across age/hormonal-status groups, acute caffeine increased systolic and diastolic blood pressure by a few mmHg.
In a randomized 14-day crossover trial, caffeinated coffee increased ventricular ectopy and daily steps and reduced nightly sleep duration versus avoiding caffeine, with no significant change in atrial ectopy.
In a randomized, double-blind, placebo-controlled trial, caffeine (2–4 mg/kg) improved 10-km cycling time overall but effects were strongly modified by CYP1A2 genotype (benefit in AA, harm in CC).
Acute coffee and anhydrous caffeine before testing produced small improvements: coffee improved leg-press 1RM versus anhydrous caffeine, and caffeine attenuated reductions in sprint power/total work versus placebo.
Large randomized trial in very low birth-weight infants: caffeine reduced bronchopulmonary dysplasia (oxygen use at 36 weeks) and shortened positive airway pressure duration, with transiently reduced early weight gain and no increase in death or brain injury.
In healthy aeromedically fit pilots, a single 300 mg dose of caffeine at midnight reduced the nighttime decline in psychomotor performance after extended wakefulness.
Repeated nighttime caffeine gum improved objective performance during 50 h wakefulness but did not change overall self-reported sleepiness or fatigue.
Bright light combined with 100 mg caffeine gum improved driving performance and subjective sleepiness more than caffeine alone in sleep-restricted young drivers.
In 40 young adults, 36 h sleep deprivation impaired temporal (recency) memory; a single 350 mg caffeine dose reduced subjective sleepiness but did not restore temporal memory performance.
In sleep-deprived adults, stimulants had different effects: caffeine improved alertness measures but did not enhance cartoon humor appreciation.
Caffeine, naps, and especially their combination improved alertness and vigilance in laboratory and field night-shift settings.
In PD outpatients, 100 mg/day caffeine adjuvant (2×50 mg/day) for 3 weeks was associated with substantial motor improvement (UPDRS III) compared to placebo, though some patients reported transient side effects.
A bioactive combination including caffeine increased resting metabolic rate (thermogenesis) in men, and propranolol (beta-blocker) reduced about half of that thermogenic response.
Acute 3 mg/kg caffeine improved peak and mean power in repeated Wingate sprints in both sexes with sex‑specific timing differences (males early sprints, females later sprints).
NaHCO3 and caffeine each improved some aspects of repeated-sprint performance, but their coingestion did not produce a synergistic benefit.
In healthy elderly adults, 6 mg/kg caffeine increased plasma epinephrine, free fatty acids, and lactate (percent increases consistent at rest, 5 min, and exhaustion), and increased insulin-resistance measures.
In fasted young adults, combined caffeine (75 mg) + glucose (75 g) improved sustained attention and verbal memory consolidation beyond either substance alone; caffeine alone improved simple reaction time.
In 40 adults randomized to ~216 mg caffeine vs placebo, pattern‑reversal VEP P100 latency and amplitude measured at baseline and 1 h post‑dose were unchanged after caffeine.
Over 6 weeks of resistance training, a caffeinated multi-ingredient pre-workout (≈406 mg caffeine) produced similar body composition, muscle thickness, and performance changes as an isocaloric carbohydrate comparator; waist circumference decreased in the PREW group.
In obese adults after weight loss, rye bread enriched with green tea extract (providing ~123–158 mg caffeine/day) did not improve weight-loss maintenance but was associated with slightly better blood pressure control and a marginally smaller waist circumference.
A multi-ingredient product (including caffeine and ephedrine) produced modest additional weight loss (~1.5 kg) and greater reductions in BMI and waist circumference versus placebo over 12 weeks; no BP or pulse increases were observed.
In a randomized placebo-controlled crossover (200 mg caffeine), caffeine reduced several EEG band powers (alpha1/alpha2 and beta) with some differences between early-phase psychosis patients and healthy controls.
In this large prospective cohort of postmenopausal women, total caffeine intake (and coffee/tea consumption) was not associated with risk of sudden cardiac death.
56 male sprinters randomized to control, caffeine, TMR, or both; caffeine and TMR reduced reaction times, TMR improved anaerobic/neuromuscular measures, and combined treatment slightly raised heart rate.
In a crossover trial comparing guarana, caffeine (5 mg/kg) and placebo, caffeine showed no clear improvement in reaction time or memory versus placebo but did prevent post-exercise increases in simple reaction time variability.
A single 60 mg oral dose of caffeine improved sustained attention, reaction times, and subjective alertness in middle-aged healthy adults.
In regular caffeine consumers tested when fatigued, repeated low doses of caffeine improved subjective mood/alertness and enhanced several performance measures, with dose‑dependent effects.
Resistance-trained men completed multiple caffeine and placebo trials; caffeine often increased arousal and dynamic muscle-power measures but effects varied across repeated trials.
Active adults performed cycling in normoxia and simulated altitude after 6 mg/kg caffeine; caffeine did not improve exercise capacity but changed some physiological and perceptual responses during steady-state.
Two experiments showed 5 mg/kg caffeine increased knee-extensor strength and motor-unit recruitment and improved leg-cycling time-trial performance while reducing pain and perceived effort in some conditions.
In moderate caffeine consumers tested while deprived, caffeine improved sustained attention and alertness; these benefits were not seen when participants were not caffeine-deprived, consistent with withdrawal-reversal.
In sleep-deprived healthy men, caffeinated (vs decaffeinated) coffee raised post-OGTT glucose and insulin and increased fasting insulin and insulin resistance (HOMA), indicating worse glucose homeostasis under these conditions.
Over 12 weeks, Zumba training improved functional performance in middle-aged women; daily 100 mg caffeine alone also produced improvements and combining caffeine with Zumba led to the largest gains in mobility, lower-body endurance, and walking speed.
Across two crossover studies in habitual low–moderate consumers tested without enforced caffeine restriction (combined N≈56), oral caffeine (2.5 or 6 mg/kg) did not change time-to-exhaustion, perceived fatigue, perceptual or affective responses, or time perception.
Post-hoc analysis of a randomized crossover trial (placebo vs ~98 mg caffeine) showing that individual trait mental/physical energy and fatigue modify caffeine's effects on mood, cognitive (serial subtraction) and fine-motor (9‑hole peg) performance—people with higher trait fatigue often gained more benefit.
Randomized double-blind crossover in recreational males showed dose-dependent benefits of caffeine mouth rinse on selective attention: faster completion time with 300 mg, fewer errors with 150 mg, and reduced perceived difficulty at 150 and 300 mg vs placebo.
Randomized double-blind placebo-controlled parallel trial in surgeons/attendees (n=107) found no significant effect of caffeinated coffee (≈230 mg from 340 mL) vs decaffeinated coffee on laparoscopic simulator performance (fine motor dexterity).
Caffeine given immediately after birth to very preterm infants increased respiratory effort measures versus later administration.
Acute caffeine (50–450 mg) produced stimulant-like effects: increased blood pressure and arousal, improved vigilance, but worsened short-term memory in light nondependent users.
Single 200 mg caffeine given overtly or covertly to healthy adults; large within-person variability in PK measures but no average covert vs overt difference.
In a randomized single-blind crossover in healthy adults, caffeinated carbonated beverage produced faster and more frequent improvements in sustained attention and increased self-rated energy vs control; caffeine (carbonated or not) improved accuracy and reaction time vs control.
In 201 healthy volunteers, acute caffeine (200 mg added to decaf coffee) increased blood pressure and calculation speed overall; CYP1A2 genotype (rs762551 CC) showed larger systolic BP rise in low habitual consumers (≤90 mg/day).
In 52 healthy female students, a single serving of standardized Turkish coffee (≈3 mg/kg caffeine) produced acute changes in subjective energy, concentration and sleep scores, reduced heart rate over time versus control, and was associated with reductions in fasting blood sugar at some post‑drink time points.
Among 162 caffeine-using smokers in cessation programs, continuing caffeine use after quitting raised plasma caffeine to ~203% of baseline by 3 weeks; abstainers reported transient increased fatigue and decreased stimulation but cessation rates were similar.
In elite jiu-jitsu athletes, 3 mg/kg caffeine increased throws in later SJFT sets, raised heart rate slightly, improved strength/endurance perception, and reduced fatigue perception, but did not change technical actions during real combat.
Participants given 200 mg caffeine showed better convergent problem-solving but no change in creative idea generation or working memory.
In trained male CrossFit athletes, caffeine combined with active tDCS reduced execution time in a Clean & Jerk time-trial; caffeine or tDCS alone did not produce significant effects on average.
High-dose caffeine (8 mg/kg) increased maximal strength in bench press, deadlift, and squat and raised plasma Ca2+ compared with placebo or lower dose.
In a crossover RCT including people with or at risk for glaucoma, one cup of caffeinated coffee (182 mg) produced small but statistically significant increases in intraocular pressure (IOP), ocular perfusion pressure and ocular pulse amplitude at 60–90 min vs decaffeinated coffee.
Caffeine plus heat exposure increased body and skin temperatures and amplified thermogenesis-related biomarkers (FGF‑21 and irisin).
In trained male CrossFit athletes, caffeine combined with active tDCS reduced execution time in a Clean & Jerk time-trial; caffeine or tDCS alone did not produce significant effects on average.
In trained male CrossFit athletes, caffeine combined with active tDCS reduced execution time in a Clean & Jerk time-trial; caffeine or tDCS alone did not produce significant effects on average.
Double-blind randomized placebo-controlled crossover in 52 taekwondo athletes (elite and sub-elite) showed that 3 mg/kg caffeine acutely improved agility and kicking performance and reduced session RPE, with effects varying by sex and competitive level.
In healthy young adults, a 100 mg caffeine capsule had no overall effect on smell tests, but non-habitual caffeine users showed higher odour sensitivity and worse odour identification after caffeine; small mood trends were seen in habitual users.
In 21 active men, 5 mg/kg caffeine taken 1 h before repeated sprint running modestly improved fastest sprint time but increased fatigue and elevated heart rate and blood lactate.
A 5 mg/kg dose of caffeine increased cycling time-to-exhaustion in both users and nonusers, with larger and longer-lasting effects in nonusers.
Both actual caffeine and the expectation of having had caffeine improved attention and psychomotor speed; expectation alone improved self-reported vigor and reward responsivity.
In healthy older adults, a caffeinated coffee dose (~3 mg/kg) produced limited effects on balance metrics and did not change functional physical performance measures.
In rested young male habitual caffeine consumers, individualized morning caffeine doses reduced fatigue and improved simple and sustained attention and the executive updating domain, independent of meal ingestion.
In 48 male volleyball players, 4-week supplementation plus resistance training showed that combined Rhodiola + caffeine improved jump power and reduced perceived exertion more than either supplement or placebo.
5 mg/kg caffeine improved ~30-min cycling time-trial performance and modestly altered physiological responses in trained male cyclists.
In 28 light caffeine consumers, caffeine altered some alcohol-related cognitive performance measures and increased subjective stimulation without reducing absolute perceived intoxication.
Caffeine (6.5 mg/kg) improved total repetitions in resistance training compared with placebo in active women; no additional benefit from combining with carbohydrate rinse.
Evening 200 mg caffeine worsened objective sleep: longer time to fall asleep, lower sleep efficiency and shorter total sleep time in both age groups.
After 26 h wakefulness, caffeine did not worsen recovery or next-night sleep compared with placebo.
Caffeinated coffee improved encoding of new information and reduced fatigue over the morning, but raised blood pressure and pulse; breakfast improved mood and some memory measures.
Realistic multi-dose caffeine intake (4×65 mg) and a single 200 mg dose both increased alertness and anxiety and improved several task-performance measures.
Caffeinated coffee increased alertness and psychomotor performance in people with colds (restoring them to healthy levels); decaffeinated coffee also produced improvements.
In a randomized crossover trial, a 75 mg caffeine positive-control produced consistent alerting and performance-enhancing effects versus placebo in healthy adults (n=72).
In children who habitually consume caffeine, a 50 mg dose after overnight abstinence restored cognitive accuracy, prevented withdrawal headache, and increased alertness; non/low-consumers showed no clear benefit.
Single 600 mg slow-release caffeine decreased calmness and prolonged sleep onset but did not change alertness the next day.
In 379 participants, caffeine (100 mg then 150 mg) increased anxiety in genetically susceptible individuals (ADORA2A rs5751876 TT) especially among low habitual consumers; habitual consumption reduced anxiogenic response (tolerance) and no net alerting benefit was seen in some groups.
In 80 healthy volunteers, a 200 mg caffeine active control increased subjective alertness and affected cardiovascular measures.
In 24 adults, an 80 mg‑caffeine energy drink increased self-rated alertness and reduced depression scores; combining it with alcohol did not alter blood alcohol or subjective intoxication versus alcohol alone.
In a 54.5 h total sleep deprivation trial with 50 adults, a single 600 mg caffeine dose maintained performance and alertness relative to placebo, comparable to effective modafinil doses.
Repeated coffee mouth-rinses (dose-related) increased futsal-specific endurance distance and improved/accelerated recovery of vertical jump performance versus control.
In a crossover pilot trial with a caffeine active control, caffeine improved post-lunch rapid visual information processing and some multitasking measures versus placebo.
Ingesting coffee providing 3 mg/kg caffeine improved 5 km cycling time (~9 s faster, ≈1.9% vs placebo) in both men and women.
Caffeinated coffee (3 mg/kg) improved 5-km cycling time (~8 seconds) and habitual caffeine intake level did not modify this ergogenic effect.
Ingesting coffee providing 3 mg/kg caffeine improved 5 km cycling time (~9 s faster, ≈1.9% vs placebo) in both men and women.
In a large balanced placebo crossover, both caffeine (300 mg) and expectancy produced similar subjective effects (energy, reduced sleepiness); placebo altered caffeine pharmacokinetics.
High-dose caffeine (8 mg/kg) increased maximal strength in bench press, deadlift, and squat and raised plasma Ca2+ compared with placebo or lower dose.
Ingesting 6 mg/kg caffeine increased reported neutral, positive and negative effects versus placebo; obese women reported more adverse effects (e.g., urine output, increased vigor, headaches) 1 hour after ingestion.
In healthy young women, caffeine alone improved working memory accuracy at ~T2 and combined tDCS+caffeine improved working memory accuracy (T1 and T2) and Stroop accuracy (T1) versus sham; caffeine alone did not improve inhibitory control and neither intervention affected cognitive flexibility.
200 mg caffeine reduced lower-alpha (alpha1, 8–10 Hz) power primarily in participants with higher habitual caffeine consumption; overall caffeine effects did not differ reliably across menstrual phases.
Acute caffeine (3 mg/kg) improved muscular velocity, power and endurance across sexes, with larger effects in lower-body (back squat) at moderate–high loads.
In preterm infants (<32 weeks), early prophylactic caffeine reduced duration of oxygen therapy and other respiratory support needs compared with therapeutic (delayed) caffeine.
Prophylactic acetaminophen + caffeine given before spinal anesthesia reduced frequency and severity of post-dural puncture headache and increased maternal satisfaction vs placebo.
Acute caffeine (3 mg/kg) alone improved muscular endurance, velocity and power (esp. back squat); co-ingestion with sodium bicarbonate did not produce additive benefit and attenuated caffeine's ergogenic effect.
Oral caffeine (100 or 200 mg three times daily) after laparoscopic colectomy did not shorten time to first bowel movement or improve colonic transit compared with placebo.
In 29 patients with panic disorder and 53 healthy controls (n=82), 150 mg caffeine did not increase subjective anxiety but did raise physiological arousal (SCR), increase costly avoidance behavior, and impair exteroceptive attention.
In preterm infants (n=78) comparing high-dose versus lower-dose caffeine citrate, there was no difference in frequency or days with apnoea; side-effect rates showed non-significant trends toward being higher with the higher dose.
IV or enteral caffeine given in delivery room was feasible; most infants had measurable caffeine blood levels but respiratory outcomes matched historical controls.
In older adults (42) and Parkinson's patients (24) who abstained from caffeine for a week, a single 100 mg caffeine dose improved response selection (accuracy) on choice reaction and Stroop tasks, sped Stroop RTs, improved dual-task (RSVP) performance via better T1 identification but impaired single-task RSVP performance; effects did not differ by disease.
In a cohort of infants of Latina mothers followed to 18–36 months (106 children with follow-up), days when children consumed caffeine were associated with higher calorie intake and lower intake of key nutrients; the educational intervention did not prevent overweight.
In 37 healthy adults undergoing total sleep deprivation with crossover acute caffeine/placebo, acute caffeine improved PVT reaction time, but higher habitual caffeine intake (>50 mg/day) was associated with worse vigilant attention (longer RT) and lower individual alpha frequency (IAF).
In 201 healthy volunteers, acute caffeine (200 mg added to decaf coffee) increased blood pressure and calculation speed overall; CYP1A2 genotype (rs762551 CC) showed larger systolic BP rise in low habitual consumers (≤90 mg/day).
A single caffeinated energy shot acutely raised systolic and diastolic blood pressure, but these elevations were not sustained after repeated daily use; ECG intervals were unchanged.
In 100 male undergraduates, both actual caffeine and the expectation of caffeine affected mood and performance; caffeine increased BP, pulse, and reduced fatigue.
Higher doses of caffeine (500 mg vs 100 mg) increased ambulatory systolic and diastolic blood pressure and heart rate during the workday.
Managers deprived of their usual caffeine showed withdrawal discomfort and decreased performance on several complex task measures.
Over 14 days, an ephedra‑caffeine weight‑loss product produced no significant changes in measured cardiovascular parameters versus placebo in healthy overweight adults.
In patients undergoing EPS, oral caffeine (5 mg/kg) increased systolic and diastolic blood pressure but did not affect cardiac conduction parameters or SVT inducibility.
In patients with familial LQTS, an energy drink containing caffeine acutely raised blood pressure and in some individuals caused large QTc prolongation.
Single 6 mg/kg caffeine increased blood pressure and tidal volume and raised plasma caffeine concentrations; epinephrine rose in able-bodied and paraplegic but not tetraplegic participants, with limited HRV changes.
In 110 men, acute caffeine raised systolic and diastolic blood pressure modestly (~+4 mmHg and +3 mmHg) and increased plasma adrenaline.
In overweight patients, a 6-week ephedrine (20 mg) plus caffeine (200 mg) treatment produced modest blood pressure reductions in some groups, heart-rate increase in normotensives, weight loss across groups, and frequent side-effects.
56 male sprinters randomized to control, caffeine, TMR, or both; caffeine and TMR reduced reaction times, TMR improved anaerobic/neuromuscular measures, and combined treatment slightly raised heart rate.
In 52 healthy female students, a single serving of standardized Turkish coffee (≈3 mg/kg caffeine) produced acute changes in subjective energy, concentration and sleep scores, reduced heart rate over time versus control, and was associated with reductions in fasting blood sugar at some post‑drink time points.
Caffeine in hot drinks produced dose-dependent autonomic/cardio responses (e.g., changes in heart rate, blood pressure and baroreflex measures) during ingestion.
In 7- to 9-year-old children, moderate caffeine lowered heart rate and raised blood pressure during rest and low-moderate exercise but did not change VO2 or RER.
In healthy children, low–moderate caffeine doses raised preexercise blood pressure and lowered heart rate by ~5–6 bpm; metabolic measures were largely unchanged.
Higher doses of caffeine (500 mg vs 100 mg) increased ambulatory systolic and diastolic blood pressure and heart rate during the workday.
Over 14 days, an ephedra‑caffeine weight‑loss product produced no significant changes in measured cardiovascular parameters versus placebo in healthy overweight adults.
One cup of caffeinated espresso acutely raised blood pressure and heart rate but did not change QTc in healthy adults.
In a double-blind crossover study of 23 mildly overweight adults, an acute multi-ingredient supplement containing high caffeine did not change heart rate or blood pressure but reduced RER in low-caffeine users.
Over 8 weeks, the caffeine arm showed no statistically significant changes in vital signs or routine lab safety measures compared with other groups.
In healthy young men, 300 mg caffeine taken before moderate aerobic exercise delayed parasympathetic heart-rate recovery and slowed blood pressure return to baseline, without changing HR, respiratory rate or oxygen saturation.
A single 500 mg caffeine dose in habitual coffee drinkers raised ambulatory blood pressure by ~4/3 mmHg, lowered heart rate by ~2 bpm, and increased urinary free epinephrine by ~32%, amplifying stress-related cardiovascular responses.
In overweight patients, a 6-week ephedrine (20 mg) plus caffeine (200 mg) treatment produced modest blood pressure reductions in some groups, heart-rate increase in normotensives, weight loss across groups, and frequent side-effects.
In middle-aged women, 12 weeks of Zumba improved postural balance and cognition; adding 100 mg/day caffeine with Zumba produced improvements in postural balance and cognitive tests in challenging conditions.
Over 6 weeks of resistance training, a caffeinated multi-ingredient pre-workout (≈406 mg caffeine) produced similar body composition, muscle thickness, and performance changes as an isocaloric carbohydrate comparator; waist circumference decreased in the PREW group.
In a randomized placebo-controlled crossover (200 mg caffeine), caffeine reduced several EEG band powers (alpha1/alpha2 and beta) with some differences between early-phase psychosis patients and healthy controls.
Crossover trial in active young adults: 6 mg/kg caffeine acutely improved reaction time but did not change attention or memory and increased some side effects.
Caffeine increased blood pressure; expectancy/placebo effects influenced subjective alertness in one experiment, while reaction time showed no consistent change.
In 48 habitual caffeine consumers deprived 24 h, caffeine (200 mg) improved aspects of cognition and reduced fatigue; taurine and glucose had different or no effects.
In a randomized double-blind placebo-controlled trial (n=60) a citicoline-caffeine beverage improved sustained attention, reaction time, and working memory measures and increased P300 amplitudes on EEG vs placebo.
In a crossover trial comparing guarana, caffeine (5 mg/kg) and placebo, caffeine showed no clear improvement in reaction time or memory versus placebo but did prevent post-exercise increases in simple reaction time variability.
A multivitamin–mineral product with guarana improved decision-making speed for about 30–90 min and maintained parasympathetic HRV measures during the first hour compared with caffeine alone or placebo.
Healthy young adults who regularly use caffeine got 200 mg caffeine plus varied CBD doses; self-reported drug effects and anxiety did not change.
In moderate caffeine consumers tested while deprived, caffeine improved sustained attention and alertness; these benefits were not seen when participants were not caffeine-deprived, consistent with withdrawal-reversal.
In sleep-deprived healthy men, caffeinated (vs decaffeinated) coffee raised post-OGTT glucose and insulin and increased fasting insulin and insulin resistance (HOMA), indicating worse glucose homeostasis under these conditions.
Over 12 weeks, Zumba training improved functional performance in middle-aged women; daily 100 mg caffeine alone also produced improvements and combining caffeine with Zumba led to the largest gains in mobility, lower-body endurance, and walking speed.
Across two crossover studies in habitual low–moderate consumers tested without enforced caffeine restriction (combined N≈56), oral caffeine (2.5 or 6 mg/kg) did not change time-to-exhaustion, perceived fatigue, perceptual or affective responses, or time perception.
200 mg caffeine (chewing gum) did not significantly alter paired-pulse TMS measures of short-interval intracortical inhibition in healthy adults.
Caffeine given immediately after birth to very preterm infants increased respiratory effort measures versus later administration.
Acute caffeine (50–450 mg) produced stimulant-like effects: increased blood pressure and arousal, improved vigilance, but worsened short-term memory in light nondependent users.
Double-blind crossover in active males given ~5 mg/kg/day caffeine for 4 days: caffeine did not change resting, total, or physical-activity energy expenditure or accelerometer-measured activity patterns.
In healthy active adults, single doses of thermogenic drinks with 100–140 mg caffeine increased resting metabolic rate; the 140 mg formula also increased resting fat oxidation, with no clear effects on exercise fat oxidation or VO2max.
Randomized, placebo-controlled trial in 80 men: acute pre-exercise 3 mg/kg caffeine improved 3-km running time and Wingate mean power output across groups; habitual caffeine use attenuated ergogenicity.
Phase III double-blind randomized trial in dental pain: ibuprofen 400 mg + caffeine 100 mg provided superior and faster analgesia versus ibuprofen alone, caffeine alone, and placebo over 8 h with acceptable tolerability.
Randomized double-blind crossover in trained judoists: acute 6 and 9 mg/kg caffeine improved judo-specific performance (throws) and increased heart rate; habitual caffeine consumers were less responsive.
In 150 healthy adults, a drink with 40 mg caffeine + 60 g glucose improved overall multi-tasking performance and speed on some tasks versus placebo or glucose alone, without changing mood.
In 32 well-trained collegiate sprinters/jumpers, very low (1 mg/kg) to moderate (3–6 mg/kg) caffeine doses improved vertical jump performance, with 6 mg/kg producing significant enhancement.
In elite jiu-jitsu athletes, 3 mg/kg caffeine increased throws in later SJFT sets, raised heart rate slightly, improved strength/endurance perception, and reduced fatigue perception, but did not change technical actions during real combat.
Participants given 200 mg caffeine showed better convergent problem-solving but no change in creative idea generation or working memory.
Large case–control analysis found no clear evidence that maternal caffeine intake increases risk of cardiovascular birth defects.
Forty mg caffeine delivered in chewing gum improved mood and sustained-attention task performance (faster encoding) compared with placebo or no gum in young adults.
In healthy active adults, single doses of thermogenic drinks with 100–140 mg caffeine increased resting metabolic rate; the 140 mg formula also increased resting fat oxidation, with no clear effects on exercise fat oxidation or VO2max.
In hemodialysis patients, drinking regular versus decaffeinated coffee during sessions did not change the incidence of dialysis‑related headache or hypotension over 12 sessions.
Across three small experiments, caffeine reduced subjective drowsiness but produced mixed effects on subjective effort and no consistent performance improvements.
Caffeine increased self-rated alertness, jitteriness, and blood pressure in healthy adults; theanine opposed caffeine's blood pressure rise.
A single 60 mg oral dose of caffeine improved sustained attention, reaction times, and subjective alertness in middle-aged healthy adults.
In this pilot RCT, warm caffeinated coffee increased initial void volumes after catheter removal but did not change the proportion who spontaneously voided.
Reducing caffeine intake in pregnancy (moderate reduction) did not change babies' birth weight or length of gestation.
Acute caffeine raises blood pressure and five days of regular caffeine intake did not eliminate the BP response in about half of healthy adults.
In well-trained cyclists, caffeine in a performance bar improved time to exhaustion and complex cognitive task performance during and after prolonged exercise.
Controlled dosing over 11 days in healthy males showed no evidence that daily caffeine (up to 6 mg/kg/day) produced hypohydration or altered renal electrolyte measures compared with placebo.
In healthy young adults, a 100 mg caffeine capsule had no overall effect on smell tests, but non-habitual caffeine users showed higher odour sensitivity and worse odour identification after caffeine; small mood trends were seen in habitual users.
In a large randomized study, 200 mg caffeine given after overnight sleep loss restored vigilant attention (PVT) deficits but generally did not improve higher‑order placekeeping performance for most participants.
Across two small crossover experiments, caffeinated beverages acutely stimulated autonomic measures (blood pressure, skin conductance), altered heart rate and skin temperature, and increased energetic arousal, with some dose‑dependent physiological effects.
In 21 resistance‑trained participants, a caffeinated multi‑ingredient pre‑workout produced small, non‑significant increases in some concentric force measures (more evident in males) and modest subjective increases in energy/focus versus placebo, but overall supplements did not clearly outperform placebo.
In 21 active men, 5 mg/kg caffeine taken 1 h before repeated sprint running modestly improved fastest sprint time but increased fatigue and elevated heart rate and blood lactate.
Intravenous caffeine produced dose-dependent effects on brain imaging: intermediate dose (2.5 mg/kg) maximized BOLD activation increase; highest dose (5 mg/kg) maximized cerebral blood flow response.
In healthy adults, coffee (0, 200, 400 mg caffeine) transiently changed BIA-derived body composition measures after ~30–70 min, but changes were independent of caffeine dose and likely due to water intake.
Ingesting 6 mg/kg caffeine increased reported neutral, positive and negative effects versus placebo; obese women reported more adverse effects (e.g., urine output, increased vigor, headaches) 1 hour after ingestion.
Both actual caffeine and the expectation of having had caffeine improved attention and psychomotor speed; expectation alone improved self-reported vigor and reward responsivity.
In 48 male volleyball players, 4-week supplementation plus resistance training showed that combined Rhodiola + caffeine improved jump power and reduced perceived exertion more than either supplement or placebo.
In 28 light caffeine consumers, caffeine altered some alcohol-related cognitive performance measures and increased subjective stimulation without reducing absolute perceived intoxication.
In a randomized trial of 95 patients with urinary symptoms, an education intervention reduced caffeine intake and produced significant improvements in urinary urgency and frequency at one month.
In a population survey and a controlled blinded experiment (57 regular users enrolled), abrupt caffeine withdrawal produced symptomatic withdrawal in a subset (e.g., headaches/tiredness), whereas gradual withdrawal produced minimal symptoms.
In 240 preterm neonates with apnea, caffeine citrate was similarly effective to aminophylline overall, with caffeine showing a lower risk of tachycardia and lower mean heart rate.
Evening 200 mg caffeine worsened objective sleep: longer time to fall asleep, lower sleep efficiency and shorter total sleep time in both age groups.
Caffeine (200 mg) before sleep delayed sleep onset and reduced deep sleep, with stronger negative effects on daytime recovery sleep than nocturnal sleep.
A moderate caffeine dose (3 mg/kg) improved endurance cycling time similarly in women and men (~4–4.6% improvement).
Acute coffee and anhydrous caffeine before testing produced small improvements: coffee improved leg-press 1RM versus anhydrous caffeine, and caffeine attenuated reductions in sprint power/total work versus placebo.
Large randomized trial in very low birth-weight infants: caffeine reduced bronchopulmonary dysplasia (oxygen use at 36 weeks) and shortened positive airway pressure duration, with transiently reduced early weight gain and no increase in death or brain injury.
Acute caffeine (3 mg/kg) improved muscular velocity, power and endurance across sexes, with larger effects in lower-body (back squat) at moderate–high loads.
In preterm infants (<32 weeks), early prophylactic caffeine reduced duration of oxygen therapy and other respiratory support needs compared with therapeutic (delayed) caffeine.
Prophylactic acetaminophen + caffeine given before spinal anesthesia reduced frequency and severity of post-dural puncture headache and increased maternal satisfaction vs placebo.
Acute caffeine (3 mg/kg) alone improved muscular endurance, velocity and power (esp. back squat); co-ingestion with sodium bicarbonate did not produce additive benefit and attenuated caffeine's ergogenic effect.
Among undergraduates, 200 mg caffeine increased feelings of stimulation/high/anxiety and motivation; expecting a stronger stimulant (Adderall) amplified subjective stimulant effects and improved working memory, especially when combined with actual caffeine.
In 29 patients with panic disorder and 53 healthy controls (n=82), 150 mg caffeine did not increase subjective anxiety but did raise physiological arousal (SCR), increase costly avoidance behavior, and impair exteroceptive attention.
In preterm infants (n=78) comparing high-dose versus lower-dose caffeine citrate, there was no difference in frequency or days with apnoea; side-effect rates showed non-significant trends toward being higher with the higher dose.
In 27 male rugby players, 3 mg/kg caffeine (capsule, gum, or mouth rinse) produced limited effects: a small increase in countermovement-jump height and one-set squat endurance, but most strength/power measures were unchanged.
In 26 recreationally trained men, acute caffeine (6 mg/kg) increased countermovement jump height versus control and versus placebo; maximal power output was unchanged.
Acute caffeine (5 mg/kg) increased squat- and countermovement-jump heights and improved some force/velocity execution metrics in collegiate athletes.
IV or enteral caffeine given in delivery room was feasible; most infants had measurable caffeine blood levels but respiratory outcomes matched historical controls.
In older adults (42) and Parkinson's patients (24) who abstained from caffeine for a week, a single 100 mg caffeine dose improved response selection (accuracy) on choice reaction and Stroop tasks, sped Stroop RTs, improved dual-task (RSVP) performance via better T1 identification but impaired single-task RSVP performance; effects did not differ by disease.
In a cohort of infants of Latina mothers followed to 18–36 months (106 children with follow-up), days when children consumed caffeine were associated with higher calorie intake and lower intake of key nutrients; the educational intervention did not prevent overweight.
In 37 healthy adults undergoing total sleep deprivation with crossover acute caffeine/placebo, acute caffeine improved PVT reaction time, but higher habitual caffeine intake (>50 mg/day) was associated with worse vigilant attention (longer RT) and lower individual alpha frequency (IAF).
In 201 healthy volunteers, acute caffeine (200 mg added to decaf coffee) increased blood pressure and calculation speed overall; CYP1A2 genotype (rs762551 CC) showed larger systolic BP rise in low habitual consumers (≤90 mg/day).
A single caffeinated energy shot acutely raised systolic and diastolic blood pressure, but these elevations were not sustained after repeated daily use; ECG intervals were unchanged.
In 100 male undergraduates, both actual caffeine and the expectation of caffeine affected mood and performance; caffeine increased BP, pulse, and reduced fatigue.
Higher doses of caffeine (500 mg vs 100 mg) increased ambulatory systolic and diastolic blood pressure and heart rate during the workday.
Over 14 days, an ephedra‑caffeine weight‑loss product produced no significant changes in measured cardiovascular parameters versus placebo in healthy overweight adults.
In patients undergoing EPS, oral caffeine (5 mg/kg) increased systolic and diastolic blood pressure but did not affect cardiac conduction parameters or SVT inducibility.
Knowing about a possible placebo had limited effect overall; uninformed participants showed some caffeine-induced increases in diastolic blood pressure and vigor and impaired hand steadiness at higher dose.
In patients with familial LQTS, an energy drink containing caffeine acutely raised blood pressure and in some individuals caused large QTc prolongation.
Single 6 mg/kg caffeine increased blood pressure and tidal volume and raised plasma caffeine concentrations; epinephrine rose in able-bodied and paraplegic but not tetraplegic participants, with limited HRV changes.
In 110 men, acute caffeine raised systolic and diastolic blood pressure modestly (~+4 mmHg and +3 mmHg) and increased plasma adrenaline.
In overweight patients, a 6-week ephedrine (20 mg) plus caffeine (200 mg) treatment produced modest blood pressure reductions in some groups, heart-rate increase in normotensives, weight loss across groups, and frequent side-effects.
In 90 male adolescent athletes, acute caffeine (6 mg/kg) improved several performance measures (strength, jump height, sit-ups, and Yo-Yo endurance) versus placebo; these ergogenic effects were independent of ADORA2A and CYP1A2 genotypes.
Acute caffeine (6 mg/kg) increased repetitions to failure across sets, raised post-exercise blood lactate, and reduced perceived pain during low-load knee-extension with blood-flow restriction.
Caffeine increased time to exhaustion and oxygen deficit in a supramaximal anaerobic test and raised metabolic markers.
In 30 resistance-trained men, acute caffeine (6 mg/kg) increased blood lactate during resistance exercise, with greater lactate elevations in carriers of the MCT1 A allele (TA+AA) versus TT genotype; potassium responses varied by genotype and intervention.
In a crossover trial comparing guarana, caffeine (5 mg/kg) and placebo, caffeine showed no clear improvement in reaction time or memory versus placebo but did prevent post-exercise increases in simple reaction time variability.
In 29 healthy adults given sham low or high caffeine doses, belief/expectation did not change choice reaction time or 10 km running performance.
In healthy young adults, 75 mg caffeine reduced prefrontal oxygenated haemoglobin and increased deoxygenated haemoglobin and improved some reaction-time and mood measures; co‑administration with L‑theanine abolished the oxy‑Hb reduction and removed the behavioural benefits.
Among moderate habitual consumers, drinks containing caffeine became more pleasant over repeated exposures when caffeine intake was maintained, whereas pleasantness decreased in withdrawn participants.
Healthy young adults who regularly use caffeine got 200 mg caffeine plus varied CBD doses; self-reported drug effects and anxiety did not change.
Resistance-trained men completed multiple caffeine and placebo trials; caffeine often increased arousal and dynamic muscle-power measures but effects varied across repeated trials.
Active adults performed cycling in normoxia and simulated altitude after 6 mg/kg caffeine; caffeine did not improve exercise capacity but changed some physiological and perceptual responses during steady-state.
Two experiments showed 5 mg/kg caffeine increased knee-extensor strength and motor-unit recruitment and improved leg-cycling time-trial performance while reducing pain and perceived effort in some conditions.
Caffeine given immediately after birth to very preterm infants increased respiratory effort measures versus later administration.
In a double-blind crossover study of 23 mildly overweight adults, an acute multi-ingredient supplement containing high caffeine did not change heart rate or blood pressure but reduced RER in low-caffeine users.
Crossover trial in active young adults: 6 mg/kg caffeine acutely improved reaction time but did not change attention or memory and increased some side effects.
Double-blind crossover in active males given ~5 mg/kg/day caffeine for 4 days: caffeine did not change resting, total, or physical-activity energy expenditure or accelerometer-measured activity patterns.
Randomized, placebo-controlled trial in 80 men: acute pre-exercise 3 mg/kg caffeine improved 3-km running time and Wingate mean power output across groups; habitual caffeine use attenuated ergogenicity.
Phase III double-blind randomized trial in dental pain: ibuprofen 400 mg + caffeine 100 mg provided superior and faster analgesia versus ibuprofen alone, caffeine alone, and placebo over 8 h with acceptable tolerability.
In a large multicenter RCT, the acetaminophen+aspirin+caffeine combination provided faster and greater pain relief than ibuprofen and placebo in patients with severe migraine.
A single dose of a two-tablet analgesic containing acetaminophen, aspirin, and caffeine relieved migraine pain faster and more effectively than ibuprofen or placebo.
Randomized double-blind crossover in trained judoists: acute 6 and 9 mg/kg caffeine improved judo-specific performance (throws) and increased heart rate; habitual caffeine consumers were less responsive.
In young adults consuming combinations of beer and caffeine (various doses), alcohol decreased alertness and increased hedonic tone; high caffeine doses counteracted alcohol-related decreases in subjective alertness but did not reverse alcohol-induced performance impairments.
Caffeine increased blood pressure; expectancy/placebo effects influenced subjective alertness in one experiment, while reaction time showed no consistent change.
Placebo-caffeine study (participants believed they drank caffeinated water): social influence moderated responses—confirming confederate increased subjective alertness, reduced cognitive interference and raised product endorsement; disconfirming confederate produced larger SBP decreases.
In 27 healthy volunteers, 50 mg caffeine improved alertness and attention-switching accuracy; combined L-theanine (100 mg) plus caffeine improved speed and accuracy on attention-switching and reduced distraction in memory tasks.
A nutrient-enriched breakfast bar (containing a low caffeine dose of 21.5 mg among many other ingredients) produced acute improvements in alertness, attention and several cognitive tasks versus placebo on Day 1 and Day 56.
In young adults, a single dose of 97 mg L-theanine combined with 40 mg caffeine improved task-switching accuracy and increased self-reported alertness while reducing tiredness.
In 150 healthy adults, a drink with 40 mg caffeine + 60 g glucose improved overall multi-tasking performance and speed on some tasks versus placebo or glucose alone, without changing mood.
Among 162 caffeine-using smokers in cessation programs, continuing caffeine use after quitting raised plasma caffeine to ~203% of baseline by 3 weeks; abstainers reported transient increased fatigue and decreased stimulation but cessation rates were similar.
In elite jiu-jitsu athletes, 3 mg/kg caffeine increased throws in later SJFT sets, raised heart rate slightly, improved strength/endurance perception, and reduced fatigue perception, but did not change technical actions during real combat.
Caffeine increased time to exhaustion and oxygen deficit in a supramaximal anaerobic test and raised metabolic markers.
In elite male endurance athletes, 4.5 mg·kg-1 caffeine increased endurance performance and several physiological markers during incremental running to exhaustion.
A pre-workout drink containing BHB salts, ~100 mg caffeine and amino acids increased blood ketones and improved time-to-exhaustion by ~8–10% versus water.
Large case–control analysis found no clear evidence that maternal caffeine intake increases risk of cardiovascular birth defects.
In healthy active adults, single doses of thermogenic drinks with 100–140 mg caffeine increased resting metabolic rate; the 140 mg formula also increased resting fat oxidation, with no clear effects on exercise fat oxidation or VO2max.
Across three small experiments, caffeine reduced subjective drowsiness but produced mixed effects on subjective effort and no consistent performance improvements.
Acute caffeine (6 mg/kg) increased repetitions to failure across sets, raised post-exercise blood lactate, and reduced perceived pain during low-load knee-extension with blood-flow restriction.
In this pilot RCT, warm caffeinated coffee increased initial void volumes after catheter removal but did not change the proportion who spontaneously voided.
Caffeine in hot drinks produced dose-dependent autonomic/cardio responses (e.g., changes in heart rate, blood pressure and baroreflex measures) during ingestion.
Moderate caffeine users developed increased liking for a novel caffeinated flavour when tested in a caffeine-deprived state; liking extinguished if caffeine was removed or deprivation changed.
Acute caffeine raises blood pressure and five days of regular caffeine intake did not eliminate the BP response in about half of healthy adults.
Double-blind randomized placebo-controlled crossover in 52 taekwondo athletes (elite and sub-elite) showed that 3 mg/kg caffeine acutely improved agility and kicking performance and reduced session RPE, with effects varying by sex and competitive level.
In healthy young adults, a single 200 mg oral caffeine dose caused a significant decrease in choroidal thickness measured by OCT at 1 and 3 hours post-ingestion compared with placebo.
Controlled dosing over 11 days in healthy males showed no evidence that daily caffeine (up to 6 mg/kg/day) produced hypohydration or altered renal electrolyte measures compared with placebo.
In a large randomized study, 200 mg caffeine given after overnight sleep loss restored vigilant attention (PVT) deficits but generally did not improve higher‑order placekeeping performance for most participants.
Across two small crossover experiments, caffeinated beverages acutely stimulated autonomic measures (blood pressure, skin conductance), altered heart rate and skin temperature, and increased energetic arousal, with some dose‑dependent physiological effects.
Amounts of caffeine plus theobromine present in normal portions of chocolate improved energetic arousal and cognitive function versus placebo/white chocolate.
In older women with vascular disease/risks, higher usual caffeine intake (mainly caffeinated coffee) was associated with slower cognitive decline over ~5 years.
Intravenous caffeine produced dose-dependent effects on brain imaging: intermediate dose (2.5 mg/kg) maximized BOLD activation increase; highest dose (5 mg/kg) maximized cerebral blood flow response.
In 48 male volleyball players, 4-week supplementation plus resistance training showed that combined Rhodiola + caffeine improved jump power and reduced perceived exertion more than either supplement or placebo.
In 28 light caffeine consumers, caffeine altered some alcohol-related cognitive performance measures and increased subjective stimulation without reducing absolute perceived intoxication.
One cup of caffeinated espresso acutely raised blood pressure and heart rate but did not change QTc in healthy adults.
In a randomized trial of 95 patients with urinary symptoms, an education intervention reduced caffeine intake and produced significant improvements in urinary urgency and frequency at one month.
Regular coffee (450 mg/day) increased urinary urgency and frequency in young healthy volunteers, especially in prior low coffee users.
In a population survey and a controlled blinded experiment (57 regular users enrolled), abrupt caffeine withdrawal produced symptomatic withdrawal in a subset (e.g., headaches/tiredness), whereas gradual withdrawal produced minimal symptoms.
Participants given 200 mg caffeinated gum showed better sustained attention, reported being more on-task and had less mind-wandering versus placebo.
In 100 healthy drivers, a single 200 mg caffeine dose improved some executive/cognitive test performance and shortened brake reaction time versus placebo.
Plasma caffeine concentrations showed a small overall rise after CPAP treatment but did not differ between therapeutic and subtherapeutic CPAP groups.
In a large balanced placebo crossover, both caffeine (300 mg) and expectancy produced similar subjective effects (energy, reduced sleepiness); placebo altered caffeine pharmacokinetics.
In a randomized 14-day crossover trial, caffeinated coffee increased ventricular ectopy and daily steps and reduced nightly sleep duration versus avoiding caffeine, with no significant change in atrial ectopy.
In a randomized, double-blind, placebo-controlled trial, caffeine (2–4 mg/kg) improved 10-km cycling time overall but effects were strongly modified by CYP1A2 genotype (benefit in AA, harm in CC).
Acute coffee and anhydrous caffeine before testing produced small improvements: coffee improved leg-press 1RM versus anhydrous caffeine, and caffeine attenuated reductions in sprint power/total work versus placebo.
Large randomized trial in very low birth-weight infants: caffeine reduced bronchopulmonary dysplasia (oxygen use at 36 weeks) and shortened positive airway pressure duration, with transiently reduced early weight gain and no increase in death or brain injury.
In healthy aeromedically fit pilots, a single 300 mg dose of caffeine at midnight reduced the nighttime decline in psychomotor performance after extended wakefulness.
In young adults consuming combinations of beer and caffeine (various doses), alcohol decreased alertness and increased hedonic tone; high caffeine doses counteracted alcohol-related decreases in subjective alertness but did not reverse alcohol-induced performance impairments.
Caffeinated coffee increased alertness and psychomotor performance in people with colds (restoring them to healthy levels); decaffeinated coffee also produced improvements.
In PD outpatients, 100 mg/day caffeine adjuvant (2×50 mg/day) for 3 weeks was associated with substantial motor improvement (UPDRS III) compared to placebo, though some patients reported transient side effects.
Among undergraduates, 200 mg caffeine increased feelings of stimulation/high/anxiety and motivation; expecting a stronger stimulant (Adderall) amplified subjective stimulant effects and improved working memory, especially when combined with actual caffeine.
Acute 3 mg/kg caffeine improved peak and mean power in repeated Wingate sprints in both sexes with sex‑specific timing differences (males early sprints, females later sprints).
NaHCO3 and caffeine each improved some aspects of repeated-sprint performance, but their coingestion did not produce a synergistic benefit.
In 29 patients with panic disorder and 53 healthy controls (n=82), 150 mg caffeine did not increase subjective anxiety but did raise physiological arousal (SCR), increase costly avoidance behavior, and impair exteroceptive attention.
In preterm infants (n=78) comparing high-dose versus lower-dose caffeine citrate, there was no difference in frequency or days with apnoea; side-effect rates showed non-significant trends toward being higher with the higher dose.
In fasted young adults, combined caffeine (75 mg) + glucose (75 g) improved sustained attention and verbal memory consolidation beyond either substance alone; caffeine alone improved simple reaction time.
In older adults (42) and Parkinson's patients (24) who abstained from caffeine for a week, a single 100 mg caffeine dose improved response selection (accuracy) on choice reaction and Stroop tasks, sped Stroop RTs, improved dual-task (RSVP) performance via better T1 identification but impaired single-task RSVP performance; effects did not differ by disease.
In a cohort of infants of Latina mothers followed to 18–36 months (106 children with follow-up), days when children consumed caffeine were associated with higher calorie intake and lower intake of key nutrients; the educational intervention did not prevent overweight.
In 37 healthy adults undergoing total sleep deprivation with crossover acute caffeine/placebo, acute caffeine improved PVT reaction time, but higher habitual caffeine intake (>50 mg/day) was associated with worse vigilant attention (longer RT) and lower individual alpha frequency (IAF).
In 40 adults randomized to ~216 mg caffeine vs placebo, pattern‑reversal VEP P100 latency and amplitude measured at baseline and 1 h post‑dose were unchanged after caffeine.
In a crossover trial comparing guarana, caffeine (5 mg/kg) and placebo, caffeine showed no clear improvement in reaction time or memory versus placebo but did prevent post-exercise increases in simple reaction time variability.
Resistance-trained men completed multiple caffeine and placebo trials; caffeine often increased arousal and dynamic muscle-power measures but effects varied across repeated trials.
Active adults performed cycling in normoxia and simulated altitude after 6 mg/kg caffeine; caffeine did not improve exercise capacity but changed some physiological and perceptual responses during steady-state.
Two experiments showed 5 mg/kg caffeine increased knee-extensor strength and motor-unit recruitment and improved leg-cycling time-trial performance while reducing pain and perceived effort in some conditions.
Post-hoc analysis of a randomized crossover trial (placebo vs ~98 mg caffeine) showing that individual trait mental/physical energy and fatigue modify caffeine's effects on mood, cognitive (serial subtraction) and fine-motor (9‑hole peg) performance—people with higher trait fatigue often gained more benefit.
Randomized double-blind crossover in recreational males showed dose-dependent benefits of caffeine mouth rinse on selective attention: faster completion time with 300 mg, fewer errors with 150 mg, and reduced perceived difficulty at 150 and 300 mg vs placebo.
Randomized double-blind placebo-controlled parallel trial in surgeons/attendees (n=107) found no significant effect of caffeinated coffee (≈230 mg from 340 mL) vs decaffeinated coffee on laparoscopic simulator performance (fine motor dexterity).
Acute caffeine (50–450 mg) produced stimulant-like effects: increased blood pressure and arousal, improved vigilance, but worsened short-term memory in light nondependent users.
Caffeine increased blood pressure; expectancy/placebo effects influenced subjective alertness in one experiment, while reaction time showed no consistent change.
Caffeine increased self-rated alertness, jitteriness, and blood pressure in healthy adults; theanine opposed caffeine's blood pressure rise.
In 7- to 9-year-old children, moderate caffeine lowered heart rate and raised blood pressure during rest and low-moderate exercise but did not change VO2 or RER.
A single caffeinated coffee dose increased blood pressure and made participants more cooperative in a social game versus decaffeinated coffee.
In 22 resistance-trained men, acute caffeine (6 mg/kg) taken before resistance exercise raised blood-pressure-related measures compared with placebo and may increase cardiovascular load during/after heavy lifting.
In 49 moderate–high habitual consumers, a second 1.2 mg/kg caffeine dose improved cognitive performance and mood only after 8 h abstinence and raised blood pressure after 8 h; shorter abstinence produced some adverse effects on hand steadiness.
Daily caffeine 250 mg (alone or with DMAA) for 12 weeks produced no statistically significant adverse changes in measured clinical or laboratory outcomes.
In a double-blind crossover study of 23 mildly overweight adults, an acute multi-ingredient supplement containing high caffeine did not change heart rate or blood pressure but reduced RER in low-caffeine users.
Brief caffeine deprivation in habitual coffee drinkers caused decreased vigor, increased fatigue and sleepiness, and a modest drop in blood pressure; psychomotor performance unchanged.
Over 8 weeks, the caffeine arm showed no statistically significant changes in vital signs or routine lab safety measures compared with other groups.
In obese adults after weight loss, rye bread enriched with green tea extract (providing ~123–158 mg caffeine/day) did not improve weight-loss maintenance but was associated with slightly better blood pressure control and a marginally smaller waist circumference.
In 40 habitual coffee consumers in a randomized crossover design, single servings of coffee (160 mg caffeine) increased salivary alpha-amylase and transiently increased salivary gastrin and blood pressure, but did not change salivary cortisol or self-reported GI symptoms.
A bioactive combination including caffeine increased resting metabolic rate (thermogenesis) in men, and propranolol (beta-blocker) reduced about half of that thermogenic response.
Single 200 mg caffeine given overtly or covertly to healthy adults; large within-person variability in PK measures but no average covert vs overt difference.
Multiple-dose caffeine chewing gum produces dose-proportional plasma caffeine levels with maintained linear pharmacokinetics, supporting its use to sustain alertness.
Crossover trial in active young adults: 6 mg/kg caffeine acutely improved reaction time but did not change attention or memory and increased some side effects.
Double-blind crossover in active males given ~5 mg/kg/day caffeine for 4 days: caffeine did not change resting, total, or physical-activity energy expenditure or accelerometer-measured activity patterns.
A single cup of coffee (80 mg caffeine) produced a small rise in systolic BP but overall no statistically significant effect on BP at one hour in healthy young adults.
In tactical males, 300 mg caffeine and a 150 mg caffeine + methylliberine + theacrine combo similarly improved vigilance reaction time; caffeine raised DBP vs placebo while the combo raised SBP but not DBP.
In 165 healthy men and women across age/hormonal-status groups, acute caffeine increased systolic and diastolic blood pressure by a few mmHg.
Acute consumption of large-volume caffeinated energy drinks (two 16-oz bottles; ~304–320 mg caffeine) in healthy adults increased QTc and raised brachial and central blood pressure compared with placebo.
In undergraduates, 5 mg/kg caffeine increased systolic blood pressure and altered heart rate/HRV measures and subjective experience 40 minutes after ingestion; expectancies contributed to subjective effects but not objective measures.
Acute ingestion of various energy drinks (contain caffeine plus blends) produced group-specific increases in blood pressure, heart rate, cortisol, and mixed effects on anxiety and working memory.
Randomized, placebo-controlled trial in 80 men: acute pre-exercise 3 mg/kg caffeine improved 3-km running time and Wingate mean power output across groups; habitual caffeine use attenuated ergogenicity.
Phase III double-blind randomized trial in dental pain: ibuprofen 400 mg + caffeine 100 mg provided superior and faster analgesia versus ibuprofen alone, caffeine alone, and placebo over 8 h with acceptable tolerability.
Randomized double-blind crossover in trained judoists: acute 6 and 9 mg/kg caffeine improved judo-specific performance (throws) and increased heart rate; habitual caffeine consumers were less responsive.
In young adults consuming combinations of beer and caffeine (various doses), alcohol decreased alertness and increased hedonic tone; high caffeine doses counteracted alcohol-related decreases in subjective alertness but did not reverse alcohol-induced performance impairments.
In 150 healthy adults, a drink with 40 mg caffeine + 60 g glucose improved overall multi-tasking performance and speed on some tasks versus placebo or glucose alone, without changing mood.
Among 162 caffeine-using smokers in cessation programs, continuing caffeine use after quitting raised plasma caffeine to ~203% of baseline by 3 weeks; abstainers reported transient increased fatigue and decreased stimulation but cessation rates were similar.
Open-label decaf reduced withdrawal ratings in abstinent heavy coffee drinkers compared to water and to deceptively-treated decaf.
Ingesting coffee providing 3 mg/kg caffeine improved 5 km cycling time (~9 s faster, ≈1.9% vs placebo) in both men and women.
In elite jiu-jitsu athletes, 3 mg/kg caffeine increased throws in later SJFT sets, raised heart rate slightly, improved strength/endurance perception, and reduced fatigue perception, but did not change technical actions during real combat.
In a crossover RCT including people with or at risk for glaucoma, one cup of caffeinated coffee (182 mg) produced small but statistically significant increases in intraocular pressure (IOP), ocular perfusion pressure and ocular pulse amplitude at 60–90 min vs decaffeinated coffee.
Drinking caffeinated coffee raised eye pressure transiently in patients with glaucoma or ocular hypertension.
Caffeine plus heat exposure increased body and skin temperatures and amplified thermogenesis-related biomarkers (FGF‑21 and irisin).
Caffeine in hot drinks produced dose-dependent autonomic/cardio responses (e.g., changes in heart rate, blood pressure and baroreflex measures) during ingestion.
Moderate caffeine users developed increased liking for a novel caffeinated flavour when tested in a caffeine-deprived state; liking extinguished if caffeine was removed or deprivation changed.
Double-blind randomized placebo-controlled crossover in 52 taekwondo athletes (elite and sub-elite) showed that 3 mg/kg caffeine acutely improved agility and kicking performance and reduced session RPE, with effects varying by sex and competitive level.
In healthy young adults, a single 200 mg oral caffeine dose caused a significant decrease in choroidal thickness measured by OCT at 1 and 3 hours post-ingestion compared with placebo.
Controlled dosing over 11 days in healthy males showed no evidence that daily caffeine (up to 6 mg/kg/day) produced hypohydration or altered renal electrolyte measures compared with placebo.
In regular caffeine consumers tested when fatigued, repeated low doses of caffeine improved subjective mood/alertness and enhanced several performance measures, with dose‑dependent effects.
A 5 mg/kg dose of caffeine increased cycling time-to-exhaustion in both users and nonusers, with larger and longer-lasting effects in nonusers.
In older women with vascular disease/risks, higher usual caffeine intake (mainly caffeinated coffee) was associated with slower cognitive decline over ~5 years.
In trained women habituated to caffeine, acute caffeine (3 and 6 mg/kg) increased 1RM strength (dose-response) and 6 mg/kg increased time under tension; no clear change in repetitions or power measures.
In healthy older adults, a caffeinated coffee dose (~3 mg/kg) produced limited effects on balance metrics and did not change functional physical performance measures.
In rested young male habitual caffeine consumers, individualized morning caffeine doses reduced fatigue and improved simple and sustained attention and the executive updating domain, independent of meal ingestion.
In 58 adult females given 100 mg caffeine vs placebo after 24-h caffeine abstinence, no differences were found in acoustic or aerodynamic voice measures 30 minutes post-ingestion.
In a randomized trial of 95 patients with urinary symptoms, an education intervention reduced caffeine intake and produced significant improvements in urinary urgency and frequency at one month.
Regular coffee (450 mg/day) increased urinary urgency and frequency in young healthy volunteers, especially in prior low coffee users.
In a population survey and a controlled blinded experiment (57 regular users enrolled), abrupt caffeine withdrawal produced symptomatic withdrawal in a subset (e.g., headaches/tiredness), whereas gradual withdrawal produced minimal symptoms.
In 29 healthy adults given sham low or high caffeine doses, belief/expectation did not change choice reaction time or 10 km running performance.
Evening 200 mg caffeine worsened objective sleep: longer time to fall asleep, lower sleep efficiency and shorter total sleep time in both age groups.
Caffeinated coffee improved encoding of new information and reduced fatigue over the morning, but raised blood pressure and pulse; breakfast improved mood and some memory measures.
Realistic multi-dose caffeine intake (4×65 mg) and a single 200 mg dose both increased alertness and anxiety and improved several task-performance measures.
Repeated coffee mouth-rinses (dose-related) increased futsal-specific endurance distance and improved/accelerated recovery of vertical jump performance versus control.
Participants given 200 mg caffeinated gum showed better sustained attention, reported being more on-task and had less mind-wandering versus placebo.
In a crossover pilot trial with a caffeine active control, caffeine improved post-lunch rapid visual information processing and some multitasking measures versus placebo.
High-dose caffeine (8 mg/kg) increased maximal strength in bench press, deadlift, and squat and raised plasma Ca2+ compared with placebo or lower dose.
In smokers and nonsmokers, the urine metabolite ratio AAMU+1U+1X/17U from a spot urine correlated with measured caffeine clearance (CYP1A2 activity) across dosing conditions except at very high caffeine doses.
Caffeine citrate reduced apnea episodes and eliminated apnea faster than placebo in preterm infants and was well tolerated.
In 27 participants across three groups, slow-release caffeine reduced daytime sleepiness after an eastbound 7-time-zone flight but tended to affect sleep quality.
In sleep-restricted participants, a 200 mg caffeine capsule improved subjective mood and sped reaction times compared with placebo.
In moderately trained CrossFit athletes, different acute caffeine doses (3, 6, 9 mg/kg) did not produce consistent statistically superior performance vs placebo, though 6 mg/kg showed the largest practical improvement in some measures.
Multiple-dose caffeine chewing gum produces dose-proportional plasma caffeine levels with maintained linear pharmacokinetics, supporting its use to sustain alertness.
Multiple-dose caffeine chewing gum produces dose-proportional plasma caffeine levels with maintained linear pharmacokinetics, supporting its use to sustain alertness.
Caffeinated coffee increased alertness and psychomotor performance in people with colds (restoring them to healthy levels); decaffeinated coffee also produced improvements.
In this subgroup analysis of the CAP trial, caffeine reduced death/disability and shortened time on respiratory support mainly in infants who were receiving ventilatory support or who started caffeine early.
A single 100 mg caffeine dose produced rapid arousal (less sleepiness, greater activation) within 10–30 min in healthy undergraduates, with larger effects in men.
In resistance-trained women, 6 mg/kg caffeine improved leg-press muscular endurance (especially in fast CYP1A2 metabolizers) and affected subjective mood differently by genotype.
In 30 active young men, a moderate dose of caffeine over 4 days did not change total body water or its intracellular/extracellular compartments.
In 24 active participants, a caffeine mouth rinse during 40-min submaximal cycling likely improved certain aspects of cognitive control and time perception compared with placebo.
In acute STEMI patients, regular (caffeinated) coffee increased parasympathetic activity by up to 96% at 5 days without short-term adverse cardiac rhythm effects.
In healthy men, caffeine in gum was absorbed faster than capsules and delivered similar total amounts systemically at higher doses.
In young women, habitual preexercise caffeine supplementation (120 mg) prevented the exercise-training–induced reductions in exercising systolic blood pressure and double product seen in placebo group after 6 weeks.
In sleep-deprived healthy men, higher oral caffeine doses produced non-linear pharmacokinetics with slower metabolism.
In sleep-deprived trainees, 200–300 mg caffeine made sighting and trigger-pull faster without reducing shooting accuracy.
Salivary caffeine concentrations closely matched serum concentrations, so saliva can substitute for blood sampling in monitoring.
A 201 mg caffeine-containing supplement had no effect on 1-RM bench press strength or time to exhaustion at 85% VO2peak in these men.
Acute ingestion of black tea increased aortic stiffness briefly and both black and green tea raised wave reflections; effects were smaller than those produced by isolated caffeine.
Repeated day-long administration of tea or coffee sustained aspects of alertness and psychomotor performance but caused dose-dependent worsening of sleep onset, sleep time, and sleep quality.
Coffee (caffeinated and decaffeinated) increased arterial stiffness measures more in non-habitual than habitual drinkers; caffeine alone also raised stiffness measures in both groups.
Ingestion of an energy drink with 3 mg/kg caffeine increased perceived muscle power during exercise and raised the prevalence of side effects (e.g., insomnia).
Caffeine improved reaction time during administration and a conditioned context elicited similar improvement when placebo was given.
A normal dose of caffeinated coffee improved several executive function domains on the JEF and reduced Stroop reaction times compared to decaf.
Over 14 days, an ephedra‑caffeine weight‑loss product produced no significant changes in measured cardiovascular parameters versus placebo in healthy overweight adults.
Participants given 200 mg caffeinated gum showed better sustained attention, reported being more on-task and had less mind-wandering versus placebo.
In a large balanced placebo crossover, both caffeine (300 mg) and expectancy produced similar subjective effects (energy, reduced sleepiness); placebo altered caffeine pharmacokinetics.
High-dose caffeine (8 mg/kg) increased maximal strength in bench press, deadlift, and squat and raised plasma Ca2+ compared with placebo or lower dose.
In habitual caffeine-using young men, 200–400 mg caffeine combined with a mental stressor increased salivary alpha-amylase activity; placebo with stress did not.
Caffeinated coffee (3 mg/kg) improved 5-km cycling time (~8 seconds) and habitual caffeine intake level did not modify this ergogenic effect.
In healthy young women, caffeine alone improved working memory accuracy at ~T2 and combined tDCS+caffeine improved working memory accuracy (T1 and T2) and Stroop accuracy (T1) versus sham; caffeine alone did not improve inhibitory control and neither intervention affected cognitive flexibility.
200 mg caffeine reduced lower-alpha (alpha1, 8–10 Hz) power primarily in participants with higher habitual caffeine consumption; overall caffeine effects did not differ reliably across menstrual phases.
In 625 young women, habitual caffeine intake was not associated with bone mass overall, but among users of DMPA there was a modest reduction in bone mineral content.
Caffeine citrate reduced apnea episodes and eliminated apnea faster than placebo in preterm infants and was well tolerated.
In sleep-restricted participants, a 200 mg caffeine capsule improved subjective mood and sped reaction times compared with placebo.
In ambulatory surgical patients at risk for caffeine withdrawal, a 200 mg IV dose reduced postoperative headache incidence but did not shorten recovery time.
In 36 healthy adults, moderate acute caffeine (2.5 mg/kg doses) improved finger temperature and some perfusion measures during cold exposure and rewarming, especially after total sleep deprivation, but altered pain responses.
Double-blind study (12 caffeine, 12 placebo) found high acute caffeine intake increased renal calcium clearance markedly over 6 hours.
Adding 6 mg/kg caffeine before low-load BFR training did not increase maximal strength more than BFR alone but improved precision of force release and reduced motor unit discharge variability.
Chewing gum with 200 mg caffeine improved grip strength and some jumping and softball-specific performance measures in trained female players.
Randomized trial in preterm infants with apnea: caffeine citrate vs aminophylline (both with NCPAP) showed improved early pulmonary function, shorter oxygen/NCPAP support times, and fewer apnea events with caffeine citrate.
In formerly cocaine-dependent adults, cumulative caffeine increased feelings of jitteriness and anxiety more than in controls but did not produce cocaine-like effects or greater reinforcement.
In 25 healthy young men, a 50 mg caffeine drink reduced resting EEG alpha power and improved cognitive test performance (including working memory) about 30 minutes after ingestion.
In 30 active young men, a moderate dose of caffeine over 4 days did not change total body water or its intracellular/extracellular compartments.
In 13 younger and 13 older habitual moderate caffeine consumers, a single 3 mg/kg dose improved coincidence anticipation timing (reduced error) in both age groups.
In 21 active adults, 3 mg/kg caffeine increased Wingate mean and peak power versus placebo without affecting visual attention; CYP1A2 genotype did not alter these effects.
In trained male boxers, adding 3 mg/kg caffeine to a PAPE protocol increased the magnitude of Wingate performance gains and uniquely increased peak power and perceived power versus control.
In 127 young heavy episodic drinkers, alcohol impaired simulated driving and vigilance; adding caffeine to alcoholic beverage did not improve driving or attention performance.
In 24 active participants, a caffeine mouth rinse during 40-min submaximal cycling likely improved certain aspects of cognitive control and time perception compared with placebo.
In habitual caffeine consumers, only the highest acute dose (400 mg) improved vigilance and executive control of visual attention.
Five days of controlled caffeine intake produced few cognitive or psychomotor changes; only the Vigor-Activity mood subset increased in the 3 mg/kg/day group.
In 68 SEAL trainees after 72 h sleep deprivation and stress, 200–300 mg caffeine improved vigilance, reaction time, learning, and reduced fatigue/sleepiness vs placebo.
After drinking to intoxication, adding caffeine to beer improved perceived sleep quality and morning alertness but did not affect hangover or sleep duration.
In a VR stress task, caffeine increased salivary alpha-amylase after the task versus placebo; the task itself raised multiple stress markers.
Oral caffeine (3.3 mg/kg) at rest increased ACTH and cortisol in healthy young men.
An acute 5 mg/kg caffeine dose slightly improved a peripheral awareness (hand–eye) task but raised state anxiety; other low-intensity task performance was unchanged.
After a high caffeine dose, women not using oral contraceptives had much larger increases in urinary calcium and some other minerals than oral contraceptive users, suggesting OCs blunt caffeine's calciuric effect.
Participants given concurrent caffeinated and noncaffeinated cola showed limited but reliable self-administration in a subset (~25%) of individuals.
Salivary caffeine concentrations closely matched serum concentrations, so saliva can substitute for blood sampling in monitoring.
A 2 mg/kg dose of caffeine made people react faster, detect more targets, and encode new information faster compared with placebo/withdrawal.
A single 200 mg dose of caffeine enhanced left-hemisphere recognition of positive words compared with placebo.
In extremely premature infants, caffeine clearance and volume of distribution change with age and weight; caffeine is well absorbed and has prolonged elimination.
Acute multi-ingredient preworkout supplements (one formulation contained caffeine) modestly improved anaerobic power and some endurance and vascular measures versus placebo; caffeine was one of several active ingredients.
One cup of coffee (80 mg caffeine) taken during a break improved lane keeping and speed control and reduced subjective sleepiness for up to 2 hours.
In 8–10‑year‑old boys, a single dose of caffeine (5 mg/kg) increased mean (average) power on a Wingate test and raised peak heart rate, without affecting peak power or static hand-grip strength.
A liposome-encapsulated caffeine-based topical cream reduced subcutaneous fat thickness over 2 months compared with placebo.
A single dose of a multi-ingredient supplement containing 55 mg caffeine altered ECG intervals and autonomic (LF) measures in mentally fatigued adults.
In smokers and nonsmokers, the urine metabolite ratio AAMU+1U+1X/17U from a spot urine correlated with measured caffeine clearance (CYP1A2 activity) across dosing conditions except at very high caffeine doses.
In 42 trained cyclists, 6 mg/kg caffeine improved ~30‑min time‑trial performance versus placebo and control; correct identification of caffeine further increased the observed benefit.
In sleep-restricted participants, a 200 mg caffeine capsule improved subjective mood and sped reaction times compared with placebo.
In ambulatory surgical patients at risk for caffeine withdrawal, a 200 mg IV dose reduced postoperative headache incidence but did not shorten recovery time.
Double-blind study (12 caffeine, 12 placebo) found high acute caffeine intake increased renal calcium clearance markedly over 6 hours.
In 30 children (8–13 y), a single 80 mg oral caffeine dose increased physiological arousal (skin conductance) and altered EEG indices versus placebo.
Caffeine increases physiological arousal (higher skin conductance) and reduces EEG alpha; these effects add to those of opening the eyes.
Caffeine increased skin conductance (arousal) in children, but dose-response differed between AD/HD and control groups.
Adding 6 mg/kg caffeine before low-load BFR training did not increase maximal strength more than BFR alone but improved precision of force release and reduced motor unit discharge variability.
Caffeine substantially reduced cerebral blood flow and middle cerebral artery velocity, implying narrowing of cerebral arterioles and the MCA.
In 8–10‑year‑old boys, a single dose of caffeine (5 mg/kg) increased mean (average) power on a Wingate test and raised peak heart rate, without affecting peak power or static hand-grip strength.
Acute caffeine (5 mg/kg) increased peak anaerobic power and reduced perceived exertion for upper-body exercise in men.
Caffeine improved short-duration arm-crank power in paraplegic participants but showed no clear ergogenic effect in tetraplegic or able-bodied groups.
A single caffeinated energy shot acutely raised systolic and diastolic blood pressure, but these elevations were not sustained after repeated daily use; ECG intervals were unchanged.
In this subgroup analysis of the CAP trial, caffeine reduced death/disability and shortened time on respiratory support mainly in infants who were receiving ventilatory support or who started caffeine early.
Randomized trial in preterm infants with apnea: caffeine citrate vs aminophylline (both with NCPAP) showed improved early pulmonary function, shorter oxygen/NCPAP support times, and fewer apnea events with caffeine citrate.
A single 100 mg caffeine dose produced rapid arousal (less sleepiness, greater activation) within 10–30 min in healthy undergraduates, with larger effects in men.
In resistance-trained women, 6 mg/kg caffeine improved leg-press muscular endurance (especially in fast CYP1A2 metabolizers) and affected subjective mood differently by genotype.
In 25 healthy young men, a 50 mg caffeine drink reduced resting EEG alpha power and improved cognitive test performance (including working memory) about 30 minutes after ingestion.
In 30 active young men, a moderate dose of caffeine over 4 days did not change total body water or its intracellular/extracellular compartments.
In 21 active adults, 3 mg/kg caffeine increased Wingate mean and peak power versus placebo without affecting visual attention; CYP1A2 genotype did not alter these effects.
In 26 boys (8–10 y), 3 mg/kg caffeine increased peak power and both 3 and 5 mg/kg doses increased maximal grip strength; 5 mg/kg increased mean power and peak heart rate during Wingate.
In trained male boxers, adding 3 mg/kg caffeine to a PAPE protocol increased the magnitude of Wingate performance gains and uniquely increased peak power and perceived power versus control.
In 127 young heavy episodic drinkers, alcohol impaired simulated driving and vigilance; adding caffeine to alcoholic beverage did not improve driving or attention performance.
In 24 active participants, a caffeine mouth rinse during 40-min submaximal cycling likely improved certain aspects of cognitive control and time perception compared with placebo.
Caffeine given during extended wakefulness prevented the usual drop in alertness immediately after awakening (sleep inertia) in adults.
In acute STEMI patients, regular (caffeinated) coffee increased parasympathetic activity by up to 96% at 5 days without short-term adverse cardiac rhythm effects.
After drinking to intoxication, adding caffeine to beer improved perceived sleep quality and morning alertness but did not affect hangover or sleep duration.
In a VR stress task, caffeine increased salivary alpha-amylase after the task versus placebo; the task itself raised multiple stress markers.
In 40 habitual coffee consumers in a randomized crossover design, single servings of coffee (160 mg caffeine) increased salivary alpha-amylase and transiently increased salivary gastrin and blood pressure, but did not change salivary cortisol or self-reported GI symptoms.
A single caffeinated coffee dose increased blood pressure and made participants more cooperative in a social game versus decaffeinated coffee.
A single caffeinated coffee dose increased blood pressure and made participants more cooperative in a social game versus decaffeinated coffee.
In people with fibromyalgia, a 100 mg caffeinated chewing gum did not reduce exercise-induced muscle pain compared to placebo.
In young women, habitual preexercise caffeine supplementation (120 mg) prevented the exercise-training–induced reductions in exercising systolic blood pressure and double product seen in placebo group after 6 weeks.
In sleep-deprived healthy men, higher oral caffeine doses produced non-linear pharmacokinetics with slower metabolism.
Caffeine (200 mg) increased EEG arousal; a valerian/hop extract reduced or blocked that arousal at 60 minutes.
Salivary caffeine concentrations closely matched serum concentrations, so saliva can substitute for blood sampling in monitoring.
Repeated day-long administration of tea or coffee sustained aspects of alertness and psychomotor performance but caused dose-dependent worsening of sleep onset, sleep time, and sleep quality.
A 2 mg/kg dose of caffeine made people react faster, detect more targets, and encode new information faster compared with placebo/withdrawal.
Coffee (caffeinated and decaffeinated) increased arterial stiffness measures more in non-habitual than habitual drinkers; caffeine alone also raised stiffness measures in both groups.
A single 200 mg dose of caffeine enhanced left-hemisphere recognition of positive words compared with placebo.
Ingestion of an energy drink with 3 mg/kg caffeine increased perceived muscle power during exercise and raised the prevalence of side effects (e.g., insomnia).
In 90 male adolescent athletes, acute caffeine (6 mg/kg) improved several performance measures (strength, jump height, sit-ups, and Yo-Yo endurance) versus placebo; these ergogenic effects were independent of ADORA2A and CYP1A2 genotypes.
In extremely premature infants, caffeine clearance and volume of distribution change with age and weight; caffeine is well absorbed and has prolonged elimination.
A normal dose of caffeinated coffee improved several executive function domains on the JEF and reduced Stroop reaction times compared to decaf.
In 8–10‑year‑old boys, a single dose of caffeine (5 mg/kg) increased mean (average) power on a Wingate test and raised peak heart rate, without affecting peak power or static hand-grip strength.
A single dose of a multi-ingredient supplement containing 55 mg caffeine altered ECG intervals and autonomic (LF) measures in mentally fatigued adults.
In 625 young women, habitual caffeine intake was not associated with bone mass overall, but among users of DMPA there was a modest reduction in bone mineral content.
In 41 healthy volunteers, orally ingested caffeine (5 mg/kg) increased tear secretion measured by Schirmer 1 at 45 and 90 minutes after intake.
In 42 trained cyclists, 6 mg/kg caffeine improved ~30‑min time‑trial performance versus placebo and control; correct identification of caffeine further increased the observed benefit.
Caffeine citrate reduced apnea episodes and eliminated apnea faster than placebo in preterm infants and was well tolerated.
Acute caffeine (5 mg/kg) increased peak anaerobic power and reduced perceived exertion for upper-body exercise in men.
In 36 healthy adults, moderate acute caffeine (2.5 mg/kg doses) improved finger temperature and some perfusion measures during cold exposure and rewarming, especially after total sleep deprivation, but altered pain responses.
Double-blind study (12 caffeine, 12 placebo) found high acute caffeine intake increased renal calcium clearance markedly over 6 hours.
Bright light combined with 100 mg caffeine gum improved driving performance and subjective sleepiness more than caffeine alone in sleep-restricted young drivers.
Adding 6 mg/kg caffeine before low-load BFR training did not increase maximal strength more than BFR alone but improved precision of force release and reduced motor unit discharge variability.
Chewing gum with 200 mg caffeine improved grip strength and some jumping and softball-specific performance measures in trained female players.
Randomized double-blind placebo-controlled study: 200 mg caffeine given after learning reduced later face-recognition accuracy and increased false alarms compared with placebo.
Randomized trial in preterm infants with apnea: caffeine citrate vs aminophylline (both with NCPAP) showed improved early pulmonary function, shorter oxygen/NCPAP support times, and fewer apnea events with caffeine citrate.
In formerly cocaine-dependent adults, cumulative caffeine increased feelings of jitteriness and anxiety more than in controls but did not produce cocaine-like effects or greater reinforcement.
In 25 healthy young men, a 50 mg caffeine drink reduced resting EEG alpha power and improved cognitive test performance (including working memory) about 30 minutes after ingestion.
In 62 adults, pairing a caffeinated beverage with a novel yogurt increased liking and consumption of that yogurt, especially for low-energy-density yogurts.
In 21 active adults, 3 mg/kg caffeine increased Wingate mean and peak power versus placebo without affecting visual attention; CYP1A2 genotype did not alter these effects.
In habitual caffeine consumers, only the highest acute dose (400 mg) improved vigilance and executive control of visual attention.
In 100 male undergraduates, both actual caffeine and the expectation of caffeine affected mood and performance; caffeine increased BP, pulse, and reduced fatigue.
Five days of controlled caffeine intake produced few cognitive or psychomotor changes; only the Vigor-Activity mood subset increased in the 3 mg/kg/day group.
In 68 SEAL trainees after 72 h sleep deprivation and stress, 200–300 mg caffeine improved vigilance, reaction time, learning, and reduced fatigue/sleepiness vs placebo.
In healthy men, caffeine in gum was absorbed faster than capsules and delivered similar total amounts systemically at higher doses.
After drinking to intoxication, adding caffeine to beer improved perceived sleep quality and morning alertness but did not affect hangover or sleep duration.
In a VR stress task, caffeine increased salivary alpha-amylase after the task versus placebo; the task itself raised multiple stress markers.
In undergraduates, 5 mg/kg caffeine increased systolic blood pressure and altered heart rate/HRV measures and subjective experience 40 minutes after ingestion; expectancies contributed to subjective effects but not objective measures.
Acute ingestion of various energy drinks (contain caffeine plus blends) produced group-specific increases in blood pressure, heart rate, cortisol, and mixed effects on anxiety and working memory.
Oral caffeine (3.3 mg/kg) at rest increased ACTH and cortisol in healthy young men.
In healthy adults undergoing prolonged wakefulness, acute caffeine altered IGF-1 responses depending on COMT genotype and reduced the drop in testosterone during sleep deprivation.
Short-term HRV increased after drinking caffeinated espresso, decaf, or water; no clear specific short-term vagal effect of caffeine overall, though non-habitual consumers showed systolic BP increases.
An acute 5 mg/kg caffeine dose slightly improved a peripheral awareness (hand–eye) task but raised state anxiety; other low-intensity task performance was unchanged.
In healthy young men, 300 mg caffeine before moderate exercise delayed vagal (parasympathetic) heart-rate recovery after exercise in men with lower cardiorespiratory fitness.
After a high caffeine dose, women not using oral contraceptives had much larger increases in urinary calcium and some other minerals than oral contraceptive users, suggesting OCs blunt caffeine's calciuric effect.
Participants given concurrent caffeinated and noncaffeinated cola showed limited but reliable self-administration in a subset (~25%) of individuals.
Moderate caffeine (100–200 mg) did not change heart rate variability in young habitual male users within 90 minutes.
In people with and without long-standing type 1 diabetes, two weeks of moderate caffeine increased heart rate variability (a marker of autonomic function).
Managers deprived of their usual caffeine showed withdrawal discomfort and decreased performance on several complex task measures.
Managers deprived of their usual caffeine showed withdrawal discomfort and decreased performance on several complex task measures.
In extremely premature infants, caffeine clearance and volume of distribution change with age and weight; caffeine is well absorbed and has prolonged elimination.
Habitual postlunch caffeine users developed increased preference for a flavor paired with caffeine and had improved postlunch mood.
One cup of coffee (80 mg caffeine) taken during a break improved lane keeping and speed control and reduced subjective sleepiness for up to 2 hours.
In a within‑subjects study of healthy men, adding caffeine or energy drink to alcohol did not reduce subjective intoxication (no reproducible 'masking effect') and did not alter breath alcohol concentrations.
In 36 healthy adults, moderate acute caffeine (2.5 mg/kg doses) improved finger temperature and some perfusion measures during cold exposure and rewarming, especially after total sleep deprivation, but altered pain responses.
Repeated nighttime caffeine gum improved objective performance during 50 h wakefulness but did not change overall self-reported sleepiness or fatigue.
Repeated nighttime caffeine gum improved objective performance during 50 h wakefulness but did not change overall self-reported sleepiness or fatigue.
In healthy young males, 200 mg caffeine improved sustained attention (shorter reaction time) but showed no robust effects on most other cognitive domains or subjective fatigue.
Two-week daily matcha (contains caffeine) preserved attention after mild stress in young adults.
Chewing gum with 200 mg caffeine improved grip strength and some jumping and softball-specific performance measures in trained female players.
In this subgroup analysis of the CAP trial, caffeine reduced death/disability and shortened time on respiratory support mainly in infants who were receiving ventilatory support or who started caffeine early.
Randomized double-blind placebo-controlled study: 200 mg caffeine given after learning reduced later face-recognition accuracy and increased false alarms compared with placebo.
A single 100 mg caffeine dose produced rapid arousal (less sleepiness, greater activation) within 10–30 min in healthy undergraduates, with larger effects in men.
In resistance-trained women, 6 mg/kg caffeine improved leg-press muscular endurance (especially in fast CYP1A2 metabolizers) and affected subjective mood differently by genotype.
In formerly cocaine-dependent adults, cumulative caffeine increased feelings of jitteriness and anxiety more than in controls but did not produce cocaine-like effects or greater reinforcement.
In 62 adults, pairing a caffeinated beverage with a novel yogurt increased liking and consumption of that yogurt, especially for low-energy-density yogurts.
In 7- to 9-year-old children, moderate caffeine lowered heart rate and raised blood pressure during rest and low-moderate exercise but did not change VO2 or RER.
Five days of controlled caffeine intake produced few cognitive or psychomotor changes; only the Vigor-Activity mood subset increased in the 3 mg/kg/day group.
In healthy men, caffeine in gum was absorbed faster than capsules and delivered similar total amounts systemically at higher doses.
Short-term HRV increased after drinking caffeinated espresso, decaf, or water; no clear specific short-term vagal effect of caffeine overall, though non-habitual consumers showed systolic BP increases.
An acute 5 mg/kg caffeine dose slightly improved a peripheral awareness (hand–eye) task but raised state anxiety; other low-intensity task performance was unchanged.
In healthy young men, 300 mg caffeine before moderate exercise delayed vagal (parasympathetic) heart-rate recovery after exercise in men with lower cardiorespiratory fitness.
After a high caffeine dose, women not using oral contraceptives had much larger increases in urinary calcium and some other minerals than oral contraceptive users, suggesting OCs blunt caffeine's calciuric effect.
In sleep-deprived healthy men, higher oral caffeine doses produced non-linear pharmacokinetics with slower metabolism.
In healthy children, low–moderate caffeine doses raised preexercise blood pressure and lowered heart rate by ~5–6 bpm; metabolic measures were largely unchanged.
In healthy children, low–moderate caffeine doses raised preexercise blood pressure and lowered heart rate by ~5–6 bpm; metabolic measures were largely unchanged.
Participants given concurrent caffeinated and noncaffeinated cola showed limited but reliable self-administration in a subset (~25%) of individuals.
In sleep-deprived trainees, 200–300 mg caffeine made sighting and trigger-pull faster without reducing shooting accuracy.
A 201 mg caffeine-containing supplement had no effect on 1-RM bench press strength or time to exhaustion at 85% VO2peak in these men.
Repeated day-long administration of tea or coffee sustained aspects of alertness and psychomotor performance but caused dose-dependent worsening of sleep onset, sleep time, and sleep quality.
Coffee (caffeinated and decaffeinated) increased arterial stiffness measures more in non-habitual than habitual drinkers; caffeine alone also raised stiffness measures in both groups.
Acute caffeine (6 mg/kg) increased repetitions to failure across sets, raised post-exercise blood lactate, and reduced perceived pain during low-load knee-extension with blood-flow restriction.
Habitual postlunch caffeine users developed increased preference for a flavor paired with caffeine and had improved postlunch mood.
One cup of coffee (80 mg caffeine) taken during a break improved lane keeping and speed control and reduced subjective sleepiness for up to 2 hours.
In a within‑subjects study of healthy men, adding caffeine or energy drink to alcohol did not reduce subjective intoxication (no reproducible 'masking effect') and did not alter breath alcohol concentrations.
One cup of caffeinated espresso acutely raised blood pressure and heart rate but did not change QTc in healthy adults.
A single dose of a multi-ingredient supplement containing 55 mg caffeine altered ECG intervals and autonomic (LF) measures in mentally fatigued adults.
In patients with familial LQTS, an energy drink containing caffeine acutely raised blood pressure and in some individuals caused large QTc prolongation.
Experienced gamers who took a microalgae extract combined with guarana (natural caffeine) showed some improvements in reaction time and certain cognitive tests after acute and 30-day supplementation, while gaming scores did not significantly change.
Experienced gamers who took a microalgae extract combined with guarana (natural caffeine) showed some improvements in reaction time and certain cognitive tests after acute and 30-day supplementation, while gaming scores did not significantly change.
Experienced gamers who took a microalgae extract combined with guarana (natural caffeine) showed some improvements in reaction time and certain cognitive tests after acute and 30-day supplementation, while gaming scores did not significantly change.
In 24 healthy volunteers undergoing 32-hour sleep deprivation, single doses of slow-release caffeine (notably 300 mg) improved vigilance and performance for up to 13 hours compared with placebo.
In 24 healthy volunteers undergoing 32-hour sleep deprivation, single doses of slow-release caffeine (notably 300 mg) improved vigilance and performance for up to 13 hours compared with placebo.
A single high dose of caffeine (9 mg/kg) shortened muscle contraction time and reduced maximal displacement in professional handball players.
A single high dose of caffeine (9 mg/kg) shortened muscle contraction time and reduced maximal displacement in professional handball players.
A caffeine-based multi-ingredient supplement improved reactive agility (~3.4% faster) but did not significantly change jump height in recreational male handball players.
A caffeine-based multi-ingredient supplement improved reactive agility (~3.4% faster) but did not significantly change jump height in recreational male handball players.
Caffeine (200 mg) before sleep delayed sleep onset and reduced deep sleep, with stronger negative effects on daytime recovery sleep than nocturnal sleep.
Intravenous caffeine (4 mg/kg) abolished ischemic preconditioning protection in humans and eliminated the protective recovery seen in isolated human atrial tissue.
Intravenous caffeine (4 mg/kg) abolished ischemic preconditioning protection in humans and eliminated the protective recovery seen in isolated human atrial tissue.
In sleep-deprived adults, 2.5 mg/kg caffeine reduced PVT lapses and increased reaction speed at several timepoints; genetic polymorphisms modulated the magnitude/timing of effects.
In sleep-deprived adults, 2.5 mg/kg caffeine reduced PVT lapses and increased reaction speed at several timepoints; genetic polymorphisms modulated the magnitude/timing of effects.
In sleep-deprived adults, 2.5 mg/kg caffeine reduced PVT lapses and increased reaction speed at several timepoints; genetic polymorphisms modulated the magnitude/timing of effects.
Caffeine ingestion and mouth rinse produced small improvements in 3-km cycling performance; benefits varied by CYP1A2 genotype and were greater in early-day trials.
Caffeine ingestion and mouth rinse produced small improvements in 3-km cycling performance; benefits varied by CYP1A2 genotype and were greater in early-day trials.
Caffeine ingestion and mouth rinse produced small improvements in 3-km cycling performance; benefits varied by CYP1A2 genotype and were greater in early-day trials.
In 43 men, 3 mg/kg caffeine acutely did not change plantarflexor peak torque or rate of torque development.
In 43 men, 3 mg/kg caffeine acutely did not change plantarflexor peak torque or rate of torque development.
In 26 boys (8–10 y), 3 mg/kg caffeine increased peak power and both 3 and 5 mg/kg doses increased maximal grip strength; 5 mg/kg increased mean power and peak heart rate during Wingate.
In 26 boys (8–10 y), 3 mg/kg caffeine increased peak power and both 3 and 5 mg/kg doses increased maximal grip strength; 5 mg/kg increased mean power and peak heart rate during Wingate.
In 120 healthy adults, a single 200 mg caffeine dose acutely decreased macular (superficial and deep) and radial peripapillary vessel densities and reduced FD-300, without changing FAZ area/perimeter or IOP/BP.
In 120 healthy adults, a single 200 mg caffeine dose acutely decreased macular (superficial and deep) and radial peripapillary vessel densities and reduced FD-300, without changing FAZ area/perimeter or IOP/BP.
In 120 healthy adults, a single 200 mg caffeine dose acutely decreased macular (superficial and deep) and radial peripapillary vessel densities and reduced FD-300, without changing FAZ area/perimeter or IOP/BP.
In 128 preterm infants randomized to prophylactic caffeine citrate or control, early caffeine was associated with higher overall effectiveness, fewer apneas, shorter ventilation and hospitalization, lower inflammatory markers, better growth and neurodevelopment scores, and reduced BPD incidence.
In 128 preterm infants randomized to prophylactic caffeine citrate or control, early caffeine was associated with higher overall effectiveness, fewer apneas, shorter ventilation and hospitalization, lower inflammatory markers, better growth and neurodevelopment scores, and reduced BPD incidence.
In 128 preterm infants randomized to prophylactic caffeine citrate or control, early caffeine was associated with higher overall effectiveness, fewer apneas, shorter ventilation and hospitalization, lower inflammatory markers, better growth and neurodevelopment scores, and reduced BPD incidence.
A single 200 mg dose of caffeine given immediately after practice did not improve 24-hour retention of a visuomotor tracking skill compared with placebo.
A single 200 mg dose of caffeine given immediately after practice did not improve 24-hour retention of a visuomotor tracking skill compared with placebo.
A single 200 mg dose of caffeine given immediately after practice did not improve 24-hour retention of a visuomotor tracking skill compared with placebo.
A 3 mg/kg caffeine dose produced a small (6–8%) nonsignificant global perfusion decrease and selective regional activations (inferior frontal gyrus/anterior insula, hypothalamus) but no activation of nucleus accumbens.
A 3 mg/kg caffeine dose produced a small (6–8%) nonsignificant global perfusion decrease and selective regional activations (inferior frontal gyrus/anterior insula, hypothalamus) but no activation of nucleus accumbens.
A 3 mg/kg caffeine dose produced a small (6–8%) nonsignificant global perfusion decrease and selective regional activations (inferior frontal gyrus/anterior insula, hypothalamus) but no activation of nucleus accumbens.
In 210 men with androgenetic alopecia, topical 0.2% caffeine for 6 months increased anagen hair ratio (~+10.6%) and was noninferior to 5% minoxidil (~+11.7%).
In 22 resistance-trained men, acute caffeine (6 mg/kg) taken before resistance exercise raised blood-pressure-related measures compared with placebo and may increase cardiovascular load during/after heavy lifting.
In a crossover trial, 300 mg caffeine given before resistance exercise delayed autonomic (HRV) recovery and slowed heart rate and blood pressure recovery after exercise.
In 21 healthy young men given bedtime caffeine (160 mg delayed-release), higher plasma caffeine reduced NREM EEG delta power, lowered heart rate (~−3.24 bpm average) and increased high-frequency HRV during sleep.
In 21 healthy young men given bedtime caffeine (160 mg delayed-release), higher plasma caffeine reduced NREM EEG delta power, lowered heart rate (~−3.24 bpm average) and increased high-frequency HRV during sleep.
In 21 healthy young men given bedtime caffeine (160 mg delayed-release), higher plasma caffeine reduced NREM EEG delta power, lowered heart rate (~−3.24 bpm average) and increased high-frequency HRV during sleep.
Daily 120–150 mg caffeine for 2 weeks reduced burning mouth syndrome symptoms (VAS) versus control; 65.1% of caffeine-treated patients reported symptom relief versus 12.5% in controls.
Daily 120–150 mg caffeine for 2 weeks reduced burning mouth syndrome symptoms (VAS) versus control; 65.1% of caffeine-treated patients reported symptom relief versus 12.5% in controls.
A single 250 mg dose of caffeine before donation reduced vasovagal reaction scores, required fewer interventions, and increased reported likelihood of repeat donation in first-time female donors.
A single 250 mg dose of caffeine before donation reduced vasovagal reaction scores, required fewer interventions, and increased reported likelihood of repeat donation in first-time female donors.
A single 250 mg dose of caffeine before donation reduced vasovagal reaction scores, required fewer interventions, and increased reported likelihood of repeat donation in first-time female donors.
Acute caffeine doses strongly increased salivary cortisol after abstinence; after 5 days of daily caffeine (300 or 600 mg/day) the morning cortisol response to a 9:00 AM caffeine challenge was blunted, indicating partial tolerance, with some cortisol elevation returning after later doses.
Randomized trial in 78 very low birth weight preterm infants: higher maintenance caffeine citrate dose (10 mg/kg) improved apnea response rate versus lower dose (5 mg/kg) without increasing adverse events or mortality.
Randomized trial in 78 very low birth weight preterm infants: higher maintenance caffeine citrate dose (10 mg/kg) improved apnea response rate versus lower dose (5 mg/kg) without increasing adverse events or mortality.
Randomized crossover in 50 surgical trainees: acute 200 mg caffeine did not change laparoscopic task times or OSATS scores overall, but one error (tissue dislocation in circle cutting) was more frequent after caffeine; systolic BP rose slightly and more participants felt uncomfortable after caffeine.
Randomized crossover in 50 surgical trainees: acute 200 mg caffeine did not change laparoscopic task times or OSATS scores overall, but one error (tissue dislocation in circle cutting) was more frequent after caffeine; systolic BP rose slightly and more participants felt uncomfortable after caffeine.
Randomized crossover in 50 surgical trainees: acute 200 mg caffeine did not change laparoscopic task times or OSATS scores overall, but one error (tissue dislocation in circle cutting) was more frequent after caffeine; systolic BP rose slightly and more participants felt uncomfortable after caffeine.
Large PET imaging series (6087 scans) showed that even low serum caffeine reduces quantitative myocardial stress perfusion and coronary flow reserve during vasodilator stress, and in a small fraction alters coronary flow capacity interpretation (possible false negatives/positives).
In children who habitually consume caffeine, a 50 mg dose after overnight abstinence restored cognitive accuracy, prevented withdrawal headache, and increased alertness; non/low-consumers showed no clear benefit.
In endurance-trained adults, 3 mg/kg caffeine increased mean power in a 6-min time trial (~+12 W) but did not add to creatine effects on 15-s sprint power.
Higher caffeinated coffee/caffeine intake was associated with higher plasma SHBG and lower type 2 diabetes risk; adjustment for SHBG attenuated the diabetes association.
In 240 preterm neonates with apnea, caffeine citrate was similarly effective to aminophylline overall, with caffeine showing a lower risk of tachycardia and lower mean heart rate.
Large randomized double-blind trial showing that adding caffeine to ibuprofen improved relief of tension-type headache vs components or placebo.
Adolescents exposed to a novel soda with 2 mg/kg caffeine showed increased liking over repeated exposures and reduced bitterness perception.
Experimental induction of caffeine craving impaired memory performance and some metacognitive judgments compared to control.
In 24 habitual caffeine consumers and 24 non-consumers, acute caffeine (75 or 150 mg) improved reaction times, vigilance and working memory and reduced self-rated mental fatigue and increased alertness regardless of habitual use.
In middle-aged adults, 2-week intake of a tea catechin beverage (containing ~88 mg caffeine) increased energy expenditure after ingestion by ~96 kJ/day (~1.7%) versus a caffeinated placebo beverage; fasting RMR did not change.
Both domestic and imported caffeine citrate were similarly safe and effective for treating apnea in preterm infants.
300 mg caffeine worsened motor steadiness (more errors) in healthy adult females.
Caffeine has a long half-life in preterm infants and many infants had pathologic apnea days after stopping caffeine.
A single cup-equivalent dose after overnight abstinence increased energetic mood and improved psychomotor performance; additional spaced doses added little.
Caffeine improved neonatal respiratory compliance and reduced oxygen needs earlier than theophylline.
Combined caffeine and glucose did not change behavioral sustained attention but reduced activation in attention-related brain regions, suggesting increased neural efficiency.
In healthy young adults, 75 mg caffeine reduced prefrontal oxygenated haemoglobin and increased deoxygenated haemoglobin and improved some reaction-time and mood measures; co‑administration with L‑theanine abolished the oxy‑Hb reduction and removed the behavioural benefits.
In patients undergoing EPS, oral caffeine (5 mg/kg) increased systolic and diastolic blood pressure but did not affect cardiac conduction parameters or SVT inducibility.
In very preterm infants randomized to early high- vs standard-dose caffeine, high-dose was associated with higher rates of cerebellar hemorrhage and subtle neonatal neurobehavioral differences but no detectable 2-year developmental differences in this pilot trial.
About 3 mg/kg caffeine increased parasympathetic reactivation after submaximal exercise (60–300 s post-exercise) but did not alter resting cardiac parasympathetic modulation or HRV threshold.
In obese adolescents on a calorie-restricted diet, an ephedrine+caffeine pill produced much larger weight, BMI, and body-fat loss over 20 weeks than placebo.
A 6-month randomized trial of an herbal ephedra/caffeine product produced greater weight loss than placebo and increased some GI and sleep-related side effects.
Combination treatment including ephedrine plus caffeine reduced body fat and altered lipid-related gene expression; caffeine was given as part of a multi-drug regimen so individual caffeine effects are not isolated.
Survey of 4,271 US college students found that mixing energy drinks with alcohol was common and associated with higher heavy drinking and more alcohol-related harms.
In a double-blind crossover study, moderate caffeine during 38 h wakefulness reduced recovery-night total sleep time and N3 sleep and worsened sleep continuity and EEG slow-wave power.
In 84 patients, coadministration of ibuprofen plus caffeine did not reduce the risk or intensity of bleaching-induced tooth sensitivity compared with placebo.
In 58 adults, 12 weeks of catechin- and caffeine-containing green tea supplementation did not change gut microbiota composition or diversity nor body composition versus placebo.
In 20 mild hypertensive and 12 normotensive men (total 32), caffeine increased blood pressure and rate-pressure product at rest and during exercise, raising cardiac workload in hypertensives.
Knowing about a possible placebo had limited effect overall; uninformed participants showed some caffeine-induced increases in diastolic blood pressure and vigor and impaired hand steadiness at higher dose.
During an 18-km run, sports drinks increased gastrointestinal complaint incidence versus water; adding caffeine (150 mg/L) to the sports drink did not affect running performance or GI complaints compared with the sports drink without caffeine.
Daily caffeine challenges produced small but persistent increases in ambulatory blood pressure in some habitual consumers after repeated intake.
Daily use of a shampoo containing caffeine plus DMG‑Na reduced hair shedding and improved hair growth measures versus placebo after 6 months.
In very preterm infants randomized to higher vs lower caffeine citrate dosing, there was a borderline higher mean cognitive score at 1 year in the high-dose group but no clear adverse developmental, temperament, or behavior effects.
In overweight adults, 8 weeks of caffeinated coffee increased adiponectin and IL‑6 while decaffeinated coffee lowered fetuin‑A; no change in glucose tolerance.
Neonatal caffeine therapy was not associated with differences in sleep duration or sleep-disordered breathing at school age.
Adding caffeine to ibuprofen sped pain relief onset and increased analgesic effect at 45–60 minutes after single-dose administration, with few adverse events.
In 101 children/adolescents, caffeine produced larger cardiovascular responses in boys than girls after puberty and responses varied across the menstrual cycle in postpubertal girls.
A 480 mg oral caffeine challenge induced panic attacks in a higher proportion of patients with panic disorder and depression with panic attacks than in depressed-only patients or healthy controls.
Night-shift simulation: caffeine (2 mg/kg at two nighttime points) reduced physiological sleep tendency at night but did not change task performance or daytime sleep measures.
A combined caffeine+ephedra supplement raised resting metabolic rate and produced greater weight and fat loss than placebo over 12 weeks.
In a double-blind trial, 300 mg caffeine caused people to generate fewer options but to start generating options faster; caffeine did not affect subsequent choice selection.
Topical 2% caffeine alone did not slow myopia progression over 12 months; atropine (0.02%) slowed progression and caffeine did not alter atropine's efficacy when combined.
In moderately trained CrossFit athletes, different acute caffeine doses (3, 6, 9 mg/kg) did not produce consistent statistically superior performance vs placebo, though 6 mg/kg showed the largest practical improvement in some measures.
In infants with bronchiolitis-associated apnea, a single IV caffeine dose did not shorten time to a 24-hour apnea-free period compared with placebo.
Acute caffeine (5 mg/kg) increased peak anaerobic power and reduced perceived exertion for upper-body exercise in men.
IV caffeine after spinal anesthesia reduced headache severity, fewer moderate/severe headaches, and reduced analgesic needs.
Adding caffeine to paracetamol sped absorption (shorter Tmax), increased Cmax and Ka, and prolonged t1/2—effects greater in hepatic patients.
Early prophylactic caffeine in very preterm infants improved white-matter microstructure on MRI and reduced apnea/ventilation needs versus placebo.
Caffeine combined with work stress produced additive increases in blood pressure in medical students, especially those at high familial risk for hypertension.
Over six pairings, drinks paired with 19 mg caffeine + 250 mg theobromine became liked more than placebo‑paired drinks, suggesting methylxanthines increase acquired liking.
In 36 volunteers, drinking unfiltered natural coffee for 4 weeks raised plasma homocysteine, whereas modified (filtered/treated) coffee tended to lower it; other vitamins not notably reported.
In a double-blind crossover trial, caffeine taken before a mental stressor amplified cardiovascular/hemodynamic stress responses in both men and women.
In adults with tinnitus, a single 300 mg caffeine dose did not produce clinically meaningful changes in tinnitus-related discomfort or psychoacoustic measures compared to placebo.
In 28 participants (14 habituated, 14 non-habituated), 5 mg/kg caffeine increased end-exercise esophageal temperature and attenuated skin blood flow responses in caffeine-habituated individuals but had no effect in non-habituated participants or on sweating.
Perioperative substitution of patients' usual caffeine intake prevented postoperative headaches compared with placebo in habitual consumers.
In 51 patients with systolic heart failure, acute high-dose caffeine (total 500 mg) did not increase ventricular or supraventricular premature beats or exercise-derived arrhythmias compared with placebo.
In 27 healthy volunteers, 50 mg caffeine improved alertness and attention-switching accuracy; combined L-theanine (100 mg) plus caffeine improved speed and accuracy on attention-switching and reduced distraction in memory tasks.
In adults 50–69, single-dose caffeine shortened reaction times on several cognitive tasks and 12-week caffeine or matcha intake preserved MMSE-J scores versus placebo; matcha additionally improved work on a stress task with continuous intake.
A mixed herbal preparation containing Yerba Maté and Guarana (sources of caffeine) delayed gastric emptying and produced greater short-term weight loss versus placebo over 45 days.
Daily ingestion of a caffeine-containing supplement (≈201 mg/day) during 8 weeks of aerobic training produced no additional improvements in VO2peak, time to exhaustion, or body composition versus placebo.
Two randomized crossover trials in men showed beverages containing green tea catechins and coffee chlorogenic acids (with matched caffeine) raised postprandial GLP-1, lowered GIP, and reduced post-meal blood glucose compared to placebo.
Acute ingestion of green or black tea produced larger short-term increases in clinic systolic and diastolic blood pressure than caffeine-matched water, but regular 7-day tea consumption did not significantly change 24-h ambulatory blood pressure.
Sleep restriction (5 h) impaired tennis serving accuracy; a single 80 mg caffeine dose did not restore accuracy in semi-professional players.
Higher maintenance caffeine citrate dose (10 mg/kg/day vs 5 mg/kg/day) reduced extubation failure, apnea days and shortened time to extubation in very preterm infants.
In healthy adults, caffeinated coffee acutely delayed insulin rise and increased postprandial glucose exposure compared with water; effects varied by sex and BMI.
Early caffeine did not shorten time to first successful extubation in ventilated preterm infants and showed a non-significant trend toward higher mortality in the caffeine group.
Randomized comparison of caffeine versus aminophylline for apnea of prematurity showed trends toward lower risks of cognitive, motor, and language impairments with caffeine but differences were not statistically significant.
In 165 healthy men and women across age/hormonal-status groups, acute caffeine increased systolic and diastolic blood pressure by a few mmHg.
Extending caffeine treatment in preterm infants reduced time spent with oxygen saturation <90% (intermittent hypoxia) compared with usual care.
In healthy male adults, single doses of stimulants (including caffeine 200 mg as one arm) improved multiple memory measures and altered resting‑state functional connectivity; changes in connectivity related to memory enhancement.
In a double-blind crossover, 4 mg/kg caffeine increased perceived activation and pupil size and reduced variability of accommodative response, without altering accommodation accuracy.
In people with type 1 diabetes, habitual caffeine intake was positively associated with skin intrinsic fluorescence (SIF) measures, and this was replicated in an independent cohort.
Large PET imaging series (6087 scans) showed that even low serum caffeine reduces quantitative myocardial stress perfusion and coronary flow reserve during vasodilator stress, and in a small fraction alters coronary flow capacity interpretation (possible false negatives/positives).
Preoperative 200 mg oral caffeine reduced the incidence of post-spinal hypotension and lowered vasopressor (ephedrine) requirements in adults undergoing lower limb orthopedic surgery.
In 90 preterm neonates (1250–2000 g), prophylactic caffeine reduced duration of NCPAP and lowered apnea and IVH incidence compared to control.
During 50 h sleep deprivation, strategic caffeine gum maintained neurobehavioural performance; higher salivary alpha-amylase (sAA) was associated with better PVT response speed in the caffeine group, though the association was weaker than in placebo.
Bright light combined with 100 mg caffeine gum improved driving performance and subjective sleepiness more than caffeine alone in sleep-restricted young drivers.
Among 194 patients undergoing dipyridamole stress testing, ~19% who denied caffeine exposure had detectable serum caffeine; detectable caffeine was associated with higher 24-month adverse cardiac events.
In healthy young adults, single doses of caffeine (3 and 6 mg/kg) increased fat oxidation during moderate-intensity cycling, and this effect did not differ by CYP1A2 genotype.
In trained male athletes, caffeine mouth rinse improved hand and foot reaction time, with the highest concentration (2.4%) giving the largest benefit.
In adults given caffeine vs placebo across weeks, caffeine produced few modest EEG changes (theta and alpha) and evidence of withdrawal/withdrawal reversal effects on EEG and mood.
In ventilated preterm infants, higher caffeine doses reduced short-term apnoea and improved oxygenation metrics but did not change extubation failure rates.
A 3 mg/kg dose of caffeine improved reaction times on a cognitive task, including during a fatiguing motor dual-task, without changing motor force or endurance.
About 3 mg/kg caffeine increased parasympathetic reactivation after submaximal exercise (60–300 s post-exercise) but did not alter resting cardiac parasympathetic modulation or HRV threshold.
In obese adolescents on a calorie-restricted diet, an ephedrine+caffeine pill produced much larger weight, BMI, and body-fat loss over 20 weeks than placebo.
Survey of 4,271 US college students found that mixing energy drinks with alcohol was common and associated with higher heavy drinking and more alcohol-related harms.
In a double-blind crossover study, moderate caffeine during 38 h wakefulness reduced recovery-night total sleep time and N3 sleep and worsened sleep continuity and EEG slow-wave power.
In 58 adults, 12 weeks of catechin- and caffeine-containing green tea supplementation did not change gut microbiota composition or diversity nor body composition versus placebo.
Adding low-dose caffeine (60 mg) to patients' antidepressant regimens reduced depression scores, improved cognition, and normalized stress-hormone response.
In 27 pregnant women (19 controls, 8 with GDM) in a randomized crossover trial, acute caffeine (3 mg/kg) impaired insulin sensitivity and raised glucose and C-peptide AUCs in women with gestational diabetes but not in controls.
Acute ingestion of black tea increased aortic stiffness briefly and both black and green tea raised wave reflections; effects were smaller than those produced by isolated caffeine.
In 110 men, acute caffeine raised systolic and diastolic blood pressure modestly (~+4 mmHg and +3 mmHg) and increased plasma adrenaline.
Preoperative Novafen (acetaminophen + ibuprofen + 40 mg caffeine) produced small reductions in postoperative pain scores at several timepoints versus placebo.
A nonprescription combination including caffeine (with acetaminophen and aspirin) provided greater pain relief and functional improvement than placebo in OTC-appropriate migraine sufferers.
After outpatient general surgery, analgesia was similar between the codeine+acetaminophen+caffeine regimen and acetaminophen+ibuprofen, but the codeine+caffeine group had more side effects and lower satisfaction.
Daily caffeine 250 mg (alone or with DMAA) for 12 weeks produced no statistically significant adverse changes in measured clinical or laboratory outcomes.
An 80 mg-caffeine energy drink improved some working-memory and attention measures and partially antagonised alcohol-induced errors on select tasks at specific timepoints.
In overweight adults, 8 weeks of caffeinated coffee increased adiponectin and IL‑6 while decaffeinated coffee lowered fetuin‑A; no change in glucose tolerance.
Neonatal caffeine therapy was not associated with differences in sleep duration or sleep-disordered breathing at school age.
Adding caffeine to ibuprofen sped pain relief onset and increased analgesic effect at 45–60 minutes after single-dose administration, with few adverse events.
In older adults with SCD or MCI, daily matcha (contains caffeine, theanine, catechins) for 12 months improved emotional perception/social acuity and showed a trend toward better sleep quality, but did not change primary global cognitive scores.
Early caffeine in 59 preterm infants reduced ventilator needs, shortened respiratory support times, lowered VAP, and reduced post-extubation apnea.
Single 6 mg/kg caffeine increased blood pressure and tidal volume and raised plasma caffeine concentrations; epinephrine rose in able-bodied and paraplegic but not tetraplegic participants, with limited HRV changes.
In healthy elderly adults, 6 mg/kg caffeine increased plasma epinephrine, free fatty acids, and lactate (percent increases consistent at rest, 5 min, and exhaustion), and increased insulin-resistance measures.
During 40.5 h sleep deprivation, caffeine reduced sleep drive compared with placebo but did not improve sleep-related recovery measures; other stimulants had differing effects.
Two-week ingestion of caffeine capsules (≈870 mg/day) produced a small but significant increase in fasting plasma homocysteine (~+0.4 µmol/L, ≈+5%), indicating caffeine partly contributes to coffee's homocysteine-raising effect.
In healthy adults, increasing caffeine doses impaired insulin sensitivity and raised insulin, C-peptide, and glucose responses in a dose-dependent way.
In 27 pregnant women (19 controls, 8 with GDM) in a randomized crossover trial, acute caffeine (3 mg/kg) impaired insulin sensitivity and raised glucose and C-peptide AUCs in women with gestational diabetes but not in controls.
In infants with bronchiolitis-associated apnea, a single IV caffeine dose did not shorten time to a 24-hour apnea-free period compared with placebo.
Late preterm infants were randomized to placebo or varying doses of caffeine citrate; overnight oximetry measured intermittent hypoxaemia and cardiorespiratory outcomes.
A 250-ml Red Bull (80 mg caffeine) consumed during a short break improved driving stability and reduced sleepiness for about 2 hours compared with placebo or no break.
Acute multi-ingredient preworkout supplements (one formulation contained caffeine) modestly improved anaerobic power and some endurance and vascular measures versus placebo; caffeine was one of several active ingredients.
In competitive male athletes, caffeine had no overall effect on strength/power, but 4 mg/kg caffeine reduced handgrip strength by ~12.8% in individuals with the CYP1A2 CC genotype.
In 30 resistance-trained men, acute caffeine (6 mg/kg) increased blood lactate during resistance exercise, with greater lactate elevations in carriers of the MCT1 A allele (TA+AA) versus TT genotype; potassium responses varied by genotype and intervention.
In 28 trained young adults randomized to creatine, caffeine, creatine+caffeine, or placebo during 6 weeks training, creatine increased knee extensor thickness but caffeine produced no clear benefits.
Sixty abstinent coffee drinkers received decaf with 0 or 280 mg caffeine crossed with expectancy instructions; caffeine improved vigilance and psychomotor speed and expectancy altered subjective and some behavioral outcomes.
In 36 volunteers, drinking unfiltered natural coffee for 4 weeks raised plasma homocysteine, whereas modified (filtered/treated) coffee tended to lower it; other vitamins not notably reported.
In 320 women with moderate-to-severe dysmenorrhoea, paracetamol (1 g) plus caffeine (130 mg) provided greater pain relief at 2 hours and better relief of cramping and backache than paracetamol alone, caffeine alone, or placebo.
In a 6-week double-blind randomized free-living trial, adding caffeine to a sugar-sweetened beverage increased ad libitum consumption compared with the non-caffeinated version.
In 93 college-age moderate caffeine users, caffeine improved initial acquisition (accuracy and latency) on a proprioceptive force-discrimination learning task but did not improve performance beyond normal practice.
Caffeine improved short-duration arm-crank power in paraplegic participants but showed no clear ergogenic effect in tetraplegic or able-bodied groups.
Caffeine improved short-duration arm-crank power in paraplegic participants but showed no clear ergogenic effect in tetraplegic or able-bodied groups.
In 100 male athletes performing 10-km cycling trials, 4 mg/kg caffeine improved endurance time selectively in individuals with HTR2A CC genotype who were also CYP1A2 fast metabolizers.
In a multicenter RCT of 200 mg twice daily caffeine vs placebo in Parkinson’s disease (n=121), caffeine did not improve motor scores and had minor adverse effects on cognition and dyskinesia.
In adults 50–69, single-dose caffeine shortened reaction times on several cognitive tasks and 12-week caffeine or matcha intake preserved MMSE-J scores versus placebo; matcha additionally improved work on a stress task with continuous intake.
Preprocedural oral caffeine (5 mg/kg) increased PVC counts during isoproterenol washout, increased PVC count fluctuation, and shortened procedure and ablation times during catheter ablation.
Single 6 mg/kg caffeine dose before a triathlon slightly improved swim and overall completion times and increased postexercise cortisol and peak blood lactate.
A single 275 mg caffeine dose (or 150 mg caffeine + 125 mg theacrine) produced modest improvements in some reaction-time measures and trended to increase time-to-exhaustion versus placebo.
Daily ingestion of a caffeine-containing supplement (≈201 mg/day) during 8 weeks of aerobic training produced no additional improvements in VO2peak, time to exhaustion, or body composition versus placebo.
Acute caffeine (6 mg/kg) improved countermovement jump performance and total repetitions in strength endurance tests regardless of habitual caffeine intake level.
During 40-h sleep deprivation, caffeine preserved simple response output but did not prevent many executive-function deficits on a random number task.
Adding caffeine to a multi-drug probe cocktail did not produce meaningful metabolic interactions for measured enzyme probe drugs, though a small increase in one flurbiprofen metric occurred.
Male collegiate basketball players doing 6 weeks of plyometric training improved performance and physiology; ingesting caffeine 1 h before sessions (especially 6 mg/kg) produced slightly larger and more uniform adaptations than placebo.
In 120 preterm infants, higher-dose caffeine citrate reduced extubation failure and apnea frequency/duration but increased episodes of tachycardia.
In patients undergoing regadenoson-stress SPECT MPI, ingestion of caffeine (200–400 mg) 90 minutes before testing reduced the number and severity of detected reversible perfusion defects and altered BP/HR responses.
A brief school-based intervention modestly reduced electronic media use at night but did not change adolescents' caffeine consumption, sleep duration, or secondary outcomes.
Stopping coffee in iron-deficient Guatemalan toddlers increased night and total sleep but did not change cognitive test scores.
Chronic (3 or 6 mg/kg/day) and acute caffeine did not alter most fluid-electrolyte, thermoregulatory or cardiovascular responses during a heat exercise test, though one treatment group had longer tolerance time.
On-demand 100 mg caffeine before intercourse increased ejaculation latency and sexual satisfaction versus placebo.
Caffeine 100 mg in the fixed-dose combination was rapidly absorbed and did not alter ibuprofen pharmacokinetics; ibuprofen PK comparable with/without caffeine.
In women with urinary incontinence, reducing fluid intake improved some symptoms, but switching from caffeinated to decaffeinated drinks did not improve urinary symptoms.
Large PET imaging series (6087 scans) showed that even low serum caffeine reduces quantitative myocardial stress perfusion and coronary flow reserve during vasodilator stress, and in a small fraction alters coronary flow capacity interpretation (possible false negatives/positives).
Preoperative 200 mg oral caffeine reduced the incidence of post-spinal hypotension and lowered vasopressor (ephedrine) requirements in adults undergoing lower limb orthopedic surgery.
In a randomized crossover trial, a 75 mg caffeine positive-control produced consistent alerting and performance-enhancing effects versus placebo in healthy adults (n=72).
In 90 preterm neonates (1250–2000 g), prophylactic caffeine reduced duration of NCPAP and lowered apnea and IVH incidence compared to control.
In children who habitually consume caffeine, a 50 mg dose after overnight abstinence restored cognitive accuracy, prevented withdrawal headache, and increased alertness; non/low-consumers showed no clear benefit.
In preterm infants <33 weeks, caffeine reduced apnea frequency during the first week of therapy and appeared advantageous over theophylline early on.
In preterm infants with primary apnea, a higher maintenance dose of caffeine citrate improved apnea control and ventilator weaning success without increasing measured side effects.
Higher caffeinated coffee/caffeine intake was associated with higher plasma SHBG and lower type 2 diabetes risk; adjustment for SHBG attenuated the diabetes association.
In 240 preterm neonates with apnea, caffeine citrate was similarly effective to aminophylline overall, with caffeine showing a lower risk of tachycardia and lower mean heart rate.
Among 194 patients undergoing dipyridamole stress testing, ~19% who denied caffeine exposure had detectable serum caffeine; detectable caffeine was associated with higher 24-month adverse cardiac events.
Experimental induction of caffeine craving impaired memory performance and some metacognitive judgments compared to control.
Both domestic and imported caffeine citrate were similarly safe and effective for treating apnea in preterm infants.
300 mg caffeine worsened motor steadiness (more errors) in healthy adult females.
Caffeine has a long half-life in preterm infants and many infants had pathologic apnea days after stopping caffeine.
A single cup-equivalent dose after overnight abstinence increased energetic mood and improved psychomotor performance; additional spaced doses added little.
Caffeine improved neonatal respiratory compliance and reduced oxygen needs earlier than theophylline.
Combined caffeine and glucose did not change behavioral sustained attention but reduced activation in attention-related brain regions, suggesting increased neural efficiency.
NaHCO3 and caffeine each improved some aspects of repeated-sprint performance, but their coingestion did not produce a synergistic benefit.
In very preterm infants randomized to early high- vs standard-dose caffeine, high-dose was associated with higher rates of cerebellar hemorrhage and subtle neonatal neurobehavioral differences but no detectable 2-year developmental differences in this pilot trial.
In ventilated preterm infants, higher caffeine doses reduced short-term apnoea and improved oxygenation metrics but did not change extubation failure rates.
Higher maintenance caffeine citrate dose (10 mg/kg/day vs 5 mg/kg/day) reduced extubation failure, apnea days and shortened time to extubation in very preterm infants.
In 120 preterm infants, higher-dose caffeine citrate reduced extubation failure and apnea frequency/duration but increased episodes of tachycardia.
In 27 male rugby players, 3 mg/kg caffeine (capsule, gum, or mouth rinse) produced limited effects: a small increase in countermovement-jump height and one-set squat endurance, but most strength/power measures were unchanged.
In 26 recreationally trained men, acute caffeine (6 mg/kg) increased countermovement jump height versus control and versus placebo; maximal power output was unchanged.
In 40 young adults, 36 h sleep deprivation impaired temporal (recency) memory; a single 350 mg caffeine dose reduced subjective sleepiness but did not restore temporal memory performance.
In 40 young adults, 36 h sleep deprivation impaired temporal (recency) memory; a single 350 mg caffeine dose reduced subjective sleepiness but did not restore temporal memory performance.
Amounts of caffeine plus theobromine present in normal portions of chocolate improved energetic arousal and cognitive function versus placebo/white chocolate.
In 20 mild hypertensive and 12 normotensive men (total 32), caffeine increased blood pressure and rate-pressure product at rest and during exercise, raising cardiac workload in hypertensives.
During an 18-km run, sports drinks increased gastrointestinal complaint incidence versus water; adding caffeine (150 mg/L) to the sports drink did not affect running performance or GI complaints compared with the sports drink without caffeine.
Daily caffeine challenges produced small but persistent increases in ambulatory blood pressure in some habitual consumers after repeated intake.
Daily use of a shampoo containing caffeine plus DMG‑Na reduced hair shedding and improved hair growth measures versus placebo after 6 months.
Preoperative Novafen (acetaminophen + ibuprofen + 40 mg caffeine) produced small reductions in postoperative pain scores at several timepoints versus placebo.
An 80 mg-caffeine energy drink improved some working-memory and attention measures and partially antagonised alcohol-induced errors on select tasks at specific timepoints.
In very preterm infants randomized to higher vs lower caffeine citrate dosing, there was a borderline higher mean cognitive score at 1 year in the high-dose group but no clear adverse developmental, temperament, or behavior effects.
A combination containing caffeine (AAC) provided faster and greater migraine pain relief and symptom improvement than placebo in both menstruation-associated and non-menstrual migraine.
Diclofenac softgel plus 100 mg caffeine provided greater headache relief at 60 minutes versus placebo in migraineurs; diclofenac alone showed non-significant differences (study underpowered).
In older adults with SCD or MCI, daily matcha (contains caffeine, theanine, catechins) for 12 months improved emotional perception/social acuity and showed a trend toward better sleep quality, but did not change primary global cognitive scores.
In 21 elite basketball players, 3 mg/kg caffeine did not improve dribbling speed; most players were non-responders.
In 101 children/adolescents, caffeine produced larger cardiovascular responses in boys than girls after puberty and responses varied across the menstrual cycle in postpubertal girls.
Night-shift simulation: caffeine (2 mg/kg at two nighttime points) reduced physiological sleep tendency at night but did not change task performance or daytime sleep measures.
Placebo-caffeine study (participants believed they drank caffeinated water): social influence moderated responses—confirming confederate increased subjective alertness, reduced cognitive interference and raised product endorsement; disconfirming confederate produced larger SBP decreases.
In a double-blind trial, 300 mg caffeine caused people to generate fewer options but to start generating options faster; caffeine did not affect subsequent choice selection.
Topical 2% caffeine alone did not slow myopia progression over 12 months; atropine (0.02%) slowed progression and caffeine did not alter atropine's efficacy when combined.
In moderately trained CrossFit athletes, different acute caffeine doses (3, 6, 9 mg/kg) did not produce consistent statistically superior performance vs placebo, though 6 mg/kg showed the largest practical improvement in some measures.
A moderate caffeine dose (3 mg/kg) improved endurance cycling time similarly in women and men (~4–4.6% improvement).
IV caffeine after spinal anesthesia reduced headache severity, fewer moderate/severe headaches, and reduced analgesic needs.
Adding caffeine to paracetamol sped absorption (shorter Tmax), increased Cmax and Ka, and prolonged t1/2—effects greater in hepatic patients.
Late preterm infants were randomized to placebo or varying doses of caffeine citrate; overnight oximetry measured intermittent hypoxaemia and cardiorespiratory outcomes.
Early prophylactic caffeine in very preterm infants improved white-matter microstructure on MRI and reduced apnea/ventilation needs versus placebo.
In very preterm infants, caffeine was linked to microstructural changes in white matter but not to changes in brain volumes.
Caffeine combined with work stress produced additive increases in blood pressure in medical students, especially those at high familial risk for hypertension.
In 48 habitual caffeine consumers deprived 24 h, caffeine (200 mg) improved aspects of cognition and reduced fatigue; taurine and glucose had different or no effects.
In 48 habitual caffeine consumers deprived 24 h, caffeine (200 mg) improved aspects of cognition and reduced fatigue; taurine and glucose had different or no effects.
In 320 women with moderate-to-severe dysmenorrhoea, paracetamol (1 g) plus caffeine (130 mg) provided greater pain relief at 2 hours and better relief of cramping and backache than paracetamol alone, caffeine alone, or placebo.
In a double-blind crossover trial, caffeine taken before a mental stressor amplified cardiovascular/hemodynamic stress responses in both men and women.
In a 6-week double-blind randomized free-living trial, adding caffeine to a sugar-sweetened beverage increased ad libitum consumption compared with the non-caffeinated version.
In adults with tinnitus, a single 300 mg caffeine dose did not produce clinically meaningful changes in tinnitus-related discomfort or psychoacoustic measures compared to placebo.
In 93 college-age moderate caffeine users, caffeine improved initial acquisition (accuracy and latency) on a proprioceptive force-discrimination learning task but did not improve performance beyond normal practice.
In a double-blind experiment (regular n=92, low/non-consumers n=89), acute stress slightly increased hallucination-like experiences; 100 mg caffeine produced a small time-dependent effect on threat-related recall bias.
In 51 patients with systolic heart failure, acute high-dose caffeine (total 500 mg) did not increase ventricular or supraventricular premature beats or exercise-derived arrhythmias compared with placebo.
In a multicenter RCT of 200 mg twice daily caffeine vs placebo in Parkinson’s disease (n=121), caffeine did not improve motor scores and had minor adverse effects on cognition and dyskinesia.
In 27 healthy volunteers, 50 mg caffeine improved alertness and attention-switching accuracy; combined L-theanine (100 mg) plus caffeine improved speed and accuracy on attention-switching and reduced distraction in memory tasks.
Preprocedural oral caffeine (5 mg/kg) increased PVC counts during isoproterenol washout, increased PVC count fluctuation, and shortened procedure and ablation times during catheter ablation.
Single 6 mg/kg caffeine dose before a triathlon slightly improved swim and overall completion times and increased postexercise cortisol and peak blood lactate.
Two randomized crossover trials in men showed beverages containing green tea catechins and coffee chlorogenic acids (with matched caffeine) raised postprandial GLP-1, lowered GIP, and reduced post-meal blood glucose compared to placebo.
Acute ingestion of green or black tea produced larger short-term increases in clinic systolic and diastolic blood pressure than caffeine-matched water, but regular 7-day tea consumption did not significantly change 24-h ambulatory blood pressure.
Higher maintenance caffeine citrate dose (10 mg/kg/day vs 5 mg/kg/day) reduced extubation failure, apnea days and shortened time to extubation in very preterm infants.
In healthy adults, caffeinated coffee acutely delayed insulin rise and increased postprandial glucose exposure compared with water; effects varied by sex and BMI.
In 54 active men, creatine loading with or without added caffeine (or coffee) did not provide additional improvements in strength or sprint performance compared with placebo over 5 days.
In patients undergoing regadenoson-stress SPECT MPI, ingestion of caffeine (200–400 mg) 90 minutes before testing reduced the number and severity of detected reversible perfusion defects and altered BP/HR responses.
A brief school-based intervention modestly reduced electronic media use at night but did not change adolescents' caffeine consumption, sleep duration, or secondary outcomes.
A 480 mg oral caffeine challenge induced panic attacks in a higher proportion of patients with panic disorder and depression with panic attacks than in depressed-only patients or healthy controls.
A 480 mg oral caffeine challenge induced panic attacks in a majority of panic disorder (60.7%) and performance social anxiety disorder (52.6%) patients, in fewer GSAD patients (16%), and in no controls.
Caffeine gum prevented the rise in risky behaviour and reduced self-reported impulsivity during 75 hours of continuous sleep deprivation.
Extending caffeine treatment in preterm infants reduced time spent with oxygen saturation <90% (intermittent hypoxia) compared with usual care.
In healthy male adults, single doses of stimulants (including caffeine 200 mg as one arm) improved multiple memory measures and altered resting‑state functional connectivity; changes in connectivity related to memory enhancement.
In a double-blind crossover, 4 mg/kg caffeine increased perceived activation and pupil size and reduced variability of accommodative response, without altering accommodation accuracy.
A 250 mg caffeine drink increased pupil size and amplitude of accommodation over 90 minutes in young adults.
Overweight subjects lost weight on a very low energy diet then during 3-month maintenance received a green tea–caffeine mixture or placebo; effects depended on habitual caffeine intake.
Follow-up of infants randomized to neonatal caffeine or placebo showed lower rates of developmental coordination disorder at age 5 in the caffeine group.
Caffeine reduced sleepiness and improved motor performance (tapping and reaction times); improvements in mental alertness and cognition were mainly seen in medium-high consumers and were limited in frequent consumers.
After implant surgery, acetaminophen+caffeine produced less early postoperative swelling but more pain at 3–12 h compared with acetaminophen+codeine.
In 100 healthy drivers, a single 200 mg caffeine dose improved some executive/cognitive test performance and shortened brake reaction time versus placebo.
In adolescent male athletes, 6 mg/kg caffeine increased endurance performance (Yo-Yo IR1 distance) and VO2max in ACE II and DI genotype carriers but not in DD carriers; heart rate and perceived exertion also rose in I-allele carriers.
In 90 preterm neonates (1250–2000 g), prophylactic caffeine reduced duration of NCPAP and lowered apnea and IVH incidence compared to control.
Ingesting 5 mg/kg caffeine produced small but statistically significant faster 5-km times in both well-trained and recreational runners (~1% improvement).
During 50 h sleep deprivation, strategic caffeine gum maintained neurobehavioural performance; higher salivary alpha-amylase (sAA) was associated with better PVT response speed in the caffeine group, though the association was weaker than in placebo.
Among 194 patients undergoing dipyridamole stress testing, ~19% who denied caffeine exposure had detectable serum caffeine; detectable caffeine was associated with higher 24-month adverse cardiac events.
A 7-day multi-ingredient supplement (including vitamin D) reduced pain severity and musculoskeletal discomfort vs baseline and performed similarly or better than acetaminophen in this small crossover trial.
In depressed patients receiving active or sham dmPFC iTBS, higher habitual caffeine intake was associated with greater symptom improvement in the active group.
Large randomized double-blind trial showing that adding caffeine to ibuprofen improved relief of tension-type headache vs components or placebo.
In 24 habitual caffeine consumers and 24 non-consumers, acute caffeine (75 or 150 mg) improved reaction times, vigilance and working memory and reduced self-rated mental fatigue and increased alertness regardless of habitual use.
Both domestic and imported caffeine citrate were similarly safe and effective for treating apnea in preterm infants.
300 mg caffeine worsened motor steadiness (more errors) in healthy adult females.
Caffeine has a long half-life in preterm infants and many infants had pathologic apnea days after stopping caffeine.
A single cup-equivalent dose after overnight abstinence increased energetic mood and improved psychomotor performance; additional spaced doses added little.
Caffeine improved neonatal respiratory compliance and reduced oxygen needs earlier than theophylline.
In trained male athletes, caffeine mouth rinse improved hand and foot reaction time, with the highest concentration (2.4%) giving the largest benefit.
In adults given caffeine vs placebo across weeks, caffeine produced few modest EEG changes (theta and alpha) and evidence of withdrawal/withdrawal reversal effects on EEG and mood.
In ventilated preterm infants, higher caffeine doses reduced short-term apnoea and improved oxygenation metrics but did not change extubation failure rates.
A 3 mg/kg dose of caffeine improved reaction times on a cognitive task, including during a fatiguing motor dual-task, without changing motor force or endurance.
In 27 male rugby players, 3 mg/kg caffeine (capsule, gum, or mouth rinse) produced limited effects: a small increase in countermovement-jump height and one-set squat endurance, but most strength/power measures were unchanged.
Adding low-dose caffeine (60 mg) to patients' antidepressant regimens reduced depression scores, improved cognition, and normalized stress-hormone response.
Amounts of caffeine plus theobromine present in normal portions of chocolate improved energetic arousal and cognitive function versus placebo/white chocolate.
In 49 moderate–high habitual consumers, a second 1.2 mg/kg caffeine dose improved cognitive performance and mood only after 8 h abstinence and raised blood pressure after 8 h; shorter abstinence produced some adverse effects on hand steadiness.
In 49 moderate–high habitual consumers, a second 1.2 mg/kg caffeine dose improved cognitive performance and mood only after 8 h abstinence and raised blood pressure after 8 h; shorter abstinence produced some adverse effects on hand steadiness.
Knowing about a possible placebo had limited effect overall; uninformed participants showed some caffeine-induced increases in diastolic blood pressure and vigor and impaired hand steadiness at higher dose.
Acute ingestion of black tea increased aortic stiffness briefly and both black and green tea raised wave reflections; effects were smaller than those produced by isolated caffeine.
During an 18-km run, sports drinks increased gastrointestinal complaint incidence versus water; adding caffeine (150 mg/L) to the sports drink did not affect running performance or GI complaints compared with the sports drink without caffeine.
A multi-ingredient product (including caffeine and ephedrine) produced modest additional weight loss (~1.5 kg) and greater reductions in BMI and waist circumference versus placebo over 12 weeks; no BP or pulse increases were observed.
In healthy adults, increasing caffeine doses impaired insulin sensitivity and raised insulin, C-peptide, and glucose responses in a dose-dependent way.
Daily caffeine challenges produced small but persistent increases in ambulatory blood pressure in some habitual consumers after repeated intake.
Preoperative Novafen (acetaminophen + ibuprofen + 40 mg caffeine) produced small reductions in postoperative pain scores at several timepoints versus placebo.
Daily caffeine 250 mg (alone or with DMAA) for 12 weeks produced no statistically significant adverse changes in measured clinical or laboratory outcomes.
An 80 mg-caffeine energy drink improved some working-memory and attention measures and partially antagonised alcohol-induced errors on select tasks at specific timepoints.
Acute caffeine (5 mg/kg) increased squat- and countermovement-jump heights and improved some force/velocity execution metrics in collegiate athletes.
Acute caffeine (5 mg/kg) increased squat- and countermovement-jump heights and improved some force/velocity execution metrics in collegiate athletes.
In very preterm infants randomized to higher vs lower caffeine citrate dosing, there was a borderline higher mean cognitive score at 1 year in the high-dose group but no clear adverse developmental, temperament, or behavior effects.
Repeated caffeine gum (up to 200 mg every 2 hours) reduced vigilance lapses during an extended wake period and 200 mg preserved baseline performance overnight.
In older adults with SCD or MCI, daily matcha (contains caffeine, theanine, catechins) for 12 months improved emotional perception/social acuity and showed a trend toward better sleep quality, but did not change primary global cognitive scores.
In tactical males, 300 mg caffeine and a 150 mg caffeine + methylliberine + theacrine combo similarly improved vigilance reaction time; caffeine raised DBP vs placebo while the combo raised SBP but not DBP.
Early caffeine in 59 preterm infants reduced ventilator needs, shortened respiratory support times, lowered VAP, and reduced post-extubation apnea.
In 21 elite basketball players, 3 mg/kg caffeine did not improve dribbling speed; most players were non-responders.
In trained women habituated to caffeine, acute caffeine (3 and 6 mg/kg) increased 1RM strength (dose-response) and 6 mg/kg increased time under tension; no clear change in repetitions or power measures.
Night-shift simulation: caffeine (2 mg/kg at two nighttime points) reduced physiological sleep tendency at night but did not change task performance or daytime sleep measures.
Placebo-caffeine study (participants believed they drank caffeinated water): social influence moderated responses—confirming confederate increased subjective alertness, reduced cognitive interference and raised product endorsement; disconfirming confederate produced larger SBP decreases.
A 6-month randomized trial of an herbal ephedra/caffeine product produced greater weight loss than placebo and increased some GI and sleep-related side effects.
A combined caffeine+ephedra supplement raised resting metabolic rate and produced greater weight and fat loss than placebo over 12 weeks.
A multi-ingredient product (including caffeine and ephedrine) produced modest additional weight loss (~1.5 kg) and greater reductions in BMI and waist circumference versus placebo over 12 weeks; no BP or pulse increases were observed.
An 8-week randomized trial of an herbal mix (includes 240 mg/day caffeine) produced greater short-term weight and fat loss but more withdrawals and side effects.
In a double-blind trial, 300 mg caffeine caused people to generate fewer options but to start generating options faster; caffeine did not affect subsequent choice selection.
Two-week ingestion of caffeine capsules (≈870 mg/day) produced a small but significant increase in fasting plasma homocysteine (~+0.4 µmol/L, ≈+5%), indicating caffeine partly contributes to coffee's homocysteine-raising effect.
Late preterm infants were randomized to placebo or varying doses of caffeine citrate; overnight oximetry measured intermittent hypoxaemia and cardiorespiratory outcomes.
Acute multi-ingredient preworkout supplements (one formulation contained caffeine) modestly improved anaerobic power and some endurance and vascular measures versus placebo; caffeine was one of several active ingredients.
In 28 trained young adults randomized to creatine, caffeine, creatine+caffeine, or placebo during 6 weeks training, creatine increased knee extensor thickness but caffeine produced no clear benefits.
Sixty abstinent coffee drinkers received decaf with 0 or 280 mg caffeine crossed with expectancy instructions; caffeine improved vigilance and psychomotor speed and expectancy altered subjective and some behavioral outcomes.
Over six pairings, drinks paired with 19 mg caffeine + 250 mg theobromine became liked more than placebo‑paired drinks, suggesting methylxanthines increase acquired liking.
In 36 volunteers, drinking unfiltered natural coffee for 4 weeks raised plasma homocysteine, whereas modified (filtered/treated) coffee tended to lower it; other vitamins not notably reported.
In adults with tinnitus, a single 300 mg caffeine dose did not produce clinically meaningful changes in tinnitus-related discomfort or psychoacoustic measures compared to placebo.
Perioperative substitution of patients' usual caffeine intake prevented postoperative headaches compared with placebo in habitual consumers.
In a multicenter RCT of 200 mg twice daily caffeine vs placebo in Parkinson’s disease (n=121), caffeine did not improve motor scores and had minor adverse effects on cognition and dyskinesia.
In adults 50–69, single-dose caffeine shortened reaction times on several cognitive tasks and 12-week caffeine or matcha intake preserved MMSE-J scores versus placebo; matcha additionally improved work on a stress task with continuous intake.
Single 6 mg/kg caffeine dose before a triathlon slightly improved swim and overall completion times and increased postexercise cortisol and peak blood lactate.
A single 275 mg caffeine dose (or 150 mg caffeine + 125 mg theacrine) produced modest improvements in some reaction-time measures and trended to increase time-to-exhaustion versus placebo.
A mixed herbal preparation containing Yerba Maté and Guarana (sources of caffeine) delayed gastric emptying and produced greater short-term weight loss versus placebo over 45 days.
Daily ingestion of a caffeine-containing supplement (≈201 mg/day) during 8 weeks of aerobic training produced no additional improvements in VO2peak, time to exhaustion, or body composition versus placebo.
Sleep restriction (5 h) impaired tennis serving accuracy; a single 80 mg caffeine dose did not restore accuracy in semi-professional players.
Acute caffeine (6 mg/kg) improved countermovement jump performance and total repetitions in strength endurance tests regardless of habitual caffeine intake level.
During 40-h sleep deprivation, caffeine preserved simple response output but did not prevent many executive-function deficits on a random number task.
Early caffeine did not shorten time to first successful extubation in ventilated preterm infants and showed a non-significant trend toward higher mortality in the caffeine group.
Adding caffeine to a multi-drug probe cocktail did not produce meaningful metabolic interactions for measured enzyme probe drugs, though a small increase in one flurbiprofen metric occurred.
Male collegiate basketball players doing 6 weeks of plyometric training improved performance and physiology; ingesting caffeine 1 h before sessions (especially 6 mg/kg) produced slightly larger and more uniform adaptations than placebo.
In resistance-trained males, acute caffeine (3 mg/kg) produced no significant changes in bench-press, jump, or Wingate outcomes related to habitual caffeine intake.
Chronic (3 or 6 mg/kg/day) and acute caffeine did not alter most fluid-electrolyte, thermoregulatory or cardiovascular responses during a heat exercise test, though one treatment group had longer tolerance time.
Caffeine 100 mg in the fixed-dose combination was rapidly absorbed and did not alter ibuprofen pharmacokinetics; ibuprofen PK comparable with/without caffeine.
In women with urinary incontinence, reducing fluid intake improved some symptoms, but switching from caffeinated to decaffeinated drinks did not improve urinary symptoms.
In healthy male adults, single doses of stimulants (including caffeine 200 mg as one arm) improved multiple memory measures and altered resting‑state functional connectivity; changes in connectivity related to memory enhancement.
In sleep-deprived adults, stimulants had different effects: caffeine improved alertness measures but did not enhance cartoon humor appreciation.
In sleep-deprived adults, stimulants had different effects: caffeine improved alertness measures but did not enhance cartoon humor appreciation.
In resistance-trained males, acute caffeine (3 mg/kg) produced no significant changes in bench-press, jump, or Wingate outcomes related to habitual caffeine intake.
In resistance-trained males, acute caffeine (3 mg/kg) produced no significant changes in bench-press, jump, or Wingate outcomes related to habitual caffeine intake.
In people with type 1 diabetes, habitual caffeine intake was positively associated with skin intrinsic fluorescence (SIF) measures, and this was replicated in an independent cohort.
Paracetamol-caffeine reduced separator-related pain compared with placebo but did not improve overall oral-health-related quality of life.
Single 600 mg slow-release caffeine decreased calmness and prolonged sleep onset but did not change alertness the next day.
In healthy young males, 200 mg caffeine improved sustained attention (shorter reaction time) but showed no robust effects on most other cognitive domains or subjective fatigue.
In endurance-trained adults, 3 mg/kg caffeine increased mean power in a 6-min time trial (~+12 W) but did not add to creatine effects on 15-s sprint power.
During 50 h sleep deprivation, strategic caffeine gum maintained neurobehavioural performance; higher salivary alpha-amylase (sAA) was associated with better PVT response speed in the caffeine group, though the association was weaker than in placebo.
Higher caffeinated coffee/caffeine intake was associated with higher plasma SHBG and lower type 2 diabetes risk; adjustment for SHBG attenuated the diabetes association.
Large randomized double-blind trial showing that adding caffeine to ibuprofen improved relief of tension-type headache vs components or placebo.
Adolescents exposed to a novel soda with 2 mg/kg caffeine showed increased liking over repeated exposures and reduced bitterness perception.
Experimental induction of caffeine craving impaired memory performance and some metacognitive judgments compared to control.
In 24 habitual caffeine consumers and 24 non-consumers, acute caffeine (75 or 150 mg) improved reaction times, vigilance and working memory and reduced self-rated mental fatigue and increased alertness regardless of habitual use.
In middle-aged adults, 2-week intake of a tea catechin beverage (containing ~88 mg caffeine) increased energy expenditure after ingestion by ~96 kJ/day (~1.7%) versus a caffeinated placebo beverage; fasting RMR did not change.
In healthy young adults, 75 mg caffeine reduced prefrontal oxygenated haemoglobin and increased deoxygenated haemoglobin and improved some reaction-time and mood measures; co‑administration with L‑theanine abolished the oxy‑Hb reduction and removed the behavioural benefits.
In trained male athletes, caffeine mouth rinse improved hand and foot reaction time, with the highest concentration (2.4%) giving the largest benefit.
In adults given caffeine vs placebo across weeks, caffeine produced few modest EEG changes (theta and alpha) and evidence of withdrawal/withdrawal reversal effects on EEG and mood.
In very preterm infants randomized to early high- vs standard-dose caffeine, high-dose was associated with higher rates of cerebellar hemorrhage and subtle neonatal neurobehavioral differences but no detectable 2-year developmental differences in this pilot trial.
In trained male boxers, adding 3 mg/kg caffeine to a PAPE protocol increased the magnitude of Wingate performance gains and uniquely increased peak power and perceived power versus control.
A 3 mg/kg dose of caffeine improved reaction times on a cognitive task, including during a fatiguing motor dual-task, without changing motor force or endurance.
About 3 mg/kg caffeine increased parasympathetic reactivation after submaximal exercise (60–300 s post-exercise) but did not alter resting cardiac parasympathetic modulation or HRV threshold.
In obese adolescents on a calorie-restricted diet, an ephedrine+caffeine pill produced much larger weight, BMI, and body-fat loss over 20 weeks than placebo.
Survey of 4,271 US college students found that mixing energy drinks with alcohol was common and associated with higher heavy drinking and more alcohol-related harms.
In a double-blind crossover study, moderate caffeine during 38 h wakefulness reduced recovery-night total sleep time and N3 sleep and worsened sleep continuity and EEG slow-wave power.
In 84 patients, coadministration of ibuprofen plus caffeine did not reduce the risk or intensity of bleaching-induced tooth sensitivity compared with placebo.
In 58 adults, 12 weeks of catechin- and caffeine-containing green tea supplementation did not change gut microbiota composition or diversity nor body composition versus placebo.
Adding low-dose caffeine (60 mg) to patients' antidepressant regimens reduced depression scores, improved cognition, and normalized stress-hormone response.
Caffeine (200 mg) before sleep delayed sleep onset and reduced deep sleep, with stronger negative effects on daytime recovery sleep than nocturnal sleep.
Daily use of a shampoo containing caffeine plus DMG‑Na reduced hair shedding and improved hair growth measures versus placebo after 6 months.
In overweight adults, 8 weeks of caffeinated coffee increased adiponectin and IL‑6 while decaffeinated coffee lowered fetuin‑A; no change in glucose tolerance.
Neonatal caffeine therapy was not associated with differences in sleep duration or sleep-disordered breathing at school age.
Adding caffeine to ibuprofen sped pain relief onset and increased analgesic effect at 45–60 minutes after single-dose administration, with few adverse events.
Early caffeine in 59 preterm infants reduced ventilator needs, shortened respiratory support times, lowered VAP, and reduced post-extubation apnea.
Randomized double-blind right/left comparison: topical 10% caffeine applied thrice daily produced greater reduction in PASI scores than placebo after 8 weeks (small but statistically significant effect).
In healthy adults, increasing caffeine doses impaired insulin sensitivity and raised insulin, C-peptide, and glucose responses in a dose-dependent way.
In infants with bronchiolitis-associated apnea, a single IV caffeine dose did not shorten time to a 24-hour apnea-free period compared with placebo.
IV caffeine after spinal anesthesia reduced headache severity, fewer moderate/severe headaches, and reduced analgesic needs.
A single 400 mg dose of caffeine before graded CO₂ exposure reduced CO₂ retention and substantially lowered headache ratings compared with placebo.
Adding caffeine to paracetamol sped absorption (shorter Tmax), increased Cmax and Ka, and prolonged t1/2—effects greater in hepatic patients.
Early prophylactic caffeine in very preterm infants improved white-matter microstructure on MRI and reduced apnea/ventilation needs versus placebo.
In competitive male athletes, caffeine had no overall effect on strength/power, but 4 mg/kg caffeine reduced handgrip strength by ~12.8% in individuals with the CYP1A2 CC genotype.
In 28 trained young adults randomized to creatine, caffeine, creatine+caffeine, or placebo during 6 weeks training, creatine increased knee extensor thickness but caffeine produced no clear benefits.
Sixty abstinent coffee drinkers received decaf with 0 or 280 mg caffeine crossed with expectancy instructions; caffeine improved vigilance and psychomotor speed and expectancy altered subjective and some behavioral outcomes.
In 320 women with moderate-to-severe dysmenorrhoea, paracetamol (1 g) plus caffeine (130 mg) provided greater pain relief at 2 hours and better relief of cramping and backache than paracetamol alone, caffeine alone, or placebo.
In a double-blind crossover trial, caffeine taken before a mental stressor amplified cardiovascular/hemodynamic stress responses in both men and women.
In a 6-week double-blind randomized free-living trial, adding caffeine to a sugar-sweetened beverage increased ad libitum consumption compared with the non-caffeinated version.
In trained women habituated to caffeine, acute caffeine (3 and 6 mg/kg) increased 1RM strength (dose-response) and 6 mg/kg increased time under tension; no clear change in repetitions or power measures.
In 93 college-age moderate caffeine users, caffeine improved initial acquisition (accuracy and latency) on a proprioceptive force-discrimination learning task but did not improve performance beyond normal practice.
In a double-blind experiment (regular n=92, low/non-consumers n=89), acute stress slightly increased hallucination-like experiences; 100 mg caffeine produced a small time-dependent effect on threat-related recall bias.
In 51 patients with systolic heart failure, acute high-dose caffeine (total 500 mg) did not increase ventricular or supraventricular premature beats or exercise-derived arrhythmias compared with placebo.
In a multicenter RCT of 200 mg twice daily caffeine vs placebo in Parkinson’s disease (n=121), caffeine did not improve motor scores and had minor adverse effects on cognition and dyskinesia.
Preprocedural oral caffeine (5 mg/kg) increased PVC counts during isoproterenol washout, increased PVC count fluctuation, and shortened procedure and ablation times during catheter ablation.
Single 6 mg/kg caffeine dose before a triathlon slightly improved swim and overall completion times and increased postexercise cortisol and peak blood lactate.
A single 275 mg caffeine dose (or 150 mg caffeine + 125 mg theacrine) produced modest improvements in some reaction-time measures and trended to increase time-to-exhaustion versus placebo.
Two randomized crossover trials in men showed beverages containing green tea catechins and coffee chlorogenic acids (with matched caffeine) raised postprandial GLP-1, lowered GIP, and reduced post-meal blood glucose compared to placebo.
Acute ingestion of green or black tea produced larger short-term increases in clinic systolic and diastolic blood pressure than caffeine-matched water, but regular 7-day tea consumption did not significantly change 24-h ambulatory blood pressure.
Acute caffeine (6 mg/kg) improved countermovement jump performance and total repetitions in strength endurance tests regardless of habitual caffeine intake level.
During 40-h sleep deprivation, caffeine preserved simple response output but did not prevent many executive-function deficits on a random number task.
Male collegiate basketball players doing 6 weeks of plyometric training improved performance and physiology; ingesting caffeine 1 h before sessions (especially 6 mg/kg) produced slightly larger and more uniform adaptations than placebo.
In 120 preterm infants, higher-dose caffeine citrate reduced extubation failure and apnea frequency/duration but increased episodes of tachycardia.
In patients undergoing regadenoson-stress SPECT MPI, ingestion of caffeine (200–400 mg) 90 minutes before testing reduced the number and severity of detected reversible perfusion defects and altered BP/HR responses.
A brief school-based intervention modestly reduced electronic media use at night but did not change adolescents' caffeine consumption, sleep duration, or secondary outcomes.
On-demand 100 mg caffeine before intercourse increased ejaculation latency and sexual satisfaction versus placebo.
Caffeine gum prevented the rise in risky behaviour and reduced self-reported impulsivity during 75 hours of continuous sleep deprivation.
Overall caffeine intake was not linked to Parkinson progression, but among patients taking creatine higher caffeine intake was associated with faster disease progression.
Brief caffeine deprivation in habitual coffee drinkers caused decreased vigor, increased fatigue and sleepiness, and a modest drop in blood pressure; psychomotor performance unchanged.
In a double-blind crossover, 4 mg/kg caffeine increased perceived activation and pupil size and reduced variability of accommodative response, without altering accommodation accuracy.
Overweight subjects lost weight on a very low energy diet then during 3-month maintenance received a green tea–caffeine mixture or placebo; effects depended on habitual caffeine intake.
Paracetamol-caffeine reduced separator-related pain compared with placebo but did not improve overall oral-health-related quality of life.
Caffeine reduced sleepiness and improved motor performance (tapping and reaction times); improvements in mental alertness and cognition were mainly seen in medium-high consumers and were limited in frequent consumers.
After implant surgery, acetaminophen+caffeine produced less early postoperative swelling but more pain at 3–12 h compared with acetaminophen+codeine.
Across three experiments, caffeine-related attentional biases were observed, but deprivation increased coffee consumption and subjective drowsiness without altering attentional bias.
In early-phase psychosis patients (vs controls), acute caffeine shifted EEG microstate dynamics: it reduced class D and increased classes A and B parameters in patients but had little effect in controls.
In men, 3 mg/kg caffeine taken before treadmill running increased plasma dopamine and β-endorphin compared with control; serotonin rose with exercise regardless of caffeine.
Case-control analysis found associations between coffee (methylxanthine) intake and colon cancer risk in men that varied by intake level and tumor location.
Drinking 1 L/day of paper‑filtered coffee for 4 weeks raised fasting plasma homocysteine in healthy adults.
In novices, low-dose caffeine worsened simulator surgical performance and increased tremor; seniors showed mainly tremor changes without dexterity loss.
A moderate dose of caffeine (3 mg/kg) acutely improved bench-press velocity/power, muscle endurance, vertical jump height, and Wingate power in resistance-trained men, with no clear genotype differences.
Topical caffeine combined with interferon shortened healing time of recurrent herpetic lesions more than either agent alone; caffeine alone shortened healing time in many patients but had little effect on lesion spread.
In a crossover RCT of postmenopausal women with OAB, 400 mg/day caffeine for 7 days produced a small reduction in anxiety; depression, insomnia, and perceived stress showed no change.
Acute caffeine (~4 mg/kg) improved dynamic visual acuity (horizontal and random paths), shortened horizontal reaction time, and increased subjective activation in low-caffeine consumers.
In ~9,700 high-risk post‑MI patients, baseline caffeinated beverage intake was not associated with lower ticagrelor-related dyspnea but was associated with lower drug discontinuation for dyspnea and lower rates of MACE/MI in adjusted analyses.
Self-monitoring (including advice on caffeine) reduced urine loss and improved quality of life; participants also reduced caffeine intake.
In a double-blind crossover trial of 50 adults, 1 mg/kg caffeine transiently reduced laboratory breakfast intake by about 10% but did not change appetite ratings or free-living intake.
In 50 male smokers, an acute dose of caffeine increased subjective 'pleasant' effects and feeling 'high' but did not change cigarette consumption.
Extending caffeine citrate in moderately preterm infants did not shorten hospital stay or time to physiological maturity but led to earlier resolution of apnea.
A single 200 mg oral caffeine dose acutely reduced macular blood flow and vessel density measured by OCT-A at 1 hour.
During prolonged sleep deprivation, acute caffeine withdrawal worsened abstract reasoning/concept-formation performance (more errors) compared with placebo.
Single-blind randomized study found small improvements in basic attention and psychomotor speed after matcha products; no significant mood changes.
A nutrient-enriched breakfast bar (containing a low caffeine dose of 21.5 mg among many other ingredients) produced acute improvements in alertness, attention and several cognitive tasks versus placebo on Day 1 and Day 56.
In prostate cancer survivors, a single dose of caffeine (~6 mg/kg) increased exercise capacity (faster 400-m walk) and tended to increase grip strength, without changing perceived exertion.
In preterm infants at risk of recurrent apnea, early preventive caffeine citrate given within 8 h after birth was associated with larger decreases in IL-6 and IL-8 after therapy compared with later treatment; no significant difference in BPD incidence was demonstrated.
Acute consumption of large-volume caffeinated energy drinks (two 16-oz bottles; ~304–320 mg caffeine) in healthy adults increased QTc and raised brachial and central blood pressure compared with placebo.
Acute consumption of large-volume caffeinated energy drinks (two 16-oz bottles; ~304–320 mg caffeine) in healthy adults increased QTc and raised brachial and central blood pressure compared with placebo.
In a crossover trial, 300 mg caffeine given before resistance exercise delayed autonomic (HRV) recovery and slowed heart rate and blood pressure recovery after exercise.
In a crossover trial, 300 mg caffeine given before resistance exercise delayed autonomic (HRV) recovery and slowed heart rate and blood pressure recovery after exercise.
In very preterm infants, caffeine was linked to microstructural changes in white matter but not to changes in brain volumes.
In a randomized trial of 84 healthy men, daily consumption of a dark roast coffee for 4 weeks significantly reduced spontaneous DNA strand breaks in white blood cells compared with water (about 27% difference).
A multi-ingredient caffeine supplement did not change strength or cycling time-to-exhaustion in untrained men.
Caffeine modestly increased tear volume; genetic variants in ADORA2A and CYP1A2 influenced the size of the increase.
In sleep-deprived healthy men, higher caffeine doses (up to 8.6 mg/kg) increased adrenaline and produced dose-related improvements in alertness measures.
Higher maintenance caffeine dose after loading reduced re-intubation rate within 48 hours and apnea after ventilator weaning in very preterm infants.
At age 11, children randomized to neonatal caffeine therapy showed modest improvements in fine motor and visuomotor/visuospatial skills and no adverse effects on intelligence, attention, or behavior.
Multicentre randomized trial in adults comparing Indoprocaf (includes caffeine) vs sumatriptan: similar pain-free rates at 2 h, but Indoprocaf showed higher total pain-free rate at 5 h (including re-dosing).
In healthy young adults, 200 mg caffeine (alone or with cocoa flavanols) produced little-to-no acute benefits on temporal/spatial attention or working memory, aside from modest faster reaction times on some attention measures.
In young adults, combining an energy drink with alcohol reduced some subjective symptoms of intoxication but did not improve objective motor coordination, reaction time, or breath alcohol.
In obese adults after weight loss, rye bread enriched with green tea extract (providing ~123–158 mg caffeine/day) did not improve weight-loss maintenance but was associated with slightly better blood pressure control and a marginally smaller waist circumference.
Follow-up of very preterm infants (randomized to high vs standard loading caffeine dose) found no clear differences in cognitive, language, motor, or socioemotional outcomes at age five, despite higher early cerebellar hemorrhage in the high-dose group.
A cup of coffee (100 mg caffeine) improved and stabilized reaction time across 120 min regardless of recent sleep quality, but in those with poor sleep it increased commission errors at 90 min and only partially reduced omission errors.
In healthy young men, 300 mg caffeine taken before moderate aerobic exercise delayed parasympathetic heart-rate recovery and slowed blood pressure return to baseline, without changing HR, respiratory rate or oxygen saturation.
In preterm infants (≤32 weeks) on mechanical ventilation, an extra 5 mg/kg maintenance dose of caffeine 1 hour before weaning reduced reintubation and apnea episodes and lowered intraventricular hemorrhage incidence, with improved blood gas (higher pH, lower PaCO2) at 2 hours.
Single-dose combinations containing caffeine (with paracetamol and opium) provided superior analgesia to placebo and were non-inferior to tramadol after third-molar extraction, with faster onset and greater analgesic effect at 1 hour for the stronger formulation and acceptable safety.
At 5-year follow-up of a large neonatal RCT, early caffeine therapy for apnea of prematurity did not significantly change the combined outcome of death or survival with disability compared with placebo (no lasting significant benefit on survival without disability).
Caffeine (6 mg/kg) before a 15-km run increased plasma IL-10 and IL-6 responses after exercise versus placebo, but did not affect cytokines in blood mononuclear cells.
Caffeine-conditioned increases in drink pleasantness were expressed only when subjects were tested in the same caffeine-deprivation state as during conditioning.
Taking green tea extract capsules led to better absorption of tea flavanols and a small increase in blood antioxidant activity compared with drinking green or black tea.
Caffeine substantially reduced cerebral blood flow and middle cerebral artery velocity, implying narrowing of cerebral arterioles and the MCA.
In healthy adults undergoing prolonged wakefulness, acute caffeine altered IGF-1 responses depending on COMT genotype and reduced the drop in testosterone during sleep deprivation.
Adding 50 mg caffeine to paracetamol produced analgesia comparable to the tested comparator combination in patients with spinal osteoarthritis over one week.
In trained young adults, a single dose of caffeine before a maximal treadmill test reduced an oxidative stress marker and increased IL-6 after exercise, with no change in performance.
In 54 active men, creatine loading with or without added caffeine (or coffee) did not provide additional improvements in strength or sprint performance compared with placebo over 5 days.
A fixed-dose combination containing caffeine provided faster and greater short-term relief of episodic tension-type headache than nimesulide in compliant participants.
In 24 professional rugby players, acute caffeine increased exercise-associated testosterone modestly and, at high dose (800 mg), substantially raised cortisol, slightly lowering the testosterone:cortisol ratio.
Among ~296 migraine patients, the ergotamine+100 mg caffeine combination was less effective and had more gastrointestinal adverse effects than calcium carbasalate+metoclopramide.
In 104 overweight adults, green tea (containing 104 mg caffeine/day) did not significantly affect weight regain after weight loss overall, but habitual high caffeine consumers on green tea regained more weight.
Brief caffeine deprivation in habitual coffee drinkers caused decreased vigor, increased fatigue and sleepiness, and a modest drop in blood pressure; psychomotor performance unchanged.
Overweight subjects lost weight on a very low energy diet then during 3-month maintenance received a green tea–caffeine mixture or placebo; effects depended on habitual caffeine intake.
Paracetamol-caffeine reduced separator-related pain compared with placebo but did not improve overall oral-health-related quality of life.
Caffeine reduced sleepiness and improved motor performance (tapping and reaction times); improvements in mental alertness and cognition were mainly seen in medium-high consumers and were limited in frequent consumers.
Single 600 mg slow-release caffeine decreased calmness and prolonged sleep onset but did not change alertness the next day.
In 30 children (8–13 y), a single 80 mg oral caffeine dose increased physiological arousal (skin conductance) and altered EEG indices versus placebo.
A nonprescription combination including caffeine (with acetaminophen and aspirin) provided greater pain relief and functional improvement than placebo in OTC-appropriate migraine sufferers.
A nonprescription combination including caffeine (with acetaminophen and aspirin) provided greater pain relief and functional improvement than placebo in OTC-appropriate migraine sufferers.
A combination containing caffeine (AAC) provided faster and greater migraine pain relief and symptom improvement than placebo in both menstruation-associated and non-menstrual migraine.
In men, 3 mg/kg caffeine taken before treadmill running increased plasma dopamine and β-endorphin compared with control; serotonin rose with exercise regardless of caffeine.
Repeated caffeine gum (up to 200 mg every 2 hours) reduced vigilance lapses during an extended wake period and 200 mg preserved baseline performance overnight.
Caffeine (6.5 mg/kg) improved total repetitions in resistance training compared with placebo in active women; no additional benefit from combining with carbohydrate rinse.
Caffeine increased reflection time and games lost on time but did not improve overall chess performance under normal analysis of all games.
In novices, low-dose caffeine worsened simulator surgical performance and increased tremor; seniors showed mainly tremor changes without dexterity loss.
A moderate dose of caffeine (3 mg/kg) acutely improved bench-press velocity/power, muscle endurance, vertical jump height, and Wingate power in resistance-trained men, with no clear genotype differences.
In a crossover RCT of postmenopausal women with OAB, 400 mg/day caffeine for 7 days produced a small reduction in anxiety; depression, insomnia, and perceived stress showed no change.
Acute caffeine (~4 mg/kg) improved dynamic visual acuity (horizontal and random paths), shortened horizontal reaction time, and increased subjective activation in low-caffeine consumers.
In ~9,700 high-risk post‑MI patients, baseline caffeinated beverage intake was not associated with lower ticagrelor-related dyspnea but was associated with lower drug discontinuation for dyspnea and lower rates of MACE/MI in adjusted analyses.
In 24 treatment-resistant OCD patients, caffeine 300 mg/day augmentation produced symptom improvements comparable to dextroamphetamine over 5 weeks in this small double-blind trial.
In a randomized double-blind placebo-controlled trial (n=60) a citicoline-caffeine beverage improved sustained attention, reaction time, and working memory measures and increased P300 amplitudes on EEG vs placebo.
In a randomized double-blind placebo-controlled trial (n=60) a citicoline-caffeine beverage improved sustained attention, reaction time, and working memory measures and increased P300 amplitudes on EEG vs placebo.
In 379 participants, caffeine (100 mg then 150 mg) increased anxiety in genetically susceptible individuals (ADORA2A rs5751876 TT) especially among low habitual consumers; habitual consumption reduced anxiogenic response (tolerance) and no net alerting benefit was seen in some groups.
In 80 healthy volunteers, a 200 mg caffeine active control increased subjective alertness and affected cardiovascular measures.
In habitual coffee-drinking middle-aged women, caffeine (50–100 mg) reduced negative mood scores (notably anxiety/sadness); combining aspirin and caffeine did not increase positive mood or show clear abuse potential.
Self-monitoring (including advice on caffeine) reduced urine loss and improved quality of life; participants also reduced caffeine intake.
In 50 male smokers, an acute dose of caffeine increased subjective 'pleasant' effects and feeling 'high' but did not change cigarette consumption.
Extending caffeine citrate in moderately preterm infants did not shorten hospital stay or time to physiological maturity but led to earlier resolution of apnea.
In this prospective cohort of older women, higher baseline caffeine intake was associated with lower incidence of probable dementia and cognitive impairment over follow-up.
A nutrient-enriched breakfast bar (containing a low caffeine dose of 21.5 mg among many other ingredients) produced acute improvements in alertness, attention and several cognitive tasks versus placebo on Day 1 and Day 56.
In prostate cancer survivors, a single dose of caffeine (~6 mg/kg) increased exercise capacity (faster 400-m walk) and tended to increase grip strength, without changing perceived exertion.
In preterm infants at risk of recurrent apnea, early preventive caffeine citrate given within 8 h after birth was associated with larger decreases in IL-6 and IL-8 after therapy compared with later treatment; no significant difference in BPD incidence was demonstrated.
In a single-blind crossover, breakfast including espresso plus either carbohydrate or protein improved mood, physiological state and short-term verbal memory; authors attribute effects to both croissants and caffeine.
In very preterm infants, caffeine was linked to microstructural changes in white matter but not to changes in brain volumes.
Acute caffeine in elderly reduced global brain perfusion but enhanced working‑memory related fMRI activation and increased functional connectivity in task networks.
Caffeine (6 mg/kg) increased resistance-exercise repetitions in CYP1A2 AA homozygotes but not in C-allele carriers.
In sleep-deprived healthy men, higher caffeine doses (up to 8.6 mg/kg) increased adrenaline and produced dose-related improvements in alertness measures.
Higher maintenance caffeine dose after loading reduced re-intubation rate within 48 hours and apnea after ventilator weaning in very preterm infants.
At age 11, children randomized to neonatal caffeine therapy showed modest improvements in fine motor and visuomotor/visuospatial skills and no adverse effects on intelligence, attention, or behavior.
Multicentre randomized trial in adults comparing Indoprocaf (includes caffeine) vs sumatriptan: similar pain-free rates at 2 h, but Indoprocaf showed higher total pain-free rate at 5 h (including re-dosing).
In healthy young adults, 200 mg caffeine (alone or with cocoa flavanols) produced little-to-no acute benefits on temporal/spatial attention or working memory, aside from modest faster reaction times on some attention measures.
In young adults, combining an energy drink with alcohol reduced some subjective symptoms of intoxication but did not improve objective motor coordination, reaction time, or breath alcohol.
A cup of coffee (100 mg caffeine) improved and stabilized reaction time across 120 min regardless of recent sleep quality, but in those with poor sleep it increased commission errors at 90 min and only partially reduced omission errors.
In preterm infants (≤32 weeks) on mechanical ventilation, an extra 5 mg/kg maintenance dose of caffeine 1 hour before weaning reduced reintubation and apnea episodes and lowered intraventricular hemorrhage incidence, with improved blood gas (higher pH, lower PaCO2) at 2 hours.
Single-dose combinations containing caffeine (with paracetamol and opium) provided superior analgesia to placebo and were non-inferior to tramadol after third-molar extraction, with faster onset and greater analgesic effect at 1 hour for the stronger formulation and acceptable safety.
Taking green tea extract capsules led to better absorption of tea flavanols and a small increase in blood antioxidant activity compared with drinking green or black tea.
Caffeine substantially reduced cerebral blood flow and middle cerebral artery velocity, implying narrowing of cerebral arterioles and the MCA.
In healthy adults undergoing prolonged wakefulness, acute caffeine altered IGF-1 responses depending on COMT genotype and reduced the drop in testosterone during sleep deprivation.
In an 8-week randomized trial in overweight habitual coffee drinkers, caffeinated and decaffeinated coffee produced some short-term (week 4) changes in sex hormones that were not sustained at week 8.
Adding 50 mg caffeine to paracetamol produced analgesia comparable to the tested comparator combination in patients with spinal osteoarthritis over one week.
A fixed-dose combination containing caffeine provided faster and greater short-term relief of episodic tension-type headache than nimesulide in compliant participants.
Combination treatment including ephedrine plus caffeine reduced body fat and altered lipid-related gene expression; caffeine was given as part of a multi-drug regimen so individual caffeine effects are not isolated.
A combined caffeine+ephedra supplement raised resting metabolic rate and produced greater weight and fat loss than placebo over 12 weeks.
In 24 professional rugby players, acute caffeine increased exercise-associated testosterone modestly and, at high dose (800 mg), substantially raised cortisol, slightly lowering the testosterone:cortisol ratio.
Among ~296 migraine patients, the ergotamine+100 mg caffeine combination was less effective and had more gastrointestinal adverse effects than calcium carbasalate+metoclopramide.
In 104 overweight adults, green tea (containing 104 mg caffeine/day) did not significantly affect weight regain after weight loss overall, but habitual high caffeine consumers on green tea regained more weight.
After eastbound travel across seven time zones, slow‑release caffeine (300 mg) prevented the post-travel decline in dominant-hand static strength seen with placebo, while dynamic measures were unchanged.
In a large multicenter RCT, the acetaminophen+aspirin+caffeine combination provided faster and greater pain relief than ibuprofen and placebo in patients with severe migraine.
In a large multicenter RCT, the acetaminophen+aspirin+caffeine combination provided faster and greater pain relief than ibuprofen and placebo in patients with severe migraine.
Regular consumption of black tea (3 cups/day) reduced nighttime blood-pressure variability by about 10% compared with a flavonoid-free caffeine-matched control; effect appears independent of caffeine.
In healthy young males, 200 mg caffeine improved sustained attention (shorter reaction time) but showed no robust effects on most other cognitive domains or subjective fatigue.
In 100 healthy drivers, a single 200 mg caffeine dose improved some executive/cognitive test performance and shortened brake reaction time versus placebo.
Across three experiments, caffeine-related attentional biases were observed, but deprivation increased coffee consumption and subjective drowsiness without altering attentional bias.
In 28 participants (14 habituated, 14 non-habituated), 5 mg/kg caffeine increased end-exercise esophageal temperature and attenuated skin blood flow responses in caffeine-habituated individuals but had no effect in non-habituated participants or on sweating.
In 30 healthy physically active males, 5 mg/kg/day caffeine over 4 days did not change resting or activity-related energy expenditure but reduced total sleep time.
In preterm infants with primary apnea, a higher maintenance dose of caffeine citrate improved apnea control and ventilator weaning success without increasing measured side effects.
In early-phase psychosis patients (vs controls), acute caffeine shifted EEG microstate dynamics: it reduced class D and increased classes A and B parameters in patients but had little effect in controls.
Caffeine counteracted some alcohol-induced slowing on psychomotor speed and partially reduced alcohol-related errors on specific tasks.
200 mg oral caffeine before an OGTT shifted the glucose curve rightward with higher glucose at 2–4 hours without changing insulin levels.
Case-control analysis found associations between coffee (methylxanthine) intake and colon cancer risk in men that varied by intake level and tumor location.
A 250 mg caffeine drink increased pupil size and amplitude of accommodation over 90 minutes in young adults.
Caffeine increased reflection time and games lost on time but did not improve overall chess performance under normal analysis of all games.
In healthy elderly adults, 6 mg/kg caffeine increased plasma epinephrine, free fatty acids, and lactate (percent increases consistent at rest, 5 min, and exhaustion), and increased insulin-resistance measures.
In preterm infants (26–32 wk) on caffeine therapy for apnea, stopping after 7 apnea-free days did not increase recurrence vs continuing until 34 wk PMA, and stopping earlier reduced cumulative therapy duration.
In sleep-deprived healthy adults, caffeine (600 mg) did not meaningfully restore risk-taking propensity to rested baseline, whereas dextroamphetamine did.
Caffeine increases physiological arousal (higher skin conductance) and reduces EEG alpha; these effects add to those of opening the eyes.
In a three-arm randomized crossover trial (n=21), different coffee intake patterns produced distinct urinary metabolomic changes implicating pathways (e.g., phenylalanine/tyrosine, energy metabolism, steroid and arginine biosynthesis), suggesting coffee (which contains caffeine) alters metabolic profiles.
In 42 PDPH patients, gabapentin reduced pain, nausea, and vomiting more than ergotamine/caffeine (Cafergot); Cafergot was less effective than gabapentin in this setting.
A single 200 mg oral caffeine dose acutely reduced macular blood flow and vessel density measured by OCT-A at 1 hour.
Single-blind randomized study found small improvements in basic attention and psychomotor speed after matcha products; no significant mood changes.
Oral coffee with increasing caffeine doses raised measurable caffeine levels in the lens capsule/lens epithelial cells in cataract patients in a dose-dependent way.
In very preterm infants, caffeine was linked to microstructural changes in white matter but not to changes in brain volumes.
In resistance-trained men, a caffeine-containing supplement increased bench-press 1RM but did not affect leg strength, endurance, or Wingate power.
A multi‑component product that includes caffeine improved common‑cold symptom scores more than controls, though caffeine was not tested alone.
Acute caffeine in elderly reduced global brain perfusion but enhanced working‑memory related fMRI activation and increased functional connectivity in task networks.
Caffeine modestly increased tear volume; genetic variants in ADORA2A and CYP1A2 influenced the size of the increase.
Caffeine increased skin conductance (arousal) in children, but dose-response differed between AD/HD and control groups.
Follow-up of very preterm infants (randomized to high vs standard loading caffeine dose) found no clear differences in cognitive, language, motor, or socioemotional outcomes at age five, despite higher early cerebellar hemorrhage in the high-dose group.
Paracetamol 1000 mg + caffeine 130 mg relieved migraine pain as well as sumatriptan 50 mg with similar overall tolerability; fatigue was slightly more common with sumatriptan.
Caffeine (6 mg/kg) before a 15-km run increased plasma IL-10 and IL-6 responses after exercise versus placebo, but did not affect cytokines in blood mononuclear cells.
Caffeine-conditioned increases in drink pleasantness were expressed only when subjects were tested in the same caffeine-deprivation state as during conditioning.
In a large prospective cohort of women, higher caffeine intake was not associated with an increased risk of developing atrial fibrillation.
In an 8-week randomized trial in overweight habitual coffee drinkers, caffeinated and decaffeinated coffee produced some short-term (week 4) changes in sex hormones that were not sustained at week 8.
In habitual caffeine consumers, the combination of Alpinia galanga extract with caffeine reduced mean response time (improved sustained attention) at 3 hours compared with placebo.
In habitual male caffeine users, single-dose caffeine (200 or 400 mg) did not change salivary alpha-amylase, cortisol, or cardiovascular measures during a non-stressful task.
In 40 habitual coffee consumers in a randomized crossover design, single servings of coffee (160 mg caffeine) increased salivary alpha-amylase and transiently increased salivary gastrin and blood pressure, but did not change salivary cortisol or self-reported GI symptoms.
Acute ingestion of various energy drinks (contain caffeine plus blends) produced group-specific increases in blood pressure, heart rate, cortisol, and mixed effects on anxiety and working memory.
Caffeine-associated cues and information about caffeine content modulated physiological and subjective arousal; conditioned and expectancy effects both contributed.
A single 300 mg oral caffeine dose acutely increased inner-retinal electrophysiological responses at high/medium contrast and increased subjective alertness in young adults.
Caffeine, naps, and especially their combination improved alertness and vigilance in laboratory and field night-shift settings.
In 40 women, 200 mg caffeine altered threat‑selective attention in a manner that depended on baseline EEG theta/beta ratio and trait anxiety (no uniform directional effect).
A fixed-dose combination containing caffeine provided faster and greater short-term relief of episodic tension-type headache than nimesulide in compliant participants.
Matcha (contains caffeine and theanine) modestly lowered anxiety and morning salivary stress marker in students, but baseline group differences and modest effects limit certainty.
Combination treatment including ephedrine plus caffeine reduced body fat and altered lipid-related gene expression; caffeine was given as part of a multi-drug regimen so individual caffeine effects are not isolated.
In 24 professional rugby players, acute caffeine increased exercise-associated testosterone modestly and, at high dose (800 mg), substantially raised cortisol, slightly lowering the testosterone:cortisol ratio.
Among ~296 migraine patients, the ergotamine+100 mg caffeine combination was less effective and had more gastrointestinal adverse effects than calcium carbasalate+metoclopramide.
Diclofenac softgel plus 100 mg caffeine provided greater headache relief at 60 minutes versus placebo in migraineurs; diclofenac alone showed non-significant differences (study underpowered).
After eastbound travel across seven time zones, slow‑release caffeine (300 mg) prevented the post-travel decline in dominant-hand static strength seen with placebo, while dynamic measures were unchanged.
In a randomized, double-blind crossover study of healthy young adults, consumption of Red Bull (contains caffeine) improved working and episodic memory accuracy and speed compared with sugar-free and placebo drinks.
Randomized comparison of caffeine versus aminophylline for apnea of prematurity showed trends toward lower risks of cognitive, motor, and language impairments with caffeine but differences were not statistically significant.
A 250-ml Red Bull (80 mg caffeine) consumed during a short break improved driving stability and reduced sleepiness for about 2 hours compared with placebo or no break.
Regular consumption of black tea (3 cups/day) reduced nighttime blood-pressure variability by about 10% compared with a flavonoid-free caffeine-matched control; effect appears independent of caffeine.
In 30 children (8–13 y), a single 80 mg oral caffeine dose increased physiological arousal (skin conductance) and altered EEG indices versus placebo.
In preterm infants with primary apnea, a higher maintenance dose of caffeine citrate improved apnea control and ventilator weaning success without increasing measured side effects.
In men, 3 mg/kg caffeine taken before treadmill running increased plasma dopamine and β-endorphin compared with control; serotonin rose with exercise regardless of caffeine.
200 mg oral caffeine before an OGTT shifted the glucose curve rightward with higher glucose at 2–4 hours without changing insulin levels.
Caffeine increased reflection time and games lost on time but did not improve overall chess performance under normal analysis of all games.
A 480 mg oral caffeine challenge induced panic attacks in a majority of panic disorder (60.7%) and performance social anxiety disorder (52.6%) patients, in fewer GSAD patients (16%), and in no controls.
Acute caffeine (~4 mg/kg) improved dynamic visual acuity (horizontal and random paths), shortened horizontal reaction time, and increased subjective activation in low-caffeine consumers.
In preterm infants (26–32 wk) on caffeine therapy for apnea, stopping after 7 apnea-free days did not increase recurrence vs continuing until 34 wk PMA, and stopping earlier reduced cumulative therapy duration.
In sleep-deprived healthy adults, caffeine (600 mg) did not meaningfully restore risk-taking propensity to rested baseline, whereas dextroamphetamine did.
In ~9,700 high-risk post‑MI patients, baseline caffeinated beverage intake was not associated with lower ticagrelor-related dyspnea but was associated with lower drug discontinuation for dyspnea and lower rates of MACE/MI in adjusted analyses.
In 24 treatment-resistant OCD patients, caffeine 300 mg/day augmentation produced symptom improvements comparable to dextroamphetamine over 5 weeks in this small double-blind trial.
Over 8 weeks, the caffeine arm showed no statistically significant changes in vital signs or routine lab safety measures compared with other groups.
In 42 PDPH patients, gabapentin reduced pain, nausea, and vomiting more than ergotamine/caffeine (Cafergot); Cafergot was less effective than gabapentin in this setting.
Thinking/talking about caffeine made students report stronger cravings for caffeine.
In 50 male smokers, an acute dose of caffeine increased subjective 'pleasant' effects and feeling 'high' but did not change cigarette consumption.
In this prospective cohort of older women, higher baseline caffeine intake was associated with lower incidence of probable dementia and cognitive impairment over follow-up.
Oral coffee with increasing caffeine doses raised measurable caffeine levels in the lens capsule/lens epithelial cells in cataract patients in a dose-dependent way.
In prostate cancer survivors, a single dose of caffeine (~6 mg/kg) increased exercise capacity (faster 400-m walk) and tended to increase grip strength, without changing perceived exertion.
In preterm infants at risk of recurrent apnea, early preventive caffeine citrate given within 8 h after birth was associated with larger decreases in IL-6 and IL-8 after therapy compared with later treatment; no significant difference in BPD incidence was demonstrated.
In young adults, a single dose of 97 mg L-theanine combined with 40 mg caffeine improved task-switching accuracy and increased self-reported alertness while reducing tiredness.
In young adults, a single dose of 97 mg L-theanine combined with 40 mg caffeine improved task-switching accuracy and increased self-reported alertness while reducing tiredness.
In a single-blind crossover, breakfast including espresso plus either carbohydrate or protein improved mood, physiological state and short-term verbal memory; authors attribute effects to both croissants and caffeine.
In resistance-trained men, a caffeine-containing supplement increased bench-press 1RM but did not affect leg strength, endurance, or Wingate power.
Acute caffeine in elderly reduced global brain perfusion but enhanced working‑memory related fMRI activation and increased functional connectivity in task networks.
Caffeine increased skin conductance (arousal) in children, but dose-response differed between AD/HD and control groups.
In sleep-deprived healthy men, higher caffeine doses (up to 8.6 mg/kg) increased adrenaline and produced dose-related improvements in alertness measures.
Higher maintenance caffeine dose after loading reduced re-intubation rate within 48 hours and apnea after ventilator weaning in very preterm infants.
At age 11, children randomized to neonatal caffeine therapy showed modest improvements in fine motor and visuomotor/visuospatial skills and no adverse effects on intelligence, attention, or behavior.
Multicentre randomized trial in adults comparing Indoprocaf (includes caffeine) vs sumatriptan: similar pain-free rates at 2 h, but Indoprocaf showed higher total pain-free rate at 5 h (including re-dosing).
In healthy young adults, 200 mg caffeine (alone or with cocoa flavanols) produced little-to-no acute benefits on temporal/spatial attention or working memory, aside from modest faster reaction times on some attention measures.
In young adults, combining an energy drink with alcohol reduced some subjective symptoms of intoxication but did not improve objective motor coordination, reaction time, or breath alcohol.
Drinking three cups/day of lightly roasted (higher polyphenols and caffeine) or regular coffee for 12 weeks reduced body fat percentage and increased muscle mass in overweight/obese adults; lightly roasted coffee produced a slightly greater fat percentage reduction.
Paracetamol 1000 mg + caffeine 130 mg relieved migraine pain as well as sumatriptan 50 mg with similar overall tolerability; fatigue was slightly more common with sumatriptan.
A cup of coffee (100 mg caffeine) improved and stabilized reaction time across 120 min regardless of recent sleep quality, but in those with poor sleep it increased commission errors at 90 min and only partially reduced omission errors.
A combination containing caffeine (AAC) provided faster and greater migraine pain relief and symptom improvement than placebo in both menstruation-associated and non-menstrual migraine.
In an 8-week randomized trial in overweight habitual coffee drinkers, caffeinated and decaffeinated coffee produced some short-term (week 4) changes in sex hormones that were not sustained at week 8.
In preterm infants, caffeine citrate was associated with higher global cerebral blood flow than aminophylline two hours after IV administration.
In habitual male caffeine users, single-dose caffeine (200 or 400 mg) did not change salivary alpha-amylase, cortisol, or cardiovascular measures during a non-stressful task.
Caffeine-associated cues and information about caffeine content modulated physiological and subjective arousal; conditioned and expectancy effects both contributed.
In trained young adults, a single dose of caffeine before a maximal treadmill test reduced an oxidative stress marker and increased IL-6 after exercise, with no change in performance.
A single 400 mg dose of caffeine before graded CO₂ exposure reduced CO₂ retention and substantially lowered headache ratings compared with placebo.
Matcha (contains caffeine and theanine) modestly lowered anxiety and morning salivary stress marker in students, but baseline group differences and modest effects limit certainty.
In healthy male drivers, caffeine (2×200 mg) taken before and during night driving reduced lane departures and weaving compared with placebo, improving driving performance.
In a randomized, double-blind crossover study of healthy young adults, consumption of Red Bull (contains caffeine) improved working and episodic memory accuracy and speed compared with sugar-free and placebo drinks.
In 87 very low‑birthweight preterm infants, initiating caffeine in the first 24 hours was associated with lower mesenteric tissue oxygen saturation and a higher incidence of necrotizing enterocolitis compared with starting at 72 hours.
In this randomized crossover PK/safety study, consuming anagrelide with a standardized breakfast including two cups of coffee (caffeine) delayed tmax and was associated with larger early heart-rate increases and a numerically higher frequency of palpitations versus fasted dosing.
Randomized comparison of caffeine versus aminophylline for apnea of prematurity showed trends toward lower risks of cognitive, motor, and language impairments with caffeine but differences were not statistically significant.
Post-hoc subgroup analysis found the ASA+paracetamol+caffeine combination provided faster and greater pain relief than placebo in patients with severe headache.
A 250-ml Red Bull (80 mg caffeine) consumed during a short break improved driving stability and reduced sleepiness for about 2 hours compared with placebo or no break.
Across three experiments, caffeine-related attentional biases were observed, but deprivation increased coffee consumption and subjective drowsiness without altering attentional bias.
In 28 participants (14 habituated, 14 non-habituated), 5 mg/kg caffeine increased end-exercise esophageal temperature and attenuated skin blood flow responses in caffeine-habituated individuals but had no effect in non-habituated participants or on sweating.
In 30 healthy physically active males, 5 mg/kg/day caffeine over 4 days did not change resting or activity-related energy expenditure but reduced total sleep time.
In early-phase psychosis patients (vs controls), acute caffeine shifted EEG microstate dynamics: it reduced class D and increased classes A and B parameters in patients but had little effect in controls.
Caffeine counteracted some alcohol-induced slowing on psychomotor speed and partially reduced alcohol-related errors on specific tasks.
Case-control analysis found associations between coffee (methylxanthine) intake and colon cancer risk in men that varied by intake level and tumor location.
Caffeine increased time to exhaustion and oxygen deficit in a supramaximal anaerobic test and raised metabolic markers.
In elite male endurance athletes, 4.5 mg·kg-1 caffeine increased endurance performance and several physiological markers during incremental running to exhaustion.
In novices, low-dose caffeine worsened simulator surgical performance and increased tremor; seniors showed mainly tremor changes without dexterity loss.
A moderate dose of caffeine (3 mg/kg) acutely improved bench-press velocity/power, muscle endurance, vertical jump height, and Wingate power in resistance-trained men, with no clear genotype differences.
Topical caffeine combined with interferon shortened healing time of recurrent herpetic lesions more than either agent alone; caffeine alone shortened healing time in many patients but had little effect on lesion spread.
In a crossover RCT of postmenopausal women with OAB, 400 mg/day caffeine for 7 days produced a small reduction in anxiety; depression, insomnia, and perceived stress showed no change.
In a three-arm randomized crossover trial (n=21), different coffee intake patterns produced distinct urinary metabolomic changes implicating pathways (e.g., phenylalanine/tyrosine, energy metabolism, steroid and arginine biosynthesis), suggesting coffee (which contains caffeine) alters metabolic profiles.
Self-monitoring (including advice on caffeine) reduced urine loss and improved quality of life; participants also reduced caffeine intake.
In a double-blind crossover trial of 50 adults, 1 mg/kg caffeine transiently reduced laboratory breakfast intake by about 10% but did not change appetite ratings or free-living intake.
Extending caffeine citrate in moderately preterm infants did not shorten hospital stay or time to physiological maturity but led to earlier resolution of apnea.
A single 200 mg oral caffeine dose acutely reduced macular blood flow and vessel density measured by OCT-A at 1 hour.
Single-blind randomized study found small improvements in basic attention and psychomotor speed after matcha products; no significant mood changes.
In very preterm infants, caffeine was linked to microstructural changes in white matter but not to changes in brain volumes.
In resistance-trained men, a caffeine-containing supplement increased bench-press 1RM but did not affect leg strength, endurance, or Wingate power.
A multi-ingredient caffeine supplement did not change strength or cycling time-to-exhaustion in untrained men.
Caffeine modestly increased tear volume; genetic variants in ADORA2A and CYP1A2 influenced the size of the increase.
Follow-up of very preterm infants (randomized to high vs standard loading caffeine dose) found no clear differences in cognitive, language, motor, or socioemotional outcomes at age five, despite higher early cerebellar hemorrhage in the high-dose group.
Paracetamol 1000 mg + caffeine 130 mg relieved migraine pain as well as sumatriptan 50 mg with similar overall tolerability; fatigue was slightly more common with sumatriptan.
In preterm infants (≤32 weeks) on mechanical ventilation, an extra 5 mg/kg maintenance dose of caffeine 1 hour before weaning reduced reintubation and apnea episodes and lowered intraventricular hemorrhage incidence, with improved blood gas (higher pH, lower PaCO2) at 2 hours.
Single-dose combinations containing caffeine (with paracetamol and opium) provided superior analgesia to placebo and were non-inferior to tramadol after third-molar extraction, with faster onset and greater analgesic effect at 1 hour for the stronger formulation and acceptable safety.
At 5-year follow-up of a large neonatal RCT, early caffeine therapy for apnea of prematurity did not significantly change the combined outcome of death or survival with disability compared with placebo (no lasting significant benefit on survival without disability).
After 26 h wakefulness, caffeine did not worsen recovery or next-night sleep compared with placebo.
After 26 h wakefulness, caffeine did not worsen recovery or next-night sleep compared with placebo.
Caffeine (6 mg/kg) before a 15-km run increased plasma IL-10 and IL-6 responses after exercise versus placebo, but did not affect cytokines in blood mononuclear cells.
Caffeine-conditioned increases in drink pleasantness were expressed only when subjects were tested in the same caffeine-deprivation state as during conditioning.
Stopping coffee in iron-deficient Guatemalan toddlers increased night and total sleep but did not change cognitive test scores.
A 6-month randomized trial of an herbal ephedra/caffeine product produced greater weight loss than placebo and increased some GI and sleep-related side effects.
In habitual male caffeine users, single-dose caffeine (200 or 400 mg) did not change salivary alpha-amylase, cortisol, or cardiovascular measures during a non-stressful task.
Caffeine-associated cues and information about caffeine content modulated physiological and subjective arousal; conditioned and expectancy effects both contributed.
A single 300 mg oral caffeine dose acutely increased inner-retinal electrophysiological responses at high/medium contrast and increased subjective alertness in young adults.
In trained young adults, a single dose of caffeine before a maximal treadmill test reduced an oxidative stress marker and increased IL-6 after exercise, with no change in performance.
A single 400 mg dose of caffeine before graded CO₂ exposure reduced CO₂ retention and substantially lowered headache ratings compared with placebo.
Among ~296 migraine patients, the ergotamine+100 mg caffeine combination was less effective and had more gastrointestinal adverse effects than calcium carbasalate+metoclopramide.
In healthy male drivers, caffeine (2×200 mg) taken before and during night driving reduced lane departures and weaving compared with placebo, improving driving performance.
In 87 very low‑birthweight preterm infants, initiating caffeine in the first 24 hours was associated with lower mesenteric tissue oxygen saturation and a higher incidence of necrotizing enterocolitis compared with starting at 72 hours.
In this randomized crossover PK/safety study, consuming anagrelide with a standardized breakfast including two cups of coffee (caffeine) delayed tmax and was associated with larger early heart-rate increases and a numerically higher frequency of palpitations versus fasted dosing.
Post-hoc subgroup analysis found the ASA+paracetamol+caffeine combination provided faster and greater pain relief than placebo in patients with severe headache.
A multi-ingredient product (including caffeine and ephedrine) produced modest additional weight loss (~1.5 kg) and greater reductions in BMI and waist circumference versus placebo over 12 weeks; no BP or pulse increases were observed.
In healthy male drivers, caffeine (2×200 mg) taken before and during night driving reduced lane departures and weaving compared with placebo, improving driving performance.
In this randomized crossover PK/safety study, consuming anagrelide with a standardized breakfast including two cups of coffee (caffeine) delayed tmax and was associated with larger early heart-rate increases and a numerically higher frequency of palpitations versus fasted dosing.
Regular consumption of black tea (3 cups/day) reduced nighttime blood-pressure variability by about 10% compared with a flavonoid-free caffeine-matched control; effect appears independent of caffeine.
In overweight/obese adults, a higher-dose coffee (6 mg/kg caffeine) reduced energy intake at the next meal and over the day versus lower-dose or water; appetite ratings were unchanged.
In overweight/obese adults, a higher-dose coffee (6 mg/kg caffeine) reduced energy intake at the next meal and over the day versus lower-dose or water; appetite ratings were unchanged.
In overweight/obese adults, a higher-dose coffee (6 mg/kg caffeine) reduced energy intake at the next meal and over the day versus lower-dose or water; appetite ratings were unchanged.
Across multiple attacks, the indomethacin+prochlorperazine+caffeine combination produced a higher percentage of pain-free attacks at 2 hours than sumatriptan and better sustained pain-free responses.
Across multiple attacks, the indomethacin+prochlorperazine+caffeine combination produced a higher percentage of pain-free attacks at 2 hours than sumatriptan and better sustained pain-free responses.
Across multiple attacks, the indomethacin+prochlorperazine+caffeine combination produced a higher percentage of pain-free attacks at 2 hours than sumatriptan and better sustained pain-free responses.
A single 500 mg caffeine dose in habitual coffee drinkers raised ambulatory blood pressure by ~4/3 mmHg, lowered heart rate by ~2 bpm, and increased urinary free epinephrine by ~32%, amplifying stress-related cardiovascular responses.
A single 500 mg caffeine dose in habitual coffee drinkers raised ambulatory blood pressure by ~4/3 mmHg, lowered heart rate by ~2 bpm, and increased urinary free epinephrine by ~32%, amplifying stress-related cardiovascular responses.
In preterm infants treated for apnoea, caffeine did not differ from theophylline in erythropoietin levels by week 7; reticulocyte counts were higher with caffeine.
In preterm infants treated for apnoea, caffeine did not differ from theophylline in erythropoietin levels by week 7; reticulocyte counts were higher with caffeine.
In preterm infants treated for apnoea, caffeine did not differ from theophylline in erythropoietin levels by week 7; reticulocyte counts were higher with caffeine.
In this pilot RCT of extremely preterm infants, early intravenous caffeine (≤2 h age) improved blood pressure and systemic blood flow measures but did not change need for intubation by 12 h.
In this pilot RCT of extremely preterm infants, early intravenous caffeine (≤2 h age) improved blood pressure and systemic blood flow measures but did not change need for intubation by 12 h.
In this pilot RCT of extremely preterm infants, early intravenous caffeine (≤2 h age) improved blood pressure and systemic blood flow measures but did not change need for intubation by 12 h.
In a 33-subject crossover trial, coffee with caffeine altered postprandial gut- and pancreas-derived proglucagon peptides compared with water.
In a 33-subject crossover trial, coffee with caffeine altered postprandial gut- and pancreas-derived proglucagon peptides compared with water.
In 27 participants across three groups, slow-release caffeine reduced daytime sleepiness after an eastbound 7-time-zone flight but tended to affect sleep quality.
In healthy adults, 50 mg caffeine reduced errors on a 2-hour sustained attention task and reduced alpha-band EEG activity (especially in the first hour); theanine also reduced errors but did not change alpha activity.
In healthy adults, 50 mg caffeine reduced errors on a 2-hour sustained attention task and reduced alpha-band EEG activity (especially in the first hour); theanine also reduced errors but did not change alpha activity.
In healthy adults, 50 mg caffeine reduced errors on a 2-hour sustained attention task and reduced alpha-band EEG activity (especially in the first hour); theanine also reduced errors but did not change alpha activity.
Follow-up of a neonatal RCT found no significant difference in combined functional impairment at age 11, but neonatal caffeine therapy was associated with lower rates of motor impairment versus placebo.
Follow-up of a neonatal RCT found no significant difference in combined functional impairment at age 11, but neonatal caffeine therapy was associated with lower rates of motor impairment versus placebo.
Follow-up of a neonatal RCT found no significant difference in combined functional impairment at age 11, but neonatal caffeine therapy was associated with lower rates of motor impairment versus placebo.
In human endotoxemia, circulating adenosine rose; pretreatment with intravenous caffeine (4 mg/kg) did not alter the inflammatory cytokine response or markers of (subclinical) organ injury compared with placebo.
In human endotoxemia, circulating adenosine rose; pretreatment with intravenous caffeine (4 mg/kg) did not alter the inflammatory cytokine response or markers of (subclinical) organ injury compared with placebo.
In human endotoxemia, circulating adenosine rose; pretreatment with intravenous caffeine (4 mg/kg) did not alter the inflammatory cytokine response or markers of (subclinical) organ injury compared with placebo.
In adults ≥70 years, a single 6 mg/kg dose of caffeine increased cycling endurance time versus placebo; other measures showed no consistent benefit.
In adults ≥70 years, a single 6 mg/kg dose of caffeine increased cycling endurance time versus placebo; other measures showed no consistent benefit.
In adults ≥70 years, a single 6 mg/kg dose of caffeine increased cycling endurance time versus placebo; other measures showed no consistent benefit.
In elite male endurance athletes, 4.5 mg·kg-1 caffeine increased endurance performance and several physiological markers during incremental running to exhaustion.
In healthy volunteers, caffeine induced a marked decrease in cerebral blood flow measured by ASL, but measured magnitude differed by vendor/sequence affecting multicenter reproducibility.
In sleep-deprived young men, 200 mg caffeine attenuated performance impairments and EEG changes (frontal theta gradient) observed with prolonged waking, especially in caffeine-sensitive individuals.
In sleep-deprived young men, 200 mg caffeine attenuated performance impairments and EEG changes (frontal theta gradient) observed with prolonged waking, especially in caffeine-sensitive individuals.
In sleep-deprived young men, 200 mg caffeine attenuated performance impairments and EEG changes (frontal theta gradient) observed with prolonged waking, especially in caffeine-sensitive individuals.
In a large randomized double-blind trial, the fixed combination acetylsalicylic acid+paracetamol+caffeine showed superior efficacy for treated headaches compared with formulations lacking caffeine, single agents, and placebo.
In adolescent male athletes, 6 mg/kg caffeine increased endurance performance (Yo-Yo IR1 distance) and VO2max in ACE II and DI genotype carriers but not in DD carriers; heart rate and perceived exertion also rose in I-allele carriers.
In adolescent male athletes, 6 mg/kg caffeine increased endurance performance (Yo-Yo IR1 distance) and VO2max in ACE II and DI genotype carriers but not in DD carriers; heart rate and perceived exertion also rose in I-allele carriers.
In borderline hypertensive men, a dietary dose of caffeine (3.3 mg/kg) combined with a psychomotor stressor produced larger blood pressure increases than in normotensive controls.
In a small randomized double-blind trial using caffeine as the active comparator, both placebo and caffeine reduced self-reported drowsiness and increased prefrontal blood flow; subjects with L/L 5-HTTLPR genotype showed larger placebo responses.
In a small randomized double-blind trial using caffeine as the active comparator, both placebo and caffeine reduced self-reported drowsiness and increased prefrontal blood flow; subjects with L/L 5-HTTLPR genotype showed larger placebo responses.
5 mg/kg caffeine improved ~30-min cycling time-trial performance and modestly altered physiological responses in trained male cyclists.
5 mg/kg caffeine improved ~30-min cycling time-trial performance and modestly altered physiological responses in trained male cyclists.
Single-dose caffeine (6 mg/kg) increased pain-free and maximal walking distances, strength and endurance but worsened balance in patients with intermittent claudication.
Single-dose caffeine (6 mg/kg) increased pain-free and maximal walking distances, strength and endurance but worsened balance in patients with intermittent claudication.
Single-dose caffeine (6 mg/kg) increased pain-free and maximal walking distances, strength and endurance but worsened balance in patients with intermittent claudication.
In 90 male adolescent athletes, acute caffeine (6 mg/kg) improved several performance measures (strength, jump height, sit-ups, and Yo-Yo endurance) versus placebo; these ergogenic effects were independent of ADORA2A and CYP1A2 genotypes.
In 90 male adolescent athletes, acute caffeine (6 mg/kg) improved several performance measures (strength, jump height, sit-ups, and Yo-Yo endurance) versus placebo; these ergogenic effects were independent of ADORA2A and CYP1A2 genotypes.
In 90 male adolescent athletes, acute caffeine (6 mg/kg) improved several performance measures (strength, jump height, sit-ups, and Yo-Yo endurance) versus placebo; these ergogenic effects were independent of ADORA2A and CYP1A2 genotypes.
In 54 active men, creatine loading with or without added caffeine (or coffee) did not provide additional improvements in strength or sprint performance compared with placebo over 5 days.
In a randomized double-blind crossover trial in ~93 completers, paracetamol 1000 mg plus caffeine 130 mg provided more pain relief than placebo and had similar tolerability to placebo and naproxen over 4 hours.
In a randomized double-blind crossover trial in ~93 completers, paracetamol 1000 mg plus caffeine 130 mg provided more pain relief than placebo and had similar tolerability to placebo and naproxen over 4 hours.
In a randomized double-blind crossover trial in ~93 completers, paracetamol 1000 mg plus caffeine 130 mg provided more pain relief than placebo and had similar tolerability to placebo and naproxen over 4 hours.
In 40 habitual coffee consumers in a randomized crossover design, single servings of coffee (160 mg caffeine) increased salivary alpha-amylase and transiently increased salivary gastrin and blood pressure, but did not change salivary cortisol or self-reported GI symptoms.
In 40 habitual coffee consumers in a randomized crossover design, single servings of coffee (160 mg caffeine) increased salivary alpha-amylase and transiently increased salivary gastrin and blood pressure, but did not change salivary cortisol or self-reported GI symptoms.
In 27 pregnant women (19 controls, 8 with GDM) in a randomized crossover trial, acute caffeine (3 mg/kg) impaired insulin sensitivity and raised glucose and C-peptide AUCs in women with gestational diabetes but not in controls.
In a double-blind RCT after elective laparoscopic colectomy (58 analyzed), oral caffeine (100 mg TID) was safe and led to a significantly earlier first bowel movement (by ~18 hours) compared with placebo; other recovery endpoints were not significantly different.
In a double-blind RCT after elective laparoscopic colectomy (58 analyzed), oral caffeine (100 mg TID) was safe and led to a significantly earlier first bowel movement (by ~18 hours) compared with placebo; other recovery endpoints were not significantly different.
In partially sleep-deprived healthy volunteers an acute energy shot improved multiple composite cognitive measures and self-rated alertness for up to 6 hours compared with placebo.
In healthy adults, coadministration of lisdexamfetamine did not materially change caffeine pharmacokinetics (no meaningful CYP1A2 interaction) after single doses.
In healthy adults, coadministration of lisdexamfetamine did not materially change caffeine pharmacokinetics (no meaningful CYP1A2 interaction) after single doses.
In patients recovering from middle cerebral artery stroke and controls, 250 mg caffeine caused a significant reduction in cerebral blood flow and middle cerebral artery velocity versus placebo.
Two-week daily matcha (contains caffeine) preserved attention after mild stress in young adults.
In patients undergoing adenosine myocardial perfusion imaging, supplemental coffee (raising plasma caffeine) did not change measures of perfusion defect or reversibility.
In habitual coffee-drinking middle-aged women, caffeine (50–100 mg) reduced negative mood scores (notably anxiety/sadness); combining aspirin and caffeine did not increase positive mood or show clear abuse potential.
Intravenous caffeine as an opioid adjuvant modestly reduced pain scores and improved drowsiness in advanced cancer patients, but clinical significance was limited.
Six months of 200 mg/day caffeine (alone) in T2D patients with NAFLD did not change hepatic steatosis, fibrosis, enzymes, inflammatory markers or glycemia vs placebo; caffeine reduced total cholesterol by ~20.7 mg/dL.
After prolonged wakefulness in 54 adults, 600 mg caffeine improved performance on the Tower of Hanoi (fewer moves) compared with other groups, with no effect on completion speed.
After outpatient general surgery, analgesia was similar between the codeine+acetaminophen+caffeine regimen and acetaminophen+ibuprofen, but the codeine+caffeine group had more side effects and lower satisfaction.
In moderately obese adults, 12-week intake of glucosyl hesperidin combined with caffeine (especially 50–75 mg caffeine) reduced abdominal fat (mainly subcutaneous), and the highest caffeine dose group showed reductions in body weight and BMI versus placebo.
In 33 obese women followed 16 months, supplementation including 100 mg caffeine did not affect weight-regain or body composition vs controls.
In adults with type 1 diabetes, 200 mg caffeine increased the weekly frequency of symptomatic hypoglycemia and intensified warning symptoms, caused a modest systolic BP rise in women, and slightly improved simple reaction time.
Drinking three cups/day of lightly roasted (higher polyphenols and caffeine) or regular coffee for 12 weeks reduced body fat percentage and increased muscle mass in overweight/obese adults; lightly roasted coffee produced a slightly greater fat percentage reduction.
Randomized double-blind trial testing ephedrine plus caffeine vs placebo for smoking cessation: no difference in 1-year quit rates; combination reduced short-term (first 12 weeks) postcessation weight gain but not weight at 1 year.
Caffeine given before simulated match increased white blood cell counts and augmented some muscle-injury enzyme responses to exercise, suggesting more muscle/endothelial stress.
During 40.5 h sleep deprivation, caffeine reduced sleep drive compared with placebo but did not improve sleep-related recovery measures; other stimulants had differing effects.
During 40.5 h sleep deprivation, caffeine reduced sleep drive compared with placebo but did not improve sleep-related recovery measures; other stimulants had differing effects.
An 8-week randomized trial of an herbal mix (includes 240 mg/day caffeine) produced greater short-term weight and fat loss but more withdrawals and side effects.
In resistance-trained men taking a multi-ingredient supplement containing extended‑release caffeine (~129 mg) for 12 weeks, ultrasound measures of muscle size increased and lower-body fat decreased versus placebo; blood markers remained within normal ranges.
In 100 adolescent athletes, 6 mg/kg caffeine taken 1 hour before testing improved muscular endurance and aerobic performance compared with placebo, independent of CYP1A2 genotype.
Acute ingestion of various energy drinks (contain caffeine plus blends) produced group-specific increases in blood pressure, heart rate, cortisol, and mixed effects on anxiety and working memory.
Six months of 200 mg/day caffeine (alone) in T2D patients with NAFLD did not change hepatic steatosis, fibrosis, enzymes, inflammatory markers or glycemia vs placebo; caffeine reduced total cholesterol by ~20.7 mg/dL.
Ten-week daily caffeine+EGCG drink with/without exercise was associated with improved muscle mass and lower total cholesterol in overweight/obese women.
Intraoperative IV caffeine citrate 200 mg did not reduce early postoperative opioid use; after adjustment caffeine was associated with increased opioid consumption and otherwise no differences in pain or neuropsychological outcomes.
In a 54.5 h total sleep deprivation trial with 50 adults, a single 600 mg caffeine dose maintained performance and alertness relative to placebo, comparable to effective modafinil doses.
A 7-day multi-ingredient supplement (including vitamin D) reduced pain severity and musculoskeletal discomfort vs baseline and performed similarly or better than acetaminophen in this small crossover trial.
In moderately obese adults, 12-week intake of glucosyl hesperidin combined with caffeine (especially 50–75 mg caffeine) reduced abdominal fat (mainly subcutaneous), and the highest caffeine dose group showed reductions in body weight and BMI versus placebo.
In undergraduates, 5 mg/kg caffeine increased systolic blood pressure and altered heart rate/HRV measures and subjective experience 40 minutes after ingestion; expectancies contributed to subjective effects but not objective measures.
In adults with type 1 diabetes, 200 mg caffeine increased the weekly frequency of symptomatic hypoglycemia and intensified warning symptoms, caused a modest systolic BP rise in women, and slightly improved simple reaction time.
Adding 130 mg caffeine to 1000 mg acetaminophen sped absorption and produced stronger, longer pain relief than acetaminophen alone.
In 30 resistance-trained men, 6 mg/kg caffeine before exercise raised growth hormone and testosterone post-exercise in ADORA2A rs5751876 TT homozygotes.
Double-blind randomized placebo-controlled trial of a topical multi-ingredient anti-cellulite product (includes caffeine) in 46 healthy women showed improvement in skin macrorelief (reduced 'orange peel') and increased cutaneous microcirculation versus placebo.
Randomized double-blind placebo-controlled trial of a multi-ingredient topical slimming product (contains caffeine) in 78 women found significant reductions in body circumferences (abdomen, hips/buttocks, waist) from 4 weeks and improvements in cellulite and skin tonicity over 12 weeks.
A single dose of a two-tablet analgesic containing acetaminophen, aspirin, and caffeine relieved migraine pain faster and more effectively than ibuprofen or placebo.
A single dose of a two-tablet analgesic containing acetaminophen, aspirin, and caffeine relieved migraine pain faster and more effectively than ibuprofen or placebo.
A multivitamin–mineral product with guarana improved decision-making speed for about 30–90 min and maintained parasympathetic HRV measures during the first hour compared with caffeine alone or placebo.
In habitual coffee-drinking middle-aged women, caffeine (50–100 mg) reduced negative mood scores (notably anxiety/sadness); combining aspirin and caffeine did not increase positive mood or show clear abuse potential.
Peri-operative oral caffeine did not reduce post-op atrial fibrillation and increased postoperative nausea/vomiting.
In resistance-trained men taking a multi-ingredient supplement containing extended‑release caffeine (~129 mg) for 12 weeks, ultrasound measures of muscle size increased and lower-body fat decreased versus placebo; blood markers remained within normal ranges.
Oral paracetamol+caffeine given prophylactically (75 or 125 mg caffeine repeated) did not reduce rates of postdural puncture headache compared with placebo.
ADORA2A genotype influenced caffeine effects after sleep deprivation: caffeine improved vigilance and reduced recovery-sleep SWA in non-HT4 carriers but was ineffective in HT4 carriers.
Intraoperative IV caffeine citrate 200 mg did not reduce early postoperative opioid use; after adjustment caffeine was associated with increased opioid consumption and otherwise no differences in pain or neuropsychological outcomes.
In 24 adults, an 80 mg‑caffeine energy drink increased self-rated alertness and reduced depression scores; combining it with alcohol did not alter blood alcohol or subjective intoxication versus alcohol alone.
A 7-day multi-ingredient supplement (including vitamin D) reduced pain severity and musculoskeletal discomfort vs baseline and performed similarly or better than acetaminophen in this small crossover trial.
A bioactive combination including caffeine increased resting metabolic rate (thermogenesis) in men, and propranolol (beta-blocker) reduced about half of that thermogenic response.
Ten-week daily caffeine+EGCG drink with/without exercise was associated with improved muscle mass and lower total cholesterol in overweight/obese women.
Ten-week daily caffeine+EGCG drink with/without exercise was associated with improved muscle mass and lower total cholesterol in overweight/obese women.
In 68 SEAL trainees after 72 h sleep deprivation and stress, 200–300 mg caffeine improved vigilance, reaction time, learning, and reduced fatigue/sleepiness vs placebo.
In adults with type 1 diabetes, 200 mg caffeine increased the weekly frequency of symptomatic hypoglycemia and intensified warning symptoms, caused a modest systolic BP rise in women, and slightly improved simple reaction time.
Adding 130 mg caffeine to 1000 mg acetaminophen sped absorption and produced stronger, longer pain relief than acetaminophen alone.
In 30 resistance-trained men, 6 mg/kg caffeine before exercise raised growth hormone and testosterone post-exercise in ADORA2A rs5751876 TT homozygotes.
Randomized double-blind trial testing ephedrine plus caffeine vs placebo for smoking cessation: no difference in 1-year quit rates; combination reduced short-term (first 12 weeks) postcessation weight gain but not weight at 1 year.
Double-blind randomized placebo-controlled trial of a topical multi-ingredient anti-cellulite product (includes caffeine) in 46 healthy women showed improvement in skin macrorelief (reduced 'orange peel') and increased cutaneous microcirculation versus placebo.
Randomized double-blind placebo-controlled trial of a multi-ingredient topical slimming product (contains caffeine) in 78 women found significant reductions in body circumferences (abdomen, hips/buttocks, waist) from 4 weeks and improvements in cellulite and skin tonicity over 12 weeks.
Caffeine given before simulated match increased white blood cell counts and augmented some muscle-injury enzyme responses to exercise, suggesting more muscle/endothelial stress.
A multivitamin–mineral product with guarana improved decision-making speed for about 30–90 min and maintained parasympathetic HRV measures during the first hour compared with caffeine alone or placebo.
Peri-operative oral caffeine did not reduce post-op atrial fibrillation and increased postoperative nausea/vomiting.
In resistance-trained men taking a multi-ingredient supplement containing extended‑release caffeine (~129 mg) for 12 weeks, ultrasound measures of muscle size increased and lower-body fat decreased versus placebo; blood markers remained within normal ranges.
Oral paracetamol+caffeine given prophylactically (75 or 125 mg caffeine repeated) did not reduce rates of postdural puncture headache compared with placebo.
ADORA2A genotype influenced caffeine effects after sleep deprivation: caffeine improved vigilance and reduced recovery-sleep SWA in non-HT4 carriers but was ineffective in HT4 carriers.
In 24 adults, an 80 mg‑caffeine energy drink increased self-rated alertness and reduced depression scores; combining it with alcohol did not alter blood alcohol or subjective intoxication versus alcohol alone.
After prolonged wakefulness in 54 adults, 600 mg caffeine improved performance on the Tower of Hanoi (fewer moves) compared with other groups, with no effect on completion speed.
After outpatient general surgery, analgesia was similar between the codeine+acetaminophen+caffeine regimen and acetaminophen+ibuprofen, but the codeine+caffeine group had more side effects and lower satisfaction.
In 33 obese women followed 16 months, supplementation including 100 mg caffeine did not affect weight-regain or body composition vs controls.
In patients recovering from middle cerebral artery stroke and controls, 250 mg caffeine caused a significant reduction in cerebral blood flow and middle cerebral artery velocity versus placebo.
Two-week daily matcha (contains caffeine) preserved attention after mild stress in young adults.
In 30 resistance-trained men, 6 mg/kg caffeine before exercise raised growth hormone and testosterone post-exercise in ADORA2A rs5751876 TT homozygotes.
Randomized double-blind trial testing ephedrine plus caffeine vs placebo for smoking cessation: no difference in 1-year quit rates; combination reduced short-term (first 12 weeks) postcessation weight gain but not weight at 1 year.
Randomized double-blind placebo-controlled trial of a multi-ingredient topical slimming product (contains caffeine) in 78 women found significant reductions in body circumferences (abdomen, hips/buttocks, waist) from 4 weeks and improvements in cellulite and skin tonicity over 12 weeks.
Caffeine given before simulated match increased white blood cell counts and augmented some muscle-injury enzyme responses to exercise, suggesting more muscle/endothelial stress.
In patients undergoing adenosine myocardial perfusion imaging, supplemental coffee (raising plasma caffeine) did not change measures of perfusion defect or reversibility.
Intravenous caffeine as an opioid adjuvant modestly reduced pain scores and improved drowsiness in advanced cancer patients, but clinical significance was limited.
In 100 adolescent athletes, 6 mg/kg caffeine taken 1 hour before testing improved muscular endurance and aerobic performance compared with placebo, independent of CYP1A2 genotype.
A pre-workout drink containing BHB salts, ~100 mg caffeine and amino acids increased blood ketones and improved time-to-exhaustion by ~8–10% versus water.
Acute ingestion of various energy drinks (contain caffeine plus blends) produced group-specific increases in blood pressure, heart rate, cortisol, and mixed effects on anxiety and working memory.
Six months of 200 mg/day caffeine (alone) in T2D patients with NAFLD did not change hepatic steatosis, fibrosis, enzymes, inflammatory markers or glycemia vs placebo; caffeine reduced total cholesterol by ~20.7 mg/dL.
In moderately obese adults, 12-week intake of glucosyl hesperidin combined with caffeine (especially 50–75 mg caffeine) reduced abdominal fat (mainly subcutaneous), and the highest caffeine dose group showed reductions in body weight and BMI versus placebo.
Large clinical trial showed the fixed triple combination including caffeine produced ~38–45 mm greater pain reduction on a 100-mm VAS at 2 hours compared with baseline in treated headache episodes.