Energy drinks: what a single can measurably does

A single energy drink raises blood pressure. That is the best-measured fact on this page. Across 17 randomised trials in healthy adults, systolic pressure, the top number, went up by about 4.7 mmHg an hour after the can, and diastolic, the bottom number, by 4.5 mmHg at two hours. Resting heart rate and the QT interval on the ECG did not change significantly. The sugar is the other plain number. The British table gives 42 kcal and 11 g of sugar per 100 ml, so a 16 fl oz can of the sugared kind carries roughly 50 g. Whether a can makes you faster is the contested part. A pooling of 34 studies found small to moderate gains in strength, endurance and jumping and none in sprinting, and the trials underneath it disagree with each other. Recreational runners took about 30 seconds off a 5 km run. Professional volleyball players gained nothing. The EU refused the makers permission to print that these drinks sharpen alertness, focus or memory, which is a regulator's verdict on a claim file rather than a measurement. Nearly every trial here gave one can, once, to young healthy adults. What a daily habit does over years has not been tested in anything our cards hold.

The numbers, per 100 g

How much is actually in it

• A carbonated energy drink carries about 42 kcal and 11 g of sugar per 100 ml in the British table, so a 16 fl oz can of the sugared kind holds roughly 50 g of sugar. The B-vitamin content varies from zero to above the daily value per 100 g, and several times it in a 16 fl oz can, between US products. — Energy drink, carbonated in CoFID; 12 branded energy drink records in USDA SR Legacy; Energy Drink in FNDDS (n = CoFID one entry; USDA 12 records; FNDDS 8 measures) Evidence E source
  CoFID 17-672 per 100 ml: 42 kcal, 11.1 g sugars, 60 mg sodium. USDA 174171 (AMP) per 100 g: riboflavin 0.34 mg, vitamin B12 0.6 µg, niacin 2 mg; across 12 USDA records riboflavin 0 to 1.6 mg, B12 0 to 3.77 µg, niacin 0 to 10.16 mg. FNDDS 2710756: 8 fl oz can 248 g, 12 fl oz 372 g, 16 fl oz 496 g, 24 fl oz 744 g

What a real portion looks like

• US surveys from 1999 to 2011 put usual caffeine intake at 25 mg a day in children aged 2 to 11 and 50 mg in 12 to 17 year olds. Energy drink use was rising, and 10% of 12 to 19 year olds exceeded Canadian caffeine limits in 2009-2010. — US children and adolescents in NHANES 2007-2010 and the Kantar Worldpanel beverage panel (n = national surveys) Evidence C source
  Usual caffeine 25 and 50 mg/d by age; energy drink use 2 to 30% depending on study; 10% of 12-19 y and 10-25% of caffeine consumers above Canadian maximal guidelines

What it does to your health

• A meta-analysis of 34 studies found energy drinks improve muscle strength and endurance, endurance tests, jumping and sport-specific actions by small to moderate effect sizes of 0.3 to 0.5, but not sprinting, and the gain tracked taurine dose rather than caffeine dose. — Athletes and active adults in 34 studies published 1998 to 2015 (n = 34 studies) Evidence A source
  ES 0.49 muscle strength and endurance, 0.53 endurance tests, 0.29 jumping, 0.51 sport-specific actions, sprinting 0.14 not significant; meta-regression slope for taurine p = 0.04, caffeine p = 0.21
• In 18 recreational runners, Red Bull before a 5-km treadmill time trial cut the time by about 30 seconds, from 1444 to 1413 seconds, without changing perceived exertion. — 18 recreational endurance runners, 13 men and 5 women, mean age 20, double-blind crossover (n = 18) Evidence B source
  5-km time 1413.2 vs 1443.6 s (p = 0.016); RPE and affect unchanged
• In 19 professional female volleyball players, an energy drink taken before testing did not improve vertical jump, anaerobic power or grip strength beyond a 1 kg difference in one hand. — 19 professional female volleyball players, Costa Rica, mean age 22, randomised double-blind crossover (n = 19) Evidence B source
  No session by time interaction for any test; right grip 34.6 vs 33.4 kg regardless of time (p < 0.05)
• In 10 graduate students tested at night, an energy drink kept P300 latency, motor reaction time and well-being scores at baseline while all three deteriorated by midnight on placebo. — 10 graduate students, double-blind placebo-controlled, measured before and one hour after ingestion at night (n = 10) Evidence B source
  P300 latency and motor reaction time lengthened on placebo, unchanged with the drink; well-being, vitality and social extrovertedness scores fell on placebo only

Safety, limits and interactions

• A 2024 meta-analysis of 17 randomised trials found that one energy drink raises systolic blood pressure by about 4.7 mmHg at 60 to 80 minutes and diastolic by 4.5 mmHg at 2 hours in healthy adults. Resting heart rate and QT interval did not change significantly. — Healthy adults in 17 randomised controlled trials of acute energy drink consumption (n = 17 trials) Evidence A source
  SBP +4.71 mmHg (95% CI 2.97 to 6.45, GRADE moderate) at 60-80 min; DBP +4.51 mmHg (2.60 to 6.42, GRADE low) at 120 min; cardiac output +0.43 L (0.08 to 0.77, GRADE very low); heart rate and QT/QTc not significant
• In a crossover pilot of 9 healthy adults, four servings of Red Bull in one day raised mean 24-hour systolic blood pressure to 123 mmHg against 117 mmHg on the same 320 mg of caffeine in water, so the drink did more than its caffeine. — 9 healthy normotensive non-smokers aged 18 to 45, single-centre open-label crossover with 24-hour ambulatory monitoring (n = 9) Evidence B source
  24-h SBP 123.2 vs 117.4 mmHg (p = 0.04), DBP 73.6 vs 68.2 (p = 0.02), MAP 90.1 vs 84.8 (p = 0.03) with energy drink vs caffeine control
• In 80 healthy medical students given carbonated water or one of three energy drinks, systolic blood pressure rose significantly at 30 minutes with two of the drinks and one drink shortened the QTc interval and raised salivary cortisol. — 80 healthy medical students, mean age 21, 62.5% male, four arms (n = 80) Evidence B source
  30-min SBP up in groups A and C; group B: 1-h DBP up, QTc shortening, salivary cortisol up; N-back scores up in group A
• In 14 male sprint swimmers, a caffeinated energy drink improved jump height, grip force, 50-m time and peak power by 1 to 10%, while insomnia, muscle pain and headache in the following hours were no more common than with the caffeine-free version. — 14 male competitive sprint swimmers, randomised counterbalanced crossover (n = 14) Evidence B source
  Jump 49.4 vs 50.9 cm, grip 481 vs 498 N, 50 m 27.8 vs 27.5 s, peak power 273 vs 303 W (all P < 0.05); insomnia 7 vs 7%, headache 0 vs 7% (P > 0.05)
• A 2026 case report describes a 37-year-old man who developed potassium of 2.0 mmol/l, leg paralysis, ECG changes and rhabdomyolysis after drinking more than three cans of energy drink a day, about 480 mg of caffeine or more. — One 37-year-old man, Denmark (n = 1) Evidence D source
  Severe hypokalaemia (P-potassium 2.0 mmol/l), elevated creatine kinase, muscle weakness and leg paralysis; recovery with intravenous potassium and fluids
• Laboratory measurement of 43 energy drinks and 24 pre-workout beverages gave a mean pH of 3.3, below the threshold at which enamel dissolves, so most were classed as erosive. — 67 commercial beverages, 43 energy drinks and 24 pre-workout drinks, plus a survey of 113 amateur athletes (n = 43 energy drinks) Evidence D source
  Mean pH 3.3, below the critical threshold for enamel; 51% of surveyed athletes used such drinks

What people believe that the data does not support

• In 8 healthy men, a 355 ml sugar-free Red Bull raised resting energy expenditure by 4%, exactly as much as 120 mg of caffeine in water, so taurine, glucuronolactone and B vitamins added nothing to the thermic effect. — 8 healthy young men, randomised crossover, indirect calorimetry for 2 hours (n = 8) Evidence B source
  REE +4% with both sugar-free Red Bull and water plus 120 mg caffeine; RQ briefly raised by the drink only
• The EU refused the claim that caffeinated carbohydrate energy drinks enhance mental performance, reaction time, alertness, focus and memory or give an energy boost, so none of that wording may appear on a can in the EU. — EU register of nutrition and health claims, snapshot of 2026-09-21 Evidence E source
  Status Non-authorised

Who this works differently for

• A rapid review of 46 studies in children and young people found energy drink use strongly associated with health-damaging behaviours and with headaches, stomach aches, hyperactivity and insomnia, with some sign of a dose-response. — Children and young people aged mostly 11 to 18 in 46 studies, mostly cross-sectional, North America and Europe (n = 46 studies) Evidence C source
  Strong positive association with risk behaviours and with headaches, stomach aches, hyperactivity and insomnia; some evidence of dose-response
• A systematic review of 104 studies in under-18s confirmed a shared pattern of energy drink consumption with alcohol, tobacco and drug use, violent and risky behaviour and poor diet, with only about 10% of the evidence longitudinal. — Children and adolescents aged 0 to 18 in 104 original articles published to April 2021 (n = 104 studies) Evidence C source
  Consistent association with polysubstance use, violent and risky behaviours, sugar-sweetened beverages and junk food; only about 10% longitudinal
• EU law requires any drink with more than 150 mg of caffeine per litre to carry the words High caffeine content, not recommended for children or pregnant or breast-feeding women, next to the caffeine content in mg per 100 ml. — Beverages other than coffee and tea sold in the EU, including energy drinks Evidence E source
  Mandatory warning for caffeine above 150 mg/l, in the same field of vision as the name of the beverage, with caffeine content in mg per 100 ml

The bottom line

If you drink one now and then, the measurable cost is a few points of blood pressure for an hour or two and about 50 g of sugar in a large can of the sugared kind. In 80 medical students, two of three drinks raised systolic pressure within 30 minutes, and one of them shortened the QTc interval and pushed up cortisol in saliva. Whether the extra ingredients matter beyond the caffeine has been asked in two tiny trials, and the answer depends on what was measured. In 9 adults, four cans of Red Bull in a day pushed 24-hour systolic pressure to 123 mmHg against 117 on the same 320 mg of caffeine dissolved in water, so the drink did more than its caffeine. In 8 men, a 355 ml sugar-free can raised resting energy expenditure, the calories you burn sitting still, by 4 percent, exactly as much as 120 mg of caffeine in water, so taurine, glucuronolactone and the B vitamins added nothing there. Nine and eight people are pilot numbers. Treat both as questions waiting for a bigger trial, and do not read the 4 percent as a weight tool, because nobody measured weight. The performance story has the same shape. Sprint swimmers given a caffeinated version of the drink improved jump, grip, 50 m time and peak power by 1 to 10 percent, and reported no more insomnia, muscle pain or headache afterwards than on the caffeine-free version. Professional female volleyball players improved at nothing. Ten graduate students tested at midnight held their reaction time while the placebo group slowed. The pooled analysis of 34 studies says the gain tracked the taurine dose rather than the caffeine dose, which is a statistical association across studies. No trial in our set varied taurine on its own. Two parts of this page concern people who were in none of those trials, children and pregnant women. The EU makes any drink over 150 mg of caffeine per litre carry the words high caffeine content, not recommended for children or pregnant or breast-feeding women. For children, the evidence behind that is a pile of surveys, 46 studies and then 104, mostly cross-sectional, in which teenagers who drink energy drinks also report more headaches, stomach aches, hyperactivity and insomnia, and more alcohol, tobacco, drugs, risky behaviour and worse diets. Only about 10 percent of that work followed anyone over time, so it shows company and cannot show cause. In the US, usual caffeine intake was 25 mg a day at ages 2 to 11 and 50 mg at 12 to 17, and one in ten 12 to 19 year olds was over the Canadian ceiling by 2009-2010. Two smaller hazards are specific. Forty-three energy drinks and 24 pre-workout drinks measured in a lab averaged pH 3.3, on the acid side of the line where tooth enamel dissolves. And a 37-year-old man drinking more than three cans a day, about 480 mg of caffeine or more, ended up with blood potassium of 2.0 mmol/l, leg paralysis, ECG changes and muscle breakdown. That is one man, so it is a warning about heavy daily use and nothing more. The EU refusal in the first paragraph is a verdict on the claim file for these drinks, not a measurement of caffeine, which has its own EFSA opinions on alertness that this entry does not cover. What we cannot tell you: our cards hold no daily caffeine limit from a health body, no data on interactions with medicines, nothing on mixing with alcohol, nothing on pregnancy beyond the label wording, and no trial longer than a day. If you have high blood pressure, a heart rhythm problem, or take medicine for either, the 4.7 mmHg above was measured in people who had none of those, and the question belongs with the person treating you.

Sources

1. endr-c3-17 · reference dataset
   CoFID 17-672 Energy drink, carbonated — Energy 42 kcal · Total sugars 11.1 g · Sodium 60 mg || USDA 174171 Beverages, Energy drink, AMP — riboflavin 0.34 mg · vitamin B12 0.6 µg · niacin 2 mg; 12 records riboflavin 0–1.6 · B12 0–3.77 · niacin 0–10.16 || FNDDS 2710756 Energy Drink — 1 can or bottle (8 fl oz) 248 g · (12 fl oz) 372 g · (16 fl oz) 496 g · (24 fl oz) 744 g
   CoFID 2021, Public Health England / OGL v3.0; USDA SR Legacy FDC 174171 and siblings; USDA FNDDS 2021-2023 fdc_id 2710756 · checked 2026-09-23
2. endr-c3-05 · review of national surveys
   The usual intakes of caffeine were 25 and 50 mg/d for children and adolescents aged 2-11 and 12-17 y, respectively (NHANES 2007-2010)...In 2009-2010, 10% of 12- to 19-y-olds and 10-25% of caffeine consumers (aged 12-19 y) had intakes exceeding Canadian maximal guidelines.
   Adv Nutr, 2015 · checked 2026-09-23
3. endr-c3-02 · meta-analysis
   Overall, ED ingestion improved physical performance in muscle strength and endurance (ES = 0.49; p < 0.001), endurance exercise tests (ES = 0.53; p < 0.001), jumping (ES = 0.29; p = 0.01) and sport-specific actions (ES = 0.51; p < 0.001), but not in sprinting (ES = 0.14; p = 0.06). The meta-regression demonstrated a significant association between taurine dosage (mg) and performance (slope = 0.0001; p = 0.04), but not between caffeine dosage (mg) and performance (slope = 0.0009; p = 0.21).
   Eur J Nutr, 2017 · checked 2026-09-23
4. endr-c3-08 · RCT
   Performance improved with the energy drink compared with placebo (Red Bull: 1,413.2 ± 169.7 vs. PLA: 1,443.6 ± 179.2 seconds; p = 0.016), but there were no differences in RPE, affect, session RPE, session affect, or the distance covered at 5-minute splits between the two 5-km time trials (p > 0.05).
   J Strength Cond Res, 2016 · checked 2026-09-23
5. endr-c3-09 · RCT
   A 3 × 2 repeated-measures ANOVA revealed no significant within-session and measurement time interactions for each performance test...The acute ingestion of an ED did not improve physical performance of professional Costa Rican female volleyball players.
   Int J Sport Nutr Exerc Metab, 2015 · checked 2026-09-23
6. endr-c3-12 · RCT
   At the end of the experiment (midnight), P300 latency and motor reaction time were significantly longer compared with baseline measurements in the placebo group, but were unchanged in the energy drink group...As half of the study cohort were non-caffeine users, the described effects cannot be explained in terms of the restoration of plasma caffeine levels to normal following caffeine withdrawal.
   Amino Acids, 2000 · checked 2026-09-23
7. endr-c3-01 · meta-analysis of RCTs
   More pronounced effects were seen on SBP at 60-80 minutes (4.71 mmHg; 95% CI: 2.97–6.45; GRADE: moderate), DBP at 120 minutes (4.51 mmHg; 95% CI: 2.60–6.42; GRADE: low), and CO at 30-40 minutes after consumption (0.43 L; 95% CI: 0.08–0.77; GRADE: very low). The effects of ED consumption on resting heart rate and QT/QTc interval were not significant (P ≤ 0.05).
   Nutr Rev, 2024 · checked 2026-09-23
8. endr-c3-06 · RCT
   subjects received either an energy drink (Red Bull Energy Drink, each dose containing 80 mg of caffeine and 1000 mg of taurine in an 8.3-oz serving) or a control (compounded caffeine solution, each dose containing 80 mg of caffeine solution in 8 oz of bottled water) at 0800, 1100, 1500, and 1900 hours and underwent 24-hour ABPM...Mean 24-hour SBP (123.2 vs 117.4 mm Hg, p = 0.04), DBP (73.6 vs 68.2 mm Hg, p = 0.02), and MAP (90.1 vs 84.8 mm Hg, p = 0.03) were significantly higher during energy drink supplementation versus caffeine supplementation.
   Ann Pharmacother, 2012 · checked 2026-09-23
9. endr-c3-07 · RCT
   Eighty young healthy medical students were included in the study...Thirty-minute SBP increased significantly in the A and C groups. The B group exhibited a diminution of the percentage of the 1-h SBP increase, an increase of 1-h DBP and QTc shortening. HR showed an increase in the percent change in the A and C groups. Cortisol salivary levels increased in the B group.
   Eur J Nutr, 2017 · checked 2026-09-23
10. endr-c3-10 · RCT
    the caffeinated energy drink reduced the time needed to complete the 50 m simulated swimming competition (27.8 (SD 3.4) v. 27.5 (SD 3.2) s; P<0.05), and it increased peak power (273 (SD 55) v. 303 (SD 49) W; P <0.05)...The caffeinated energy drink did not modify the prevalence of insomnia (7 v. 7%), muscle pain (36 v. 36%) or headache (0 v. 7%) during the hours following its ingestion (P>0.05).
    Br J Nutr, 2015 · checked 2026-09-23
11. endr-c3-13 · case report
    A 37-year-old man developed severe hypokalemia and rhabdomyolysis after daily intake of over three cans of energy drink (≥ 480 mg caffeine). Clinical features included muscle weakness, leg paralysis, and ECG changes. Blood tests revealed severe hypokalaemia (P-potassium 2.0 mmol/l; ABG 1.5 mmol/l) and elevated creatine kinase levels.
    Ugeskr Laeger, 2026 · checked 2026-09-23
12. endr-c3-14 · laboratory analysis
    A total of 67 beverages were examined, comprising 43 energy drinks and 24 sports supplementation beverages, also known as pre-workout or pre-training beverages...The findings indicated an average pH of 3.3 among the studied beverages, indicating a pH below the critical threshold.
    BMC Oral Health, 2024 · checked 2026-09-23
13. endr-c3-11 · RCT
    sfRB and water + caffeine both increased REE to the same degree (+4%)...The stimulatory effects of sfRB on REE are mimicked by water + caffeine, indicating that the auxiliary ingredients do not influence this thermic effect. The metabolic effects of sfRB are primarily due to caffeine alone.
    Obesity (Silver Spring), 2015 · checked 2026-09-23
14. endr-c3-15 · claims register
    POL-HC-6839 Caffeinated carbohydrate containing energy drinks Enhances mental performance, reaction time, alertness, focus and memory. Energises. Gives you an energy boost. Enhances mental energy. Enhances alertness quickly. Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-6839, snapshot 2026-09-21 · checked 2026-09-23
15. endr-c3-03 · systematic review of observational studies
    A total of 410 studies were located, with 46 meeting the inclusion criteria. The majority employed a cross-sectional design, involved participants aged 11-18 years...Several studies identified a strong, positive association between the use of energy drinks and higher odds of health-damaging behaviours, as well as physical health symptoms such as headaches, stomach aches, hyperactivity and insomnia. There was some evidence of a dose-response effect.
    BMJ Open, 2016 · checked 2026-09-23
16. endr-c3-04 · systematic review of observational studies
    which allowed to select 104 original articles. Only ~ 10% of the papers provided results based on longitudinal analyses. A common pattern of ED consumption and polysubstance use, including alcohol, tobacco, and soft and hard drugs, was still confirmed in adolescents; violent and risky behaviors were also related to a higher ED consumption.
    Eur J Pediatr, 2022 · checked 2026-09-23
17. endr-c3-16 · regulation
    contain caffeine, from whatever source, in a proportion in excess of 150 mg/l...'High caffeine content. Not recommended for children or pregnant or breast-feeding women' in the same field of vision as the name of the beverage
    Regulation (EU) No 1169/2011 on the provision of food information to consumers, Annex III, consolidated text · checked 2026-09-23