Caffeine vs WaterEnergy drinks
How Many Energy Drinks a Day Is Safe? The Answer by Brand and Can Size
How many energy drinks a day is safe? For most adults the limit is 400 mg of caffeine: five small Red Bulls, but only two Celsius or one Bang. See every can.
The short answer
- For healthy adults, the limit is 400 mg of caffeine a day from all sources, and no more than about 200 mg at once.
- That's up to 5 small Red Bulls (8.4 oz, 80 mg), 2 Monsters (16 oz, 160 mg), 2 Celsius (200 mg) or 1 Bang (300 mg) a day, with no coffee on top.
- Some cans go over the 200 mg single-dose guide by themselves: Bang, Reign, Celsius Heat, 24 oz Monster.
- For teens, pregnancy, heart conditions or anxiety, the safe number is lower, often zero. Ask your doctor.
How many energy drinks a day is safe depends almost entirely on one thing: how much caffeine is in the can. A small Red Bull has 80 mg. A Bang has 300 mg. So "two a day" can mean 160 mg, well within the limits, or 600 mg, well over them.
Here's how to work out your number, with the cans-per-day figure for popular energy drinks and the situations where the answer is lower.
The limits: 400 mg a day, 200 mg at a time
Two major food safety agencies set the numbers most people use:
- The FDA cites 400 mg a day as an amount "not generally associated with negative effects" for most adults.
- The European Food Safety Authority (EFSA) agrees on 400 mg a day for healthy adults, and adds that single doses up to 200 mg (about 3 mg per kg of body weight) don't raise safety concerns.
Both limits cover caffeine from all sources: coffee, tea, soda, pre-workout and pills count too. And both are for healthy adults, not teenagers or pregnant women. There's more on how the limits were set in how much caffeine is too much.
How many energy drinks a day, by brand
Maximum cans a day before you hit 400 mg, assuming no other caffeine. Caffeine figures are from the Caffeine vs Water drink catalog.
| Energy drink | Size | Caffeine | Max cans a day | Over 200 mg at once? |
|---|---|---|---|---|
| Red Bull | 8.4 oz / 250 ml | 80 mg | 5 | No |
| Red Bull | 12 oz / 355 ml | 114 mg | 3 | No |
| Red Bull | 16 oz / 473 ml | 151 mg | 2 | No |
| Red Bull | 20 oz / 591 ml | 198 mg | 2 | Just under |
| Monster Energy | 16 oz / 473 ml | 160 mg | 2 | No |
| Monster Zero Ultra | 16 oz / 473 ml | 150 mg | 2 | No |
| Monster Energy | 24 oz / 710 ml | 240 mg | 1 | Yes |
| Rockstar | 16 oz / 473 ml | 160 mg | 2 | No |
| Celsius | 12 oz / 355 ml | 200 mg | 2 | At the limit |
| Alani Nu Energy | 12 oz / 355 ml | 200 mg | 2 | At the limit |
| Ghost Energy | 16 oz / 473 ml | 200 mg | 2 | At the limit |
| Prime Energy (US) | 12 oz / 355 ml | 200 mg | 2 | At the limit |
| 5-hour Energy | 1.93 oz / 57 ml | 200 mg | 2 | At the limit |
| Celsius Essentials | 16 oz / 473 ml | 270 mg | 1 | Yes |
| Bang | 16 oz / 473 ml | 300 mg | 1 | Yes |
| Reign | 16 oz / 473 ml | 300 mg | 1 | Yes |
| Celsius Heat | 16 oz / 473 ml | 300 mg | 1 | Yes |
| Monster (UK) | 500 ml | 160 mg | 2 | No |
| Relentless (UK) | 500 ml | 160 mg | 2 | No |
Numbers are rounded down to whole cans. Three 12 oz Red Bulls come to 342 mg, which leaves room for one small coffee; a fourth takes you to 456 mg. Brands also change recipes and regional versions differ, so check the label: a Monster in the UK and a Monster in the US have the same 160 mg, but Bang in Canada has 180 mg instead of 300.
Why "a day" isn't the whole story
Staying under 400 mg doesn't mean any pattern is fine. Two things matter as much as the daily total.
How fast you drink them. Caffeine peaks about 45–50 minutes after a drink. Two cans back to back put 300–600 mg into your bloodstream within an hour. In a 2019 randomized trial, young healthy adults who drank 32 oz of energy drink within an hour had a larger increase in their QTc interval (a measure of the heart's electrical recovery) and higher blood pressure than after a placebo drink. The changes were small, but the authors flagged them as a concern for people with heart conditions.
When you drink them. The same two Monsters at 9 am and 3 pm leave about 88 mg in a typical adult at 11 pm, nearly twice the 50 mg bedtime target. Two cans at 8 am and 11 am leave far less. See energy drinks and sleep for the latest time for every can, or test your own timing with the bedtime caffeine calculator.
When the safe number is lower
- Teens and children. The American Academy of Pediatrics says caffeine and other stimulants in energy drinks "have no place in the diet of children and adolescents". EFSA suggests no more than 3 mg per kg a day for young people, about 150 mg for a 50 kg (110 lb) teen: a single 16 oz Monster. England will ban sales of high-caffeine energy drinks to under-16s from April 2027. More in caffeine for teens.
- Pregnancy and breastfeeding. The limit drops to 200 mg a day, which is one 200 mg can with nothing else. See caffeine and pregnancy.
- Heart conditions, high blood pressure or palpitations. Talk to your doctor before drinking energy drinks at all. See caffeine and heart palpitations.
- Anxiety, or medication that interacts with caffeine. A lower limit is sensible; ask your doctor or pharmacist.
Signs you're having too many
Jitters, a racing or pounding heart, anxiety, an upset stomach, headaches, and trouble sleeping are the usual signs. If you get chest pain, fainting or a very fast or irregular heartbeat after energy drinks, get medical help. The FDA notes that toxic effects such as seizures can occur with rapid intake of around 1,200 mg.
If you need two or three cans just to feel normal, that's a sign of tolerance. Cutting back works best slowly; how to cut back on caffeine has a week-by-week plan.
Frequently asked questions
How many energy drinks a day is safe?
For healthy adults, enough to stay under 400 mg of caffeine a day from all sources and about 200 mg at once. That's up to five 8.4 oz Red Bulls, two 16 oz Monsters or two 200 mg cans like Celsius, or one 300 mg can like Bang, with no other caffeine.
How many Red Bulls a day is too much?
More than five 8.4 oz cans (80 mg each), three 12 oz cans (114 mg) or two 16 oz cans (151 mg) takes a healthy adult past 400 mg a day on Red Bull alone. Any coffee or tea you drink lowers that number.
Is 2 energy drinks a day too much?
Two small or medium cans (up to about 200 mg each) keep most healthy adults within 400 mg, if they have little other caffeine. Two 300 mg cans such as Bang come to 600 mg, which is over the limit. Two cans in the afternoon are also likely to affect sleep.
How many Monsters a day can you drink?
A 16 oz Monster has 160 mg of caffeine, so two a day (320 mg) is within the 400 mg limit for healthy adults with little other caffeine. A 24 oz Monster has 240 mg, so one is the limit.
Can teenagers drink energy drinks?
Pediatric experts advise against it. The American Academy of Pediatrics says energy drinks have no place in the diet of children and adolescents, and England is banning sales of high-caffeine energy drinks to under-16s from April 2027.
Sources
- U.S. FDA. Spilling the Beans: How Much Caffeine is Too Much?
- EFSA. Caffeine (400 mg a day, 200 mg single doses, 3 mg/kg for children and adolescents).
- Shah SA, et al. Impact of high volume energy drink consumption on electrocardiographic and blood pressure parameters: a randomized trial. J Am Heart Assoc, 2019.
- American Academy of Pediatrics. Sports drinks and energy drinks for children and adolescents: are they appropriate? Pediatrics, 2011.
- GOV.UK. Children's health further protected with energy drinks ban. July 2026.
- Red Bull. How much caffeine is in a can of Red Bull Energy Drink?
General wellness information, not medical advice. If you're pregnant, have a heart condition, or take medication that affects caffeine, check your limits with a doctor.