Are energy drinks bad for you? What the evidence says by effect

Are energy drinks bad for you? An occasional can isn't harmful for most healthy adults. Regular or heavy use is different: trials show blood pressure rises, late caffeine hurts sleep, and a 16 oz full sugar can holds close to double the NHS adult sugar limit. Teens, pregnant people and anyone mixing them with alcohol should care most.

Key points

• Caffeine: the FDA and EFSA put up to 400 mg a day as fine for most healthy adults. The problems start with big cans, several cans, or caffeine at night.
• Heart: small randomised trials found energy drinks raised blood pressure in healthy young adults, and one big dose changed the heart's electrical rhythm on an ECG.
• Sleep and mood: EFSA says even 100 mg near bedtime can affect sleep in some adults. In young people, energy drinks go hand in hand with poor sleep and anxiety.
• Teens: the American Academy of Pediatrics says energy drinks have no place in a child's or teenager's diet.
• Alcohol: the CDC warns that energy drinks can hide how drunk you are.

What do energy drinks do to your heart and blood pressure?

In healthy adults, an energy drink raises blood pressure for a few hours. A Mayo Clinic trial in 2015 gave 25 young adults an energy drink or a placebo and found blood pressure rose more after the energy drink. In people not used to caffeine, the rise was more than double.

A bigger dose did more. In a 2019 trial in the Journal of the American Heart Association, Shah and colleagues had 34 healthy volunteers, average age 22, drink 32 ounces of energy drink within an hour. Blood pressure went up compared with placebo, and so did the QT interval, a measure of the heart's electrical recovery that doctors check on an ECG. Thirty two ounces is two large cans, which is not unusual for someone pulling an all nighter.

Neither trial shows harm in a healthy heart from one can. What they show is a real, measurable effect, and that's why the advice changes if you have high blood pressure or a heart condition. If you get chest pain, a racing or irregular heartbeat or fainting after energy drinks, get medical help.

How do energy drinks affect sleep and anxiety?

Caffeine stays in your body for hours, so an afternoon can can still be working at bedtime. EFSA says a single 100 mg dose may affect sleep length and pattern in some adults, especially close to bedtime. That's about one 250 ml Red Bull at 80 mg, or less than one Monster.

Anxiety is on the FDA's own list of signs you've had too much caffeine, along with jitters, a fast heart rate and insomnia.

The research on young people is the most worrying. A 2024 review by Ajibo and colleagues pulled together 57 studies of people up to age 21. Energy drink use was linked with short sleep, poor sleep quality, low marks at school, psychological distress and panic. These studies show links, not proof of cause. Anxious, tired students may reach for cans more. Either way, it's a loop you don't want.

How much sugar is in an energy drink?

A lot, in the full sugar versions. Red Bull lists 27 g of sugar in a 250 ml can. A 16 ounce Monster has about 54 g, according to Caffeine Informer. The NHS daily limit for adults is 30 g of the kind of sugar added to drinks and food, so one Monster is nearly double that on its own.

Energy drinks are acidic too. In a 2016 US study of 379 drinks, Monster Energy measured pH 3.48, inside the range the authors called potentially erosive to teeth.

The zero sugar versions solve the sugar problem and leave the caffeine and the acid exactly where they were. It still isn't a health drink.

Are energy drinks safe for teenagers and students cramming for exams?

Health bodies say no, or not without limits. The American Academy of Pediatrics concluded in 2011 that the caffeine and stimulants in energy drinks have no place in the diet of children and adolescents. EFSA's limit for teens is 3 mg of caffeine per kg a day, which a single big can can pass.

• United States: the FDA notes that the AAP advises against energy drinks for children and teens.
• United Kingdom: the government plans to ban sales of high caffeine energy drinks to under 16s in England from April 2027, subject to Parliament.
• Canada: Health Canada caps energy drinks at 180 mg of caffeine per serving, and the label must say they're not recommended for under 14s.
• Australia and New Zealand: energy drinks can have up to 320 mg of caffeine per litre, and labels must say they're not suitable for young children.

Now the students. If you're cramming for WAEC, JAMB or university finals in Lagos, or for A levels in Leeds, the logic is the same. A can at 10 pm buys you an hour and costs you the sleep that holds what you studied. The NHS says most teenagers need 8 to 10 hours a night, and that cramming all night before an exam is usually a bad idea. I'd go further: a can before an early morning paper is the worst trade of the lot, because the crash tends to land in the exam hall. Timed practice and a full night's sleep are what I'd put before another can.

Is it dangerous to mix energy drinks with alcohol?

It's riskier than alcohol on its own. The CDC says caffeine does not reduce alcohol's effects on your body, even if you feel more alert, and that energy drinks mixed with alcohol may mask the signs of impairment. People can end up drinking more than they meant to.

Feeling sober isn't the same as being sober.

What is the risk, and who should care most

My summary, risk by risk, from the sources above:

Risk	What the evidence says	Who should care most
Blood pressure and heart rhythm	Short rises in blood pressure in healthy adults; a large dose lengthened QT in a trial	People with high blood pressure or heart conditions, anyone drinking several cans at once
Sleep	100 mg near bedtime may affect sleep in some adults, says EFSA	Students, shift workers, anyone drinking after mid afternoon
Anxiety and mood	On the FDA's list of too much caffeine signs; linked with distress in young people	People prone to anxiety or panic, teens
Sugar	27 g in a 250 ml Red Bull, about 54 g in a 16 oz Monster	Anyone drinking full sugar cans daily, people with diabetes
Teeth	Acidic, with pH around 3.5 for Monster in a US study	Daily sippers, teens
Teens	No place in their diet, says the AAP; EFSA limit 3 mg per kg	Under 18s and their parents
Pregnancy	200 mg a day in total from all sources, says EFSA	Pregnant and breastfeeding people
Alcohol	May mask how drunk you are, says the CDC	Anyone who mixes them at parties

For caffeine per can and how many a day add up to 400 mg, see how many energy drinks a day is safe.

How can I cut down on energy drinks?

Slowly, if you drink more than one a day. The FDA says to cut back on caffeine gradually, because withdrawal isn't dangerous but can be unpleasant. In a 2004 review of withdrawal studies, symptoms peaked between about 20 and 51 hours after the last dose. My energy drink withdrawal timeline covers what to expect.

1. Count a normal week first. Every can, and every coffee and cola too.
2. Move the last can earlier. No energy drinks after lunch. Sleep usually improves first.
3. Drop one can a week, or swap a large can for a small one.
4. Plan the moment. Have water, tea or something cold ready for the time you usually reach for a can.

If you want help cutting back, FizzFree tracks the caffeine and sugar you skip for each can you don't drink. I built it to cover energy drinks alongside soda, diet soda and malt drinks, and it adds up the money too. The Taper Dial lowers your weekly allowance step by step, Fizz Map nudges you 10 minutes before a moment you name, and Ride the Fizz is a 90 second craving exercise. There's no streak to lose and no account. Get it on the App Store or Google Play. I compared it with other apps in app to quit energy drinks.

Frequently asked questions

Is one energy drink a day bad for you?

For most healthy adults, one standard can a day stays well under the 400 mg caffeine figure the FDA and EFSA use. The bigger issues are sugar in full sugar cans, the time of day you drink it, and whether you have a heart condition, are pregnant or are under 18.

Can energy drinks cause heart problems?

In trials, energy drinks raised blood pressure in healthy young adults, and a large dose lengthened the QT interval on an ECG. That doesn't prove harm from one can, but it matters if you have a heart condition. Chest pain, a racing heartbeat or fainting need urgent medical help.

Are zero sugar energy drinks better for you?

They're better for sugar and calories, since a full sugar 16 oz Monster has about 54 g of sugar. The caffeine is usually the same, and they're still acidic. So they help with weight and sugar related tooth decay, but not with sleep, anxiety or blood pressure.

Should students drink energy drinks to study?

I wouldn't. The NHS says most teenagers need 8 to 10 hours of sleep and that cramming all night is usually a bad idea. In studies of young people, energy drinks are linked with poor sleep and lower marks. Timed practice and sleep beat a late can.

Are energy drinks worse than coffee?

Not on caffeine alone: the FDA puts a 12 oz brewed coffee at 113 to 247 mg, more than many cans. Energy drinks often add lots of sugar and come in big sizes that are easy to drink fast. A black coffee has no sugar at all.

How I wrote this

On 4 November 2026 I read the FDA and EFSA caffeine pages, the abstracts of the 2015 Mayo Clinic trial, the 2019 JAHA trial, the 2024 review of 57 studies and the 2011 AAP report, the CDC page on alcohol and caffeine, the NHS exam stress page, and the Health Canada and FSANZ rules. Sugar figures come from Red Bull and Caffeine Informer. I looked for reliable figures on energy drink use among Nigerian students and didn't find any I trusted, so I left them out.

This is general information, not medical or veterinary advice. Ask your doctor or vet.

By John Osakwe, founder of Etest Tech Hub. I have built apps and websites since 2015, including Etest CBT, FizzFree and Pawlarm.