Energy drinks: borrowed energy, paid back with interest.

A can gives you sugar, a strong hit of caffeine and a few hours of feeling sharp. Then it takes your sleep. Here's who should never touch them, and a four-week plan from the can to coffee or green tea.

The short version

Best: Water, green tea, black coffee, in the morning.
OK: While you step down: one 250 ml can, before noon, with food.
Never: Under 18, pregnant or breastfeeding, or with a heart condition. Also never with alcohol, and never the "sugar-free" version as the fix.
When: Caffeine of any kind: morning to early afternoon. Nothing in the six hours before bed.
Our take: If you need a can to get through the day, your sleep needs fixing, not your drink.

The one rule: caffeine is a morning thing

An energy drink doesn't give you energy. It hides tiredness. The caffeine blocks the "you're tired" signal in your brain for a few hours, and the sugar gives you a quick lift that drops off again. Fine at 8 am. A disaster at 4 pm, because the caffeine is still in you at bedtime, you sleep badly, and tomorrow you need another can.

So: caffeine only in the morning and early afternoon, and from a cup, not a can.

What's in a can

A standard 250 ml can of Red Bull has 80 mg of caffeine and 27 g of sugar.¹ That's about the caffeine of a cup of filter coffee plus nearly the whole day's sugar limit: the NHS says adults should stay under 30 g of free sugars a day.² Many energy drinks now come in 500 ml cans. Same recipe, double the dose: about 160 mg of caffeine and over 50 g of sugar.

For healthy adults, the European Food Safety Authority (EFSA) says up to 200 mg of caffeine at once, and up to 400 mg spread over a day, raise no safety concerns.³ Two big cans plus a coffee, and you're over. And the other ingredients, like taurine? EFSA found that at the usual amounts they don't change the safety picture for single caffeine doses up to 200 mg.⁴ The problem is the caffeine and the sugar, not the mystery list.

What it does to your body

Your sleep

In a sleep study, 400 mg of caffeine taken even six hours before bed cut total sleep by more than an hour, measured with a sleep monitor.⁵ That's a big dose, about two and a half large cans, but plenty of people get there over a long shift. EFSA notes that even 100 mg close to bedtime can affect sleep in some adults.⁴

Your heart

In a randomised trial with 34 healthy young adults, drinking about a litre of energy drink within an hour raised blood pressure and lengthened the QT interval on the ECG, a measure of how the heart resets between beats, compared with a placebo drink.⁶ In healthy people that's a warning sign, not an emergency. In people with an inherited heart rhythm problem it matters more: in a small trial of 24 people with long QT syndrome, energy drinks raised blood pressure, and three of them had a dangerous jump in QT.⁷

Your blood sugar and weight

Twenty-seven grams of sugar in a few minutes, with nothing to slow it down. Everything our soft drinks guide says about liquid sugar applies here, with caffeine on top.

Who should never drink them

Never, not even one, if you…

are under 18. EFSA's safe level for children and teenagers is 3 mg of caffeine per kg of body weight a day.³ For a 40 kg teenager that's 120 mg, less than one 500 ml can. The American Academy of Pediatrics says stimulant energy drinks have no place in the diet of children and teenagers.⁸ EU law requires drinks with more than 150 mg of caffeine per litre to carry a warning that they're not recommended for children.⁹ England plans to ban sales to under-16s from April 2027.¹⁰ Our line is 18.
are pregnant, trying to get pregnant or breastfeeding. EFSA and the NHS set a limit of 200 mg of caffeine a day from all sources in pregnancy, and the NHS links higher intakes to a higher risk of miscarriage.³¹¹ The EU warning label names pregnant and breastfeeding women too.⁹ Your coffee and tea already count towards that 200 mg. Spend it on those, not on a can of sugar.
have a heart condition: a heart rhythm problem such as long QT syndrome or atrial fibrillation, heart disease, or high blood pressure. Energy drinks raise blood pressure and can affect heart rhythm.⁶⁷

Had palpitations, chest pain or felt faint after an energy drink? Stop, and get it checked by a doctor.

The step-down plan: from can to cup

Don't quit caffeine cold turkey. Withdrawal is real: headache, tiredness, bad mood and poor focus, usually starting 12 to 24 hours after your last dose and lasting two to nine days. In experiments, people got it after stopping as little as 100 mg a day.¹² The trick is to take the sugar out first and lower the caffeine after.

Week	What changes	Caffeine	Sugar
1	Every can becomes a black coffee. Same caffeine, no sugar. Big can? Two coffees.	Same	Zero
2	Nothing with caffeine after 2 pm. The afternoon coffee becomes green tea or water.	Lower	Zero
3	Drop one coffee a day, or swap it for green tea.	Lower	Zero
4	Settle at one or two cups of coffee or tea, all before early afternoon.	Steady	Zero

Roughly: a can of energy drink (250 ml) 80 mg, a cup of filter coffee (200 ml) 90 mg, an espresso 80 mg, a cup of black tea 50 mg, a can of cola 40 mg.⁴ The NHS gives tea, black or green, up to about 75 mg a cup.¹¹ Strength varies a lot with brand and brewing.

Drink by drink

Drink	Caffeine	Sugar	Verdict
Water, sparkling water	0	0 g	Any time
Green or black tea, unsweetened	~50–75 mg	0 g	Before 2 pm
Black coffee, filter or espresso	~80–90 mg	0 g	Before 2 pm
Energy drink, 250 ml	80 mg	27 g	Step-down only
Energy drink, 500 ml	~160 mg	~54 g	Never
"Sugar-free" energy drinks	same as above	0 g, sweeteners	Never
Energy shots, caffeine tablets, pre-workout powders	varies, often high	varies	Never
Energy drink with alcohol	80 mg+	27 g+	Never

Energy drink values from the Red Bull label; coffee and tea from EFSA and the NHS.¹⁴¹¹

"Sugar-free is the fix." It takes out the sugar and leaves every milligram of caffeine. And sweeteners are on our never list: WHO advises against them for weight control, since long-term use showed no benefit for body fat.¹³ They also keep the sweet habit alive. The fix is coffee or tea, not a different can.

"An energy drink keeps you sober." No. EFSA looked at this and concluded that at moderate amounts, caffeine is unlikely to mask how drunk you feel.⁴ You're just as drunk, plus wired, plus a pile of sugar. Mixing is common: in an EFSA survey, about half of adult and teenage energy drink users had drunk them with alcohol.¹⁴ Our alcohol guide puts energy drinks on the forget-it list for mixers.

"It's a sports drink." It's a soft drink with caffeine, whatever the ads with the mountain bikes say. If you want caffeine before training, a black coffee gives you that without the sugar.

Drink, forget

Drink

Water, still or sparkling, lots of it
Black coffee, before 2 pm
Green tea, black tea, unsweetened
Herbal tea in the evening (no caffeine)
Sparkling water with lemon or mint

Forget it

Energy drinks, any size
"Sugar-free", "zero" and "light" energy drinks
Energy shots and caffeine tablets
Energy drinks mixed with alcohol
Caffeinated soft drinks and sweet iced coffee

Drink it where you live

Singapore and Southeast Asia

Small sweet energy drink bottles are in every convenience store. Same rules: they count.
At the kopitiam: kopi-o kosong or teh-o kosong. Caffeine, no sugar.
Exam season: students under 18 skip energy drinks completely. Sleep beats cramming.
Night shifts: caffeine early in the shift only, water in the second half.

Austria, Germany, Switzerland

Red Bull is Austrian. Doesn't make it local health food.
Après-ski "Vodka-Bull" is a double never. Schnaps on its own, if you must, after reading the alcohol guide.
Mate lemonades are soft drinks with caffeine. Same rules.
A kleiner Brauner without sugar, or a Verlängerter, does the job.

During Ramadan, a can at suhoor is the worst choice: sugar now, a crash later, and poor sleep in a month when sleep is already short. Water and a coffee or tea at suhoor work better, and keep caffeine away from the hours before you sleep.

Can't give up the can yet?

250 ml, never 500 ml
One a day, before noon, with breakfast or lunch
Never on an empty stomach and never on a fasting day
Drink a glass of water first, then decide if you still want it

Still a no: energy drinks under 18, in pregnancy or with a heart condition, with alcohol, after 2 pm, more than one a day, and the "sugar-free" switch.

Allergies and intolerances

Energy drinks rarely contain the EU's 14 mandatory allergens, but the swap drinks can, mostly through what you add.¹⁵

Drink	Possible EU allergen	Swap
Coffee or tea with milk	Milk	Black, or a splash of oat or coconut drink
Soy latte	Soy	Black coffee
Oat drink in coffee	Cereals containing gluten (unless labelled gluten-free)	Coconut drink, or black
Almond drink in coffee	Nuts	Oat or coconut drink

Talk to your doctor first if you…

take regular medication: ask your doctor or pharmacist whether it mixes with caffeine
have anxiety, panic attacks or trouble sleeping
have diabetes: the sugar in every can counts
have kidney disease or have been told to limit fluids

How energy drinks fit into your plan

They don't. Your plan uses black coffee and green tea, which are fine even in your fasting window, as long as there's no sugar or milk in them. If your Healthen me answers say you drink energy drinks now, your plan starts with the four-week step-down instead of a ban, and sets your caffeine cut-off by your bedtime.

On Rebel Day the rules for caffeine still stand: nothing after early afternoon. A Rebel Day is for food you enjoy, not a night you don't sleep.

This article is general information, not medical advice. If you have a medical condition, are pregnant or take medication, talk to your doctor before changing what you drink.

Sources

Red Bull. Red Bull Energy Drink ingredients list (caffeine and sugar per 250 ml can). redbull.com
NHS. Sugar: the facts (free sugars, 30 g limit for adults). nhs.uk
EFSA Panel on Dietetic Products, Nutrition and Allergies. Scientific Opinion on the safety of caffeine. EFSA Journal 2015;13(5):4102. doi.org/10.2903/j.efsa.2015.4102
European Food Safety Authority. Caffeine (topic page: safe intakes, caffeine per serving, energy drink ingredients, alcohol). efsa.europa.eu
Drake C, Roehrs T, Shambroom J, Roth T. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. Journal of Clinical Sleep Medicine 2013;9(11):1195–1200. Small study. doi.org/10.5664/jcsm.3170
Shah SA, Szeto AH, Farewell R et al. Impact of high volume energy drink consumption on electrocardiographic and blood pressure parameters: a randomized trial. Journal of the American Heart Association 2019;8(11):e011318. doi.org/10.1161/JAHA.118.011318
Gray B, Ingles J, Medi C, Driscoll T, Semsarian C. Cardiovascular effects of energy drinks in familial long QT syndrome: a randomized cross-over study. International Journal of Cardiology 2017;231:150–154. Small study. doi.org/10.1016/j.ijcard.2016.12.019
Schneider MB, Benjamin HJ; American Academy of Pediatrics. Sports drinks and energy drinks for children and adolescents: are they appropriate? Pediatrics 2011;127(6):1182–1189. doi.org/10.1542/peds.2011-0965
Regulation (EU) No 1169/2011 on food information to consumers, Annex III point 4.1 (beverages with high caffeine content). eur-lex.europa.eu/eli/reg/2011/1169/oj
UK Department of Health and Social Care. Children's health further protected with energy drinks ban. News release, 16 July 2026. gov.uk
NHS. Foods to avoid in pregnancy (caffeine limit and caffeine per drink). nhs.uk
Juliano LM, Griffiths RR. A critical review of caffeine withdrawal: empirical validation of symptoms and signs, incidence, severity, and associated features. Psychopharmacology 2004;176(1):1–29. doi.org/10.1007/s00213-004-2000-x
World Health Organization. WHO advises not to use non-sugar sweeteners for weight control in newly released guideline. News release, 15 May 2023. who.int
European Food Safety Authority. Energy drinks report (Zucconi S et al. Gathering consumption data on specific consumer groups of energy drinks. EFSA Supporting Publications 2013:EN-394). News, 6 March 2013. efsa.europa.eu
Regulation (EU) No 1169/2011 on food information to consumers, Annex II (the 14 allergens). eur-lex.europa.eu/eli/reg/2011/1169/oj

Keep reading

Coffee drinks: take the syrup out
Black coffee is fine, even in your fasting window. The caramel latte, the frappé and the kopi with four spoons of sugar are desserts. A three-week plan to take the syrup out without hating your mornings.
Soft drinks: getting off the sugar water
A can of cola is a day's sugar in two minutes, and juice is no way out. What sugary drinks do to your body, a four-week step-down to sparkling water, and why "zero" isn't our swap.
Alcohol: what you can drink without wrecking the plan
Clear spirits and dry wine, with food, now and then. Which drinks fit, which ones wreck the plan, and why you never drink on an empty stomach.