Caffeine and Energy Drinks: Benefits, Limits and Risks

Why: The FDA says medical experts, including the American Academy of Pediatrics, advise against energy drinks for children and teens because of sugar and caffeine, and that too much can cause fast heart rate, palpitations, high blood pressure, anxiety and sleep, digestive and dehydration problems. A review of 57 studies linked energy drink use in young people to short and poor sleep, psychological distress, tooth decay and risk behaviours, though these are mostly associations that do not show cause. A small randomised trial in 26 healthy children and teenagers found more extra heartbeats from the upper chambers after an energy drink but no dangerous rhythms.

Who it applies to: Children and teenagers; parents; young athletes.

Try instead: Water, milk and a regular sleep routine. Talk to a pharmacist or doctor about tiredness in a young person.

Why: The NHS says pregnant people should not have more than 200 mg of caffeine a day, linking too much caffeine to a higher chance of miscarriage and stillbirth. The FDA recommends talking to your provider about limiting caffeine if pregnant, trying to become pregnant or breastfeeding. A meta-analysis of 60 publications found higher risks of miscarriage, stillbirth and low birth weight with more caffeine and no threshold below which associations vanished, though the authors noted the sizes were modest and may reflect study bias.

Who it applies to: Anyone pregnant, trying to conceive or breastfeeding.

Try instead: Count caffeine from every source, including tea, chocolate and energy drinks, and ask your midwife or doctor for your own limit.

Why: A meta-analysis of studies in 546 healthy people found caffeine raised anxiety scores, with a much larger effect at high doses, especially above 400 mg. In a meta-analysis of studies in people with panic disorder, 51.1 percent of 237 patients had a panic attack after a large single caffeine dose (about 5 cups of coffee) and none after placebo, compared with 1.7 percent of healthy controls.

Who it applies to: People with anxiety, panic attacks or a sensitive nervous system.

Try instead: Choose smaller amounts, lower-caffeine drinks or decaf, and talk to a health professional about anxiety that is hard to manage.

Anxiety disorders → Panic attacks →

Why: In a randomised home study, 400 mg of caffeine even 6 hours before bedtime disturbed sleep compared with placebo.

Who it applies to: Anyone whose sleep is light, broken or short.

Try instead: Move your last caffeine earlier and switch to water or a caffeine-free drink.

Stay Asleep Through the Night →

Why: The energy drink trials mostly studied healthy young people and found short-term rises in blood pressure and QTc; groups with heart conditions were not covered and the AHA statement says data on high doses are limited and generally suggest harm.

Who it applies to: Anyone with a heart rhythm problem, high blood pressure or heart disease, or who has had fainting or palpitations.

Try instead: Ask your clinician whether caffeine is suitable for you before using energy drinks or caffeine products.

Why: The FDA estimates toxic effects such as seizures can occur with rapid consumption of about 1,200 mg, less than half a teaspoon of pure caffeine, and says pure and highly concentrated products can cause death. They have been sold in bulk packaging that requires buyers to measure a safe serving from what can be a toxic or even lethal amount.

Who it applies to: Everyone.

Try instead: Do not use pure or powdered caffeine. Get your caffeine from ordinary drinks you can measure. For severe symptoms call your local emergency number; in the US, Poison Help is 1-800-222-1222.

Poisoning: what to do first → Poison Help by country →

Why: The FDA notes caffeine appears in bars, gum, supplements and medicines, and that guarana in energy drinks adds caffeine that should be counted. US adverse event reports and poison centre calls about energy drinks exist (357 and 12,822 single-product cases, 2008 to 2015), but voluntary reports cannot prove the drink caused the problem.

Who it applies to: Anyone who uses energy drinks together with pre-workout, diet or energy supplements.

Try instead: Count every source, avoid doubling up, and see the supplements comparison before buying anything marketed for energy.

Energy supplements compared →

Why: MedlinePlus states that stimulants, including caffeine, are not effective treatments for fatigue and can make the problem worse when they are stopped. Caffeine makes you feel more alert, and can keep you from a good night's sleep, which can feed tomorrow's tiredness.

Who it applies to: Anyone with ongoing tiredness.

Try instead: Look for the cause (sleep, food, stress, health conditions) and see a clinician if tiredness persists.

Fatigue: when to get help →

Why: The FDA says caffeine added to a product behaves like the caffeine in coffee or tea, but in an 18-person trial an energy drink raised QTc more than caffeine alone at 2 hours and systolic pressure more at 6 hours. Another trial of 38 adults found the QTc effect could not be pinned on caffeine, taurine or glucuronolactone alone.

Who it applies to: Regular energy drink users.

Try instead: Treat large energy drinks as a different thing from a cup of coffee, and check the label for caffeine per container.

Why: Decaffeinated coffee still has some caffeine, about 2 to 15 mg in an 8-ounce cup according to the FDA.

Who it applies to: People cutting back, pregnant people, and anyone very sensitive.

Try instead: Count decaf in your total if you are sensitive or have been told to limit caffeine.

Why: Withdrawal headache occurred in about 50 percent of people in experiments, with fatigue, low mood and irritability for 2 to 9 days. The FDA advises cutting back gradually.

Who it applies to: Daily drinkers.

Try instead: Taper in small steps over one to a few weeks and keep water and meals regular.

Why: Caffeine can hide tiredness without treating its cause, and exhaustion lasting weeks may point to something that needs checking, such as poor sleep, anaemia or thyroid problems.

Who it applies to: Anyone tired most days for more than a few weeks.

Try instead: Book a check-up and read about the common causes of tiredness.

Understand & Address Persistent Tiredness → Anemia and iron deficiency →

Why: Late caffeine disturbed sleep in a randomised study, and a narrative review noted caffeine can harm later sleep and cause daytime sleepiness.

Who it applies to: Anyone sleeping badly.

Try instead: Accept a lower-energy day, get daylight and a short walk, and aim for a regular bedtime.

Improve Your Sleep Quality →

Not supported. MedlinePlus states stimulants, including caffeine, are not effective treatments for fatigue and can make it worse when stopped. Caffeine can improve alertness for a while and disturb the next night's sleep.

Not accurate. The FDA cites 400 mg as an amount not generally associated with negative effects for most adults, but stresses wide variation in sensitivity and that some conditions and medicines raise sensitivity. Pregnancy advice in the NHS is 200 mg.

Not supported. 400 mg at bedtime, 3 hours before or 6 hours before habitual bedtime each disturbed sleep in a randomised study compared with placebo.

Not supported. A review of 37 studies reported higher heart rate, blood pressure and QTc in many studies, and small trials saw QTc and blood pressure rises, though effects were short-term and long-term effects were not covered.

Mixed. The AHA statement describes moderate intake, mostly studied as coffee, as linked to no relationship or lower risk of coronary disease, heart failure and stroke, and the DECAF trial found fewer atrial fibrillation recurrences in regular coffee drinkers. These findings do not cover energy drinks, and unfiltered coffee raises LDL cholesterol.

False. Decaffeinated coffee still has about 2 to 15 mg in an 8-ounce cup.