Caffeine and energy drinks: Effect, amounts and risks

In short: Caffeine makes you more awake in the short term but can burden sleep, heart and nerves; for adults about 400 mg a day is considered safe, for teenagers and pregnant women less.

In more detail: Caffeine is found in coffee, tea, cola, energy drinks, chocolate and some medicines. It blocks receptors for adenosine, a substance that makes you tired. So you feel more awake. This is general information and does not replace medical advice. With complaints, illnesses, pregnancy or medication, ask a doctor or pharmacist.

In Depth

Typical contents (approximate)

• Espresso (30 ml): 60 to 80 mg.
• Filter coffee (200 ml): 80 to 120 mg.
• Black tea (200 ml): 30 to 50 mg.
• Cola (330 ml): 30 to 40 mg.
• Energy drink (250 ml): about 80 mg, some 500 ml cans accordingly 160 mg; additionally taurine, sugar, often sweeteners.
• Dark chocolate (100 g): 20 to 50 mg. On packaging a warning appears for high caffeine content (“high caffeine content, not recommended for children and pregnant women”).

Recommendations

The European Food Safety Authority (EFSA) regards up to about 400 mg per day (about four cups of coffee) and 200 mg at once as safe for healthy adults, for pregnant women about 200 mg a day. For children and adolescents a guide value is about 3 mg per kg body weight; energy drinks are not advisable for them, and sales to minors are restricted or debated in many countries.

Effects and risks

Too much caffeine can lead to restlessness, palpitations, tremor, stomach complaints, sleep disorders and anxiety. It acts for several hours (half-life about 5 hours), so avoid it in the afternoon and evening. Mixing with alcohol masks tiredness and raises risk. Regular consumption leads to habituation; sudden abstinence often brings headaches. Those with heart problems, high blood pressure, anxiety disorders should be careful.

Alternatives and habits

Better against tiredness: sleep, exercise, daylight, water, regular breaks. If you drink coffee: not in excess on an empty stomach, combine with water, the last coffee at the latest in the early afternoon. Study days benefit more from breaks and sleep than from energy drinks. Mind sugar traps: many energy and coffee drinks contain many calories.

See also: Hidden sugar, Sweeteners, Reading the nutrition table, Learning how to learn