Sports and energy
Caffeine
Also called: caffeine pills, caffeine anhydrous
The stimulant in coffee and tea, in tablet form.
- Why people take it
- Alertness, exercise performance.
- What the evidence says
- Good evidence for improving endurance and alertness.
- How it is usually taken
- Usually 3 to 6 mg per kg of body weight about an hour before exercise; most adults should stay under 400 mg a day.
- Be careful
- Adults should keep under about 400 mg a day (200 mg in pregnancy). Pure caffeine powders have caused deaths; never use them.
- Medicines it can interact with
- Ciprofloxacin, fluvoxamine and the contraceptive pill raise caffeine levels; adds to stimulants, theophylline and decongestants.
Other sports and energy
Common questions
What is Caffeine?
The stimulant in coffee and tea, in tablet form.
Why do people take Caffeine?
Alertness, exercise performance.
Does Caffeine work?
Good evidence for improving endurance and alertness.
How much Caffeine do people take?
Usually 3 to 6 mg per kg of body weight about an hour before exercise; most adults should stay under 400 mg a day.
Is Caffeine safe?
Adults should keep under about 400 mg a day (200 mg in pregnancy). Pure caffeine powders have caused deaths; never use them.
Does Caffeine interact with medicines?
Ciprofloxacin, fluvoxamine and the contraceptive pill raise caffeine levels; adds to stimulants, theophylline and decongestants.
Sources and further reading
Last reviewed 31 October 2026. Written by Satya Babu.
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