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Caffeine (supplement form)
What Caffeine (supplement form) is, what the NIH ODS fact sheet says the evidence supports, typical doses, timing, and the cautions that come with it.
Supplements are not medicines and this page is not medical advice. Doses that help one person can harm another — with medicines, kidney or liver conditions, pregnancy, or before surgery, talk to a clinician before starting anything. More is not better.
What it is
The stimulant from coffee, tea and many pre-workouts.
What the evidence supports
ODS (exercise performance fact sheet): improves endurance and strength performance in many studies at 3-6 mg per kg taken before exercise.
Dose and timing
Studied performance dose: about 3-6 mg per kg of body weight. About 45-60 minutes before exercise.
Cautions
Up to 400 mg per day is considered safe for most healthy adults (EFSA); late-day caffeine trades tonight's sleep for today's alertness.
Interactions are the hidden risk: supplements can change how medicines work and vice versa. Give your clinician the full list before anything else.
Source: NIH Office of Dietary Supplements — Caffeine (supplement form) fact sheet · checked 2026-09-03
Frequently asked questions
What does Caffeine (supplement form) do?
The stimulant from coffee, tea and many pre-workouts.
Does Caffeine (supplement form) work?
ODS (exercise performance fact sheet): improves endurance and strength performance in many studies at 3-6 mg per kg taken before exercise.
How much caffeine (supplement form) should I take?
Studied performance dose: about 3-6 mg per kg of body weight. About 45-60 minutes before exercise.
Is Caffeine (supplement form) safe?
Up to 400 mg per day is considered safe for most healthy adults (EFSA); late-day caffeine trades tonight's sleep for today's alertness. And the standing rule: tell your clinician everything you take — supplements interact with medicines.
Creatine
Studied doses: 3-5 g per day; loading protocols use about 20 g/day in 4 doses for 5-7 days.
Magnesium
RDA: men 400-420 mg, women 310-320 mg per day.
Vitamin D
RDA: 600 IU (15 mcg) to age 70, then 800 IU (20 mcg). UL 4000 IU.
Omega-3s (EPA/DHA)
No RDA for EPA/DHA; ALA: men 1.6 g, women 1.1 g per day. Many products supply 250-500 mg combined EPA+DHA per day.
Melatonin
Studied doses commonly 0.5-5 mg, taken 30-60 minutes before bed.
Iron
RDA: men 8 mg, women 19-50 18 mg, pregnancy 27 mg per day.
Log it, and show it to your doctor
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