Supplement
Caffeine
SaveThe world's most widely consumed psychoactive substance, a methylxanthine that blocks adenosine receptors to promote wakefulness, focus, and physical performance.
Quick verdict
Unambiguously effective for alertness and exercise performance. Tolerance develops. The most well-studied and cost-effective ergogenic aid available.
Evidence score
A rough internal score reflecting quantity, quality, and consistency of human evidence. Not a clinical recommendation.
What the research shows
Thousands of studies confirm ergogenic, cognitive, and thermogenic effects. ISSN, IOC, and EFSA all recognise performance benefits. Meta-analyses show ~3% improvement in endurance performance and enhanced strength output.
Benefits
- Enhances alertness and reaction time
- Improves endurance and strength performance
- Mild thermogenic effect
Dosage notes
3–6 mg/kg body weight for performance. 100–200 mg for daily alertness. Avoid within 8 hours of bedtime.
Side effects
- Anxiety
- Insomnia
- Tachycardia
- Withdrawal headaches
Who should be cautious
Anxiety, insomnia, and tachycardia at high doses. Genetic variation in CYP1A2 affects metabolism speed. Withdrawal headaches are common.
What this page cannot tell you
Tolerance reduces subjective effects. Half-life of 5–6 hours means afternoon doses impair sleep. Anxiogenic in sensitive individuals.
Leaderboard scores
- Energy85
- Focus82
- Muscle35
Featured in protocols
- Cognitive Performance Stackoptional
- Energy & Endurance Stackoptional
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