CaffeineNew
The world's most-used stimulant, studied for alertness, reaction time and exercise performance. Response varies widely with genetics (CYP1A2), habitual intake and timing, and late-day use can erode sleep.
Mechanism of Action
Caffeine blocks adenosine A1 and A2A receptors, reducing perceived fatigue and increasing dopamine and noradrenaline signalling. It also increases catecholamine release and, at higher doses, calcium handling in muscle. It is metabolised mainly by CYP1A2 with a half-life of roughly 5 hours (longer in pregnancy, with oral contraceptives, or liver disease).
Dosing Protocol
200mg per day (3-6 mg/kg acutely for performance; do not exceed about 400 mg/day)
Standard starting dose based on research
Therapeutic Range
50
Minimum
400
Maximum
Morning to early afternoon; stop at least 8 hours before bed. For exercise, about 60 minutes before
Cycling Protocol
Tolerance develops within 1-2 weeks of daily use. Some people cycle off for 1-2 weeks or reserve use for demanding days. Taper over several days to avoid withdrawal headache
Dosages are general guidelines. Individual requirements vary based on body weight, health status, and specific goals. Start with lower doses and adjust based on response.
Benefits
Primary Benefits
- A 2025 network meta-analysis of time-trial performance found low-dose capsules (about 3 mg/kg) gave the largest reduction in completion time (SMD -0.34; 95% CI -0.62 to -0.06), with 4-6 mg/kg as viable alternatives
- A 2025 literature review concluded 3-6 mg/kg is an effective and generally safe ergogenic aid, while noting long-term safety and inter-individual variability need more study
- Short-term improvements in alertness, vigilance and reaction time, especially when sleep-deprived
Secondary Benefits
Safety Information
Contraindications
Do not use if any of the following apply:
- •Pregnancy above about 200-300 mg/day (discuss with a clinician)
- •Uncontrolled hypertension or arrhythmia
- •Anxiety or panic disorder (can worsen symptoms)
- •Insomnia or reflux
- •Seizure disorders (use caution)
- •Children and adolescents (limit intake)
Drug/Supplement Interactions
May interact with the following. Consult a healthcare provider before combining:
Potential Side Effects
Some users may experience:
This is not a complete list of interactions or side effects. Individual responses vary. Always start with the lowest effective dose and monitor your response. Report any adverse effects to your healthcare provider.
Quality Markers
Look for these specific quality indicators when sourcing this compound:
- Label states mg per serving; avoid proprietary blends that hide dose
- Third-party tested for contamination; powdered pure caffeine is dangerous to measure and has caused fatal overdoses
- Single-ingredient capsules or measured coffee/tea for dose control
- No unnecessary stimulant additives
Trusted Certifications
Note: Supplement quality varies dramatically between brands. Cheap supplements often contain fillers, incorrect doses, or contaminants. Investing in quality products from reputable manufacturers is essential for safety and efficacy.
Evidence Profile
Evidence Score
7/10
Moderate Evidence
Some clinical trials with positive results, emerging research
Evidence Scale
8-10
Strong
5-7
Moderate
1-4
Emerging
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