Caffeine Anhydrous
Also known as: Caffeine, 1,3,7-trimethylxanthine
Methylxanthine alkaloid; non-selective adenosine A1/A2A receptor antagonist; raises cAMP, catecholamine release, and Ca²⁺ sensitivity in muscle.
Last reviewed: 2026-06-23 · 1 indexed study
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Overview
Caffeine anhydrous is the most extensively studied ergogenic aid, antagonising adenosine receptors to reduce perceived effort and improve endurance, strength, and cognitive performance.
Mechanism & Function
Mechanism of Action
Reduces perceived effort, increases motor unit recruitment, mobilises fatty acids, and enhances vigilance/reaction time.
Physiological Role
Robust ergogenic effects across endurance (~3–5% performance), strength (modest), sprint (modest), and cognition (large) at 3–6 mg/kg pre-exercise.
Primary Pathways
Performance / Health Relevance
Hundreds of RCTs and multiple meta-analyses across endurance, strength, sprint, team sport, and cognitive endpoints.
Evidence Review
Practical Use & Dosage
- Minimum Effective Dose
- 100 mg
- Optimal Range
- 3–6 mg/kg 30–60 min pre-exercise
- Upper / Caution Level
- ~9 mg/kg (diminishing returns and side effects)
- Timing
- 30–60 min pre-exercise/task; avoid within 6 h of bed
- Best Format
- Powder, tablet, capsule
- Bioavailability
- ~99% — peak plasma 30–60 min.
- Absorption Considerations
- Rapid passive intestinal absorption.
Safety & Interactions
Side Effects
- •Jitters
- •Insomnia
- •Tachycardia
- •Anxiety
- •GI upset
Contraindications
- Severe anxiety disorders
- Uncontrolled hypertension
- Pregnancy >200 mg/day
Drug Interactions
- •MAOIs
- •Stimulants
- •Clozapine
- •Theophylline
Who Should Avoid
- •Cardiac arrhythmias
- •Severe anxiety
Monitoring
Heart rate, BP in sensitive users.
Frequently Asked Questions
Auto-generated from indexed evidence — dosage, safety, interactions, and more.
When is Caffeine Anhydrous typically used or indicated?
Caffeine Anhydrous is most commonly used for: Energy, Focus, Endurance performance, Strength performance, Fat oxidation. Robust ergogenic effects across endurance (~3–5% performance), strength (modest), sprint (modest), and cognition (large) at 3–6 mg/kg pre-exercise.
How does Caffeine Anhydrous work?
Reduces perceived effort, increases motor unit recruitment, mobilises fatty acids, and enhances vigilance/reaction time.
What is the recommended dose of Caffeine Anhydrous?
The optimal range is 3–6 mg/kg 30–60 min pre-exercise. with a minimum effective dose of 100 mg. Best taken: 30–60 min pre-exercise/task; avoid within 6 h of bed. Upper / caution level: ~9 mg/kg (diminishing returns and side effects).
What are the side effects of Caffeine Anhydrous?
Reported side effects include: Jitters; Insomnia; Tachycardia; Anxiety; and GI upset. Monitoring: Heart rate, BP in sensitive users.
Does Caffeine Anhydrous interact with medications?
Known or theoretical interactions: MAOIs; Stimulants; Clozapine; and Theophylline. Always check with a clinician before combining with prescription medication.
Who should avoid Caffeine Anhydrous?
Caffeine Anhydrous is generally not recommended for: Cardiac arrhythmias; Severe anxiety; Severe anxiety disorders; Uncontrolled hypertension; and Pregnancy >200 mg/day.
How strong is the evidence for Caffeine Anhydrous?
Evidence level: Strong (overall score 90/100), based on 1 indexed study on SuppIndex.
Research & References (1)
Caffeine and exercise performance: international position stand
Robust ergogenic effects; 3–6 mg/kg optimal; individual genetic variation in response.
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Research Overview
Strong EvidenceCite this ingredient
One-click citation export in APA, MLA, Chicago, BibTeX, or HTML. The URL below is stable and safe to link.
Stable URL
https://thesuppindex.com/ingredients/caffeine-anhydrous
SuppIndex. (2026). Caffeine Anhydrous: Evidence summary, dosage and clinical studies. Retrieved October 16, 2026, from https://thesuppindex.com/ingredients/caffeine-anhydrous
Based on 1 indexed studies · Evidence level: Strong.
Goal Ratings
Stack Compatibility
Pairs with L-theanine (smoother focus), beta-alanine (pre-workout), creatine. Cycle to avoid tolerance.