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SUPPLEMENT_SCHOLAR
evidence · mechanism · dose
Supplements/Compound

Caffeine

Adenosine antagonist with strong evidence for cognitive and physical performance.

Athletic PerformanceBrain & CognitiveEnergy Production

Overview

Adenosine antagonist with strong evidence for cognitive and physical performance.

Natural sources
  • Coffee
  • Tea
  • Cocoa
  • Yerba mate
Common forms
  • Caffeine anhydrous
  • Coffee
  • Pre-workout

Mechanism of action

Competitive antagonist at adenosine A1/A2A receptors, increasing dopamine and NE.

Pathways
  • · Adenosine antagonism
Neurotransmitters
  • · Dopamine
  • · Norepinephrine

Effects on the body

Increases
Alertness & focus
Increases
Power output & endurance

Organ system effects

Brain & CNS

Improves vigilance and complex attention.

Evidence-based benefits

Improves endurance and power output ~3–6%

Strong evidence

Improves vigilance and reaction time

Strong evidence

Potential side effects

Common
  • · Jitter
  • · Insomnia
  • · Anxiety
Rare
    Serious
    • · Arrhythmia at very high doses (>800 mg acute)

    Drug interactions

    Stimulants
    Additive.
    moderate
    Lithium / clozapine
    Caffeine increases lithium clearance.
    moderate

    Safety & non-supplemental interactions

    Educational summary — always confirm with your clinician or pharmacist before starting, stopping, or combining with prescription therapy.

    Avoid if you are
    • ·Pregnancy — limit to <200 mg/day
    • ·Children/adolescents
    Avoid with these conditions
    • ·Anxiety, panic disorder
    • ·Arrhythmias
    • ·Uncontrolled hypertension
    • ·Insomnia
    • ·GERD
    • ·Interstitial cystitis
    Avoid / monitor with these medications
    • ·MAOIs, stimulants, decongestants
    • ·Ciprofloxacin, fluvoxamine (slow caffeine clearance)
    • ·Lithium (lower levels)
    • ·Clozapine, theophylline
    • ·Hormonal contraceptives (slow clearance)

    Supplement interactions

    Pairs well with
    • L-Theanine
      Smooths jitter, improves focus.
    Avoid combining with

    No specific avoidances listed.

    Dosing & bioavailability

    Typical dose
    3–6 mg/kg pre-workout; ≤400 mg/d
    Timing
    Not within 8h of bedtime

    Where to buy

    Affiliate-style search links to reputable retailers. We don't endorse specific brands — verify third-party testing (USP, NSF, Informed Sport) before purchase.

    Compound
    Caffeine
    Amazon
    Wide selection · fast shipping
    Compound
    Caffeine
    iHerb
    Global delivery · curated brands
    Compound
    Caffeine
    Thorne
    Practitioner-grade · NSF tested

    Scientific evidence (9)

    Meta-analysisBr J Sports Med · 2020

    Caffeine and exercise performance

    Grgic J, et al.

    Umbrella review of caffeine and exercise.

    Key findings

    3–6 mg/kg improves endurance, power, and cognition.

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: Caffeine — Improves endurance and power output ~3–6%

    Live PubMed search

    Live results for "Caffeine Improves endurance and power output ~3–6%" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

    Opens current human and preclinical literature matching Caffeine and "Improves endurance and power output ~3–6%". Filter by RCT, meta-analysis, or year on the results page.

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: Caffeine — Improves vigilance and reaction time

    Live PubMed search

    Live results for "Caffeine Improves vigilance and reaction time" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

    Opens current human and preclinical literature matching Caffeine and "Improves vigilance and reaction time". Filter by RCT, meta-analysis, or year on the results page.

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: Caffeine — randomized controlled trial

    Live PubMed search

    Live results for "Caffeine randomized controlled trial" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

    Opens current human and preclinical literature matching Caffeine and "randomized controlled trial". Filter by RCT, meta-analysis, or year on the results page.

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: Caffeine — meta-analysis

    Live PubMed search

    Live results for "Caffeine meta-analysis" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

    Opens current human and preclinical literature matching Caffeine and "meta-analysis". Filter by RCT, meta-analysis, or year on the results page.

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: Caffeine — pharmacokinetics

    Live PubMed search

    Live results for "Caffeine pharmacokinetics" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

    Opens current human and preclinical literature matching Caffeine and "pharmacokinetics". Filter by RCT, meta-analysis, or year on the results page.

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: Caffeine — safety adverse events

    Live PubMed search

    Live results for "Caffeine safety adverse events" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

    Opens current human and preclinical literature matching Caffeine and "safety adverse events". Filter by RCT, meta-analysis, or year on the results page.

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: Caffeine — dose response

    Live PubMed search

    Live results for "Caffeine dose response" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

    Opens current human and preclinical literature matching Caffeine and "dose response". Filter by RCT, meta-analysis, or year on the results page.

    Open study
    Systematic reviewGoogle Scholar · 1970

    Google Scholar: Caffeine — clinical evidence

    Live Scholar search

    Cross-database citation index for Caffeine as it relates to "clinical evidence".

    Key findings

    Includes preprints, theses, and journal articles. Useful for tracking citation counts and follow-on work.

    Open study
    Educational use only. This profile is not medical advice. Consult a qualified healthcare professional before starting any supplement, especially if you take prescription medication or have a chronic condition.