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    Amino AcidsSemi-Synthetic

    NAC (N-Acetyl Cysteine)

    Also known as: N-Acetylcysteine, NAC

    Acetylated cysteine deacetylated in the gut/liver to L-cysteine, the rate-limiting substrate for glutathione (GSH) synthesis; also has direct thiol antioxidant activity.

    Last reviewed: 2026-06-23 · 1 indexed study

    Evidence Score
    72/100
    Glutathione supportLiver healthAntioxidantRespiratory supportMental health
    Data Completeness3/4 · 75%
    Evidence ScoreDosageSafetyLinked Studies

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    Overview

    N-Acetyl Cysteine (NAC) is a cysteine prodrug that replenishes intracellular glutathione, supports liver detoxification, and has emerging evidence in respiratory and psychiatric applications.

    Mechanism & Function

    Mechanism of Action

    Replenishes hepatic and systemic GSH pools, supports phase II conjugation, breaks disulfide bonds in mucus (mucolytic), and modulates glutamatergic neurotransmission.

    Physiological Role

    Used in heavy training blocks for oxidative stress, in athletes with high alcohol or paracetamol exposure, and in respiratory health (chronic bronchitis).

    Primary Pathways

    Glutathione synthesisDirect thiol antioxidantMucolytic activityGlutamate modulation

    Performance / Health Relevance

    Robust evidence as paracetamol antidote and mucolytic; strong evidence in OCD/trichotillomania; modest evidence in athletic oxidative stress.

    Evidence Review

    Overall72/100
    Human Clinical78/100
    Meta-Analysis72/100
    Mechanistic86/100
    Real-World68/100
    Safety85/100

    Practical Use & Dosage

    Minimum Effective Dose
    600 mg/day
    Optimal Range
    600–1800 mg/day in divided doses
    Upper / Caution Level
    ~2400 mg/day
    Timing
    With food (sulfur odour)
    Best Format
    Capsule, effervescent powder
    Bioavailability
    ~10% oral bioavailability of intact NAC, but cysteine release is high.
    Absorption Considerations
    Rapid deacetylation in gut/liver releases cysteine for GSH synthesis.

    Safety & Interactions

    Side Effects

    • •Sulfur odour
    • •Mild GI upset
    • •Rare bronchospasm in asthmatics with inhaled

    Contraindications

    • Asthma exacerbation history (caution)

    Drug Interactions

    • •Nitroglycerin
    • •Activated charcoal

    Who Should Avoid

    • •Active peptic ulcer

    Monitoring

    None routine.

    Frequently Asked Questions

    Auto-generated from indexed evidence — dosage, safety, interactions, and more.

    When is NAC (N-Acetyl Cysteine) typically used or indicated?

    NAC (N-Acetyl Cysteine) is most commonly used for: Glutathione support, Liver health, Antioxidant, Respiratory support, Mental health. Used in heavy training blocks for oxidative stress, in athletes with high alcohol or paracetamol exposure, and in respiratory health (chronic bronchitis).

    How does NAC (N-Acetyl Cysteine) work?

    Replenishes hepatic and systemic GSH pools, supports phase II conjugation, breaks disulfide bonds in mucus (mucolytic), and modulates glutamatergic neurotransmission.

    What is the recommended dose of NAC (N-Acetyl Cysteine)?

    The optimal range is 600–1800 mg/day in divided doses. with a minimum effective dose of 600 mg/day. Best taken: With food (sulfur odour). Upper / caution level: ~2400 mg/day.

    What are the side effects of NAC (N-Acetyl Cysteine)?

    Reported side effects include: Sulfur odour; Mild GI upset; and Rare bronchospasm in asthmatics with inhaled. Monitoring: None routine.

    Does NAC (N-Acetyl Cysteine) interact with medications?

    Known or theoretical interactions: Nitroglycerin; and Activated charcoal. Always check with a clinician before combining with prescription medication.

    Who should avoid NAC (N-Acetyl Cysteine)?

    NAC (N-Acetyl Cysteine) is generally not recommended for: Active peptic ulcer; and Asthma exacerbation history (caution).

    How strong is the evidence for NAC (N-Acetyl Cysteine)?

    Evidence level: Moderate (overall score 72/100), based on 1 indexed study on SuppIndex.

    Research & References (1)

    NAC for psychiatric and neurological disorders: meta-analysis

    Meta-Analysis2018Moderate
    PubMed

    Significant benefit in OCD, trichotillomania, and adjunct depression treatment.

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    Research Overview

    Moderate Evidence
    1Total Studies
    0Human Trials
    1Meta-Analyses
    2018Latest Study
    0Animal / In Vitro
    0Athlete Studies
    Primary data sourceMixed
    Pooled evidence (meta-analysis / systematic review)Yes

    Cite 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/nac

    SuppIndex. (2026). NAC (N-Acetyl Cysteine): Evidence summary, dosage and clinical studies. Retrieved October 16, 2026, from https://thesuppindex.com/ingredients/nac

    Based on 1 indexed studies · Evidence level: Moderate.

    Goal Ratings

    General Health
    Recovery
    Stress

    Stack Compatibility

    Pair with vitamin C, glycine, and selenium for antioxidant network.

    Vitamin CGlycineSelenium