Skip to main content
Supplement ScienceSupplementScience

NAC (N-Acetyl Cysteine) Side Effects & Safety

Evidence:Strong
·

This content is for informational purposes only and does not constitute medical advice. Statements about dietary supplements have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease. Individual results may vary — consult your healthcare provider before starting any supplement. Full disclaimer

Safety Profile

Overall safety rating: Generally Safe

Potential Side Effects

  • GI discomfort (nausea, vomiting, diarrhea) — the most common side effect
  • Sulfurous smell and taste
  • Rare headache
  • May increase urinary zinc excretion — consider zinc supplementation with long-term use

Drug & Supplement Interactions

  • Nitroglycerin — NAC may potentiate vasodilatory effects; headache and hypotension risk
  • Activated charcoal — may reduce NAC absorption
  • Chemotherapy — consult oncologist (antioxidant concerns)
  • Zinc — NAC may increase zinc excretion; supplement zinc if using long-term

Maximum Dose

Do not exceed: 2,400 mg/day is commonly used in psychiatric trials; higher doses used under medical supervision

Looking for a well-tested NAC (N-Acetyl Cysteine)?
All our top picks are third-party verified for purity
Full NAC (N-Acetyl Cysteine) Guide

References

  1. RCTGrant JE, Odlaug BL, Kim SW (2009). N-acetylcysteine, a glutamate modulator, in the treatment of trichotillomania: a double-blind, placebo-controlled study. Archives of General Psychiatry. DOI PubMed
  2. ReviewRushworth GF, Megson IL (2014). Existing and potential therapeutic uses for N-acetylcysteine: the need for conversion to intracellular glutathione for antioxidant benefits. Pharmacology & Therapeutics. DOI PubMed
  3. Meta-analysisViña I, Viña JR, Carranza M, Mariscal G (2025). Efficacy of N-Acetylcysteine in Polycystic Ovary Syndrome: Systematic Review and Meta-Analysis.. Nutrients. DOI PubMed
  4. Meta-analysisPapi A, Alfano F, Bigoni T, Mancini L, et al. (2024). N-acetylcysteine Treatment in Chronic Obstructive Pulmonary Disease (COPD) and Chronic Bronchitis/Pre-COPD: Distinct Meta-analyses.. Archivos de bronconeumologia. DOI PubMed
  5. Winterlind EL, Malone SG, Setzer MR, Murphy MA, et al. (2024). N-acetylcysteine as a treatment for substance use cravings: A meta-analysis.. Addiction biology. DOI PubMed
  6. Meta-analysisPeng TR, Lin HH, Tseng TL, Huang YH, et al. (2024). Efficacy of N-acetylcysteine for patients with depression: An updated systematic review and meta-analysis.. General hospital psychiatry. DOI PubMed
  7. Koh A, Wong T, Adiamah A, Sanyal S (2024). Systematic review and meta-analysis of the effect of N-acetylcysteine on outcomes after liver resection.. ANZ journal of surgery. DOI PubMed
Show 3 more references
  1. Huang C, Kuo S, Lin L, Yang Y (2023). The efficacy of N-acetylcysteine in chronic obstructive pulmonary disease patients: a meta-analysis.. Therapeutic advances in respiratory disease. DOI PubMed
  2. Kishi T, Sakuma K, Hatano M, Iwata N (2023). N-acetylcysteine for schizophrenia: A systematic review and meta-analysis.. Psychiatry and clinical neurosciences. DOI PubMed
  3. Nejati M, Dehghan P, Jamilian P, Zarezadeh M (2022). The effects of N-acetylcysteine on recovery biomarkers: A systematic review and meta-analysis of controlled trials.. Journal of food biochemistry. DOI PubMed