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This monograph is intended to serve as a guide to industry for the preparation of Product Licence Applications (PLAs) and labels for natural health product market authorization. It is not intended to be a comprehensive review of the medicinal ingredient.

  • Text in parentheses is additional optional information which can be included on the PLA and product label at the applicant's discretion.
  • The solidus (/) indicates that the terms and/or the statements are synonymous. Either term or statement may be selected by the applicant.


March 7, 2014

Proper name(s)

  • N-Acetyl-L-Cysteine (ChemID 2012)
  • L-alpha-Acetamido-beta-mercaptopropionic acid (Merck 2012)

Common name(s)

N-Acetyl-L-Cysteine (ChemID 2012)

Source material(s)


Route(s) of administration


Dosage form(s)

  • The acceptable pharmaceutical dosage forms include, but are not limited to capsules, chewables (e.g. gummies, tablets), liquids, powders, strips or tablets.
  • This monograph is not intended to include foods or food-like dosage forms such as bars, chewing gums or beverages.

Use(s) or Purpose(s)

Statement(s) to the effect of:

Provides antioxidants (Zembron-Lacny et al. 2009; Zembron-Lacney et al. 2007; Peake and Suzuki 2004; Huupponen et al. 1995).



Adults (≥ 18 years)


Up to 600 mg N-Acetyl-L-Cysteine, per day (Zembron-Lacny et al. 2009; Zembron-Lacney et al. 2007; Peake and Suzuki 2004; Huupponen et al. 1995).

Directions for use

Take with meals (Quig 1998).

If the ingredient is contained in a protein supplement, the above directions for use is not required.

Duration of use

No statement required.

Risk Information

Statement(s) to the effect of:

Caution(s) and warning(s)

  • If you are pregnant or breastfeeding, consult a health care practitioner prior to use.
  • If you have kidney stones, consult a health care practitioner prior to use (Fauci et al. 1998; Mårtensson et al. 1990).


  • If you are taking antibiotics, do not use this product (Repchinsky 2008; Cederlund and Mårdh 1993; Parry and Neu 1977).
  • If you are taking nitroglycerin, do not use this product (Ardissino et al. 1997).

Known adverse reaction(s)

No statement required.

Non-medicinal Ingredients

Must be chosen from the current NNHPD Natural Health Products Ingredients Database (NHPID) and must meet the limitations outlined in the database.

Storage conditions

No statement required.


References cited

  • Ardissino D, Merlini PA, Savonitto S, Demicheli G, Zanini P, Bertocchi F, Falcone C, Ghio S, Marinoni G, Montemartini C, Mussini A. Effect of transdermal nitroglycerin or N-acetylcysteine, or both, in the long-term treatment of unstable angina pectoris. Journal of the American College of Cardiology 1997;29(5):941-947.
  • Cederlund H, Mårdh PA. Antibacterial activities of non-antibiotic drugs. Journal of Antimicrobial Chemotherapy 1993;32:355-365.
  • ChemID 2012: United States National Library of Medicine. ChemIDplus advancedNext link will take you to another Web site  Acetylcysteine. RN: 616-91-1.Bethesda (MD): Specialized Information Services, United States National Library of Medicine, National Institutes of Health, United States Department of Health & Human Services. [Accessed 2013 August 12].
  • Fauci AS, Braunwald E, Isselbacher KJ, Wilson JD, Martin JB, Kasper DI, Hauser SL and Longo DL, editors. Harrison's Principles of Internal Medicine, 14th edition. Toronto (ON): McGraw-Hill Health Professions Division; 1998.
  • Huupponen MR, Mäkinen LH, Hyvönen PM, Sen CK, Rankinen T, Väisänen S, Rauramaa R. The effect of N-acetylcysteine on exercise-induced priming of human neutrophils. A chemiluminescence study. International Journal of Sports Medicine 1995;16(6):399-403.
  • Mårtensson J, Denneberg T, Lindell å, Textorius O. Sulfur amino acid metabolism in cystinuria : A biochemical and clinical study of patients. Kidney International 1990;37:143-149.
  • Merck 2012: Next link will take you to another Web site The Merck Index Version 14.1. MedicinesComplete - Merck. Whitehouse Station (NJ): Merck & Co., Inc. Copyright © 2006, 2012 Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc. [Published 2006; Updated 2012; Accessed 2013 August 12].
  • Parry MF, Neu HC. Effect of N-acetylcysteine on antibiotic activity and bacterial growth in vitro. Journal of Clinical Microbiology 1977;5(1);58-61
  • Peake J, Suzuki K. Neutrophil activation, antioxidant supplements and exercise-induced oxidative stress. Exercise Immunology Review 2004;10:129-141.
  • Quig D. Cysteine metabolism and metal toxicity. Alternative Medicine Review 1998;3(4):262-270.
  • Repchinsky C, editor. Compendium of Pharmaceuticals and Specialties. The Canadian Drug Reference for Health Professionals. Ottawa (ON): Canadian Pharmacists Association; 2008.
  • Zembron-Lacny A, Slowinska-Lisowska M, Szygula Z, Witkowski K, Szyszka K. The comparison of antioxidant and hematological properties of N-acetylcysteine and a-lipoic acid in physically active males. Physiological Research 2009;58:855-861.
  • Zembron-Lacny A, Szyszka K, Szygula Z. Effect of cysteine derivatives administration in healthy men exposed to intense resistance exercise by evaluation of pro-antioxidant ratio. The Journal of Physiological Sciences 2007;57(6):343-348.

References reviewed

  • De Flora S, Grassi C, Carati L. Attenuation of influenza-like symptomatology and improvement of cell-mediated immunity with long-term N-acetylcysteine treatment. European Respiratory Journal 1997;10(7):1535-1541.
  • Grandjean EM, Berthet P, Ruffmann R, Leuenberger P. Efficacy of oral long-term N-acetylcysteine in chronic bronchopulmonary disease: a meta-analysis of published double-blind, placebo-controlled clinical trials. Clinical Therapeutics 2000;22(2):209-221.
  • Stey C, Steurer J, Bachmann S, Medici TC, Tramer MR.The effect of oral N-acetylcysteine in chronic bronchitis: a quantitative systematic review. European Respiratory Journal 2000;16(2):253-262.