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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 statements are synonymous. Either term or statement may be selected by the applicant.


June 3, 2019

Proper name(s), Common name(s), Source material(s)

Table 1. Proper name(s), Common name(s), Source material(s)
Proper name(s) Common name(s) Source material(s)
Proper name(s) Preparation
  • L-alpha-Acetamido-beta-mercaptopropionic acid
  • N-Acetyl-L-cysteine




References: Proper names: ChemID 2012, Merck 2012; Common name: ChemID 2012; Source ingredient: NHPID 2019.

Route of Administration


Dosage Form(s)

This monograph excludes foods or food-like dosage forms as indicated in the Compendium of Monographs Guidance Document.

Acceptable dosage forms for any age category listed in this monograph for the specified route of administration are listed in the Compendium of Monographs Guidance Document.

Use(s) or Purpose(s)

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



Adults 18 years and older


Not to exceed 600 milligrams of N-Acetyl-L-cysteine, per day (Zembron-Lacny et al. 2009; Zembron-Lacney et al. 2007; Peake and Suzuki 2004; Huupponen et al. 1995).

Direction(s) for use

Take with meals (Quig 1998).

Duration(s) of Use

No statement required

Risk Information

Caution(s) and warning(s)

Consult a health care practitioner/health care provider/health care professional/doctor/physician prior to use if you are pregnant, breastfeeding or have kidney stones (Fauci et al. 1998; Mårtensson et al. 1990).


Do not use this product if you are taking antibiotics or nitroglycerin (Repchinsky 2008; Cederlund and Mårdh 1993; Parry and Neu 1977; Ardissino et al. 1997).

Known adverse reaction(s)

No statement required.

Non-medicinal ingredients

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

Storage conditions

No statement required.


  • The finished product specifications must be established in accordance with the requirements described in the Natural and Non-prescription Health Products Directorate (NNHPD) Quality of Natural Health Products Guide.
  • The medicinal ingredient must comply with the requirements outlined in the NHPID.

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 advanced [Internet]. 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 2019 May 15]. Available from:
  • 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: 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. [Accessed 2019 May 15]. Available from:
  • 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 ?-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.