N-ACETYL-L-CYSTEINE

Monograph: N-ACETYL-L-CYSTEINE (PDF Version - 78 KB)

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.

Notes

  • Text in parentheses is additional optional information which can be included on the label at the applicant's discretion.
  • The solidus (/) indicates that either term and/or statement may be selected on the label.

Date

December 19, 2025

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

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

References: Proper names: NIH 2024; RSC 2024; Common name: NIH 2024; Source information: NIH 2024.

Route(s) of Administration

Oral

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 oral use are indicated in the dosage form drop-down list of the web-based Product Licence Application form for Compendial applications.

Use(s) or Purpose(s)

  • Source of (an) antioxidant(s)/Provides (an) antioxidant(s) (Zembron-Lacny et al. 2009; Zembron-Lacney et al. 2007; Peake and Suzuki 2004; Huupponen et al. 1995).
  • Source of (an) antioxidant(s)/Provides (an) antioxidant(s) that help(s) fight/protect (cell) against/reduce (the oxidative effect of/the oxidative damage caused by/cell damage caused by) free radicals (Zembron-Lacny et al. 2009; Zembron-Lacney et al. 2007; Peake and Suzuki 2004; Huupponen et al. 1995).

Note: If N-Acetyl-L-cysteine is combined with other medicinal ingredients with antioxidant properties, there is an option to use the antioxidant claims in plural. The singular should be used when the product only contains one chemical substance (e.g., N-Acetyl-L-cysteine) as the medicinal ingredient associated with the antioxidant claim.

Dose(s)

Subpopulation(s)

Adults 18 years and older

Quantity(ies)

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 a meal (Quig 1998).

Duration(s) of use

No statement required

Risk information

Caution(s) and warning(s)

Ask a health care practitioner/health care provider/health care professional/doctor/physician before use if you are pregnant or breastfeeding.

Ask a health care practitioner/health care provider/health care professional/doctor/physician before use if you have kidney stones (Fauci et al. 1998; Mårtensson et al. 1990).

Contraindication(s)

Do not use if you are taking antibiotics or nitroglycerin (Repchinsky 2008; Cederlund and Märdh 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

Must be established in accordance with the requirements described in the Natural Health Products Regulations.

Specifications

  • 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.

EXAMPLE OF PRODUCT FACTS:

Consult the Guidance Document, Labelling of Natural Health Products for more details.

Product Facts Table

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, Märdh PA. Antibacterial activities of non-antibiotic drugs. Journal of Antimicrobial Chemotherapy 1993;32:355-365.
  • 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.
  • NIH 2024: National Institutes of Health. PubChem. Bethesda (MD): National Library of Medicine, US Department of Health & Human Services. [Accessed 2024 October 23]. Available from: https://pubchem.ncbi.nlm.nih.gov/
  • 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.
  • RSC 2024: Royal Society of Chemistry: The Merck Index Online [Accessed 2024 November 26]. Available from: https://merckindex.rsc.org/
  • Zembron-Lacny A, Slowinska-Lisowska M, Szygula Z, Witkowski K, Szyszka K. The comparison of antioxidant and hematological properties of N-acetylcysteine and α-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.

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