What is it used for?
Source of (an) antioxidant(s)/Provides (an) antioxidant(s) [Source note 2].
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 [Source note 3].
Note: If N-Acetyl-L-cysteine is combined with other active 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 active ingredient associated with the antioxidant claim.
Who does this guide cover?
Adults 18 years and older
How is it taken?
Oral
Which forms are covered?
this reference excludes foods or food-like dosage forms as indicated in the Compendium of references Guidance Document.
Quantities
Not to exceed 600 milligrams of N-Acetyl-L-cysteine, per day [Source note 4].
How is it used?
Take with a meal [Source note 5].
How long is it used?
The reference does not require an additional label statement in this section. This does not establish an absence of risk.
Warnings and precautions
Ask a healthcare professional before use if you are pregnant or breastfeeding.
Ask a healthcare professional before use if you have kidney stones [Source note 6].
When should it be avoided?
Do not use if you are taking antibiotics or nitroglycerin [Source note 7].
Possible side effects
The reference does not require an additional label statement in this section. This does not establish an absence of risk.
Storage
Must be established in accordance with the requirements described in the applicable product regulations.
Preparation details
Ingredient identity, preparation requirements, and other details that define the scope of this guide.
Ingredients and preparations
| Proper name(s) | Common name(s) | Source information / Source ingredient(s) | Source information / Preparation(s) |
|---|---|---|---|
| N-Acetyl-L-cysteine | N-Acetyl-L-cysteine | Synthetic |
References: Proper names: NIH 2024; RSC 2024; Common name: NIH 2024; Source information: NIH 2024.
Other ingredients
Must be chosen from the current source ingredient database and must meet the limitations outlined in the database.
Preparation and quality requirements
The finished product specifications must be established in accordance with the requirements described in the source authority source’s product quality guidance.
The active ingredient must comply with the requirements outlined in the source ingredient database.
Guide change history
Updates to this SupplementSafety.org guide.
Minor updates
Updated guide wording, organization, and source presentation. Added our editorial change history.
Initial release
Initial SupplementSafety.org guide prepared from source reference material.
Validation: Not yet completed. Editorial updates do not constitute clinical validation.
Sources
Source information
This guide organizes source material about uses, preparations, amounts, and precautions. Read the conditions alongside each statement; the information may apply only to particular preparations or populations.
The source document includes supporting references. We have not independently summarized or assessed every cited study for this guide.
- Source document version
- December 19, 2025
- Source captured
- Aug 15, 2026
- Editorial work
- Editorial preparation. Independent clinical review has not been recorded for this guide.
Full citations are available through the link above. Verification is required to open them; reading this guide does not require verification.
Taking a medication too?
Explore our supplement–medication interaction checker. Its coverage and review status are shown with the results; a missing finding does not establish that a combination is safe.