N-Acetylcysteine

    Written by:
    Bill Willis, Katie Jantz

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    Nick Milazzo, Dmitri Barvinok
    Last Updated: September 4, 2025

    N-acetylcysteine (NAC) is a precursor for the amino acid L-cysteine. It has antioxidant, anti-inflammatory, and mucus thinning properties. NAC can act as a direct antioxidant, but more importantly, it provides the cysteine required for the production of glutathione, a powerful antioxidant produced in the body. NAC is commonly taken as a supplement for health and wellness and is used in clinical settings to treat drug overdose, cystic fibrosis, and chronic obstructive pulmonary disease.

    Overview

    Dosage information

    N-acetylcysteine can be given orally, intravenously, topically, or through inhalation.[1] Research suggests that in order to achieve the mucolytic effects in the respiratory tract, NAC can be administered orally or by inhalation.[2] Alternatively, oral or intravenous administration is the best way to benefit from NAC’s antioxidant effects.[3]

    The suggested dosage of NAC depends on what it’s being used for and the route through which it’s being administered. Orally, NAC is most often given in the dosage range of 600–1,800 mg daily (often divided into two or three daily doses), although higher doses are sometimes used in clinical research. Further research is needed to determine the optimal therapeutic dosages for other uses and methods.

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