Affiliation: Division of Internal Medicine, Soroka University Medical Center, Ben-Gurion University of the Negev, Beer-Sheva, 84000, Israel.
N-acetylcysteine (NAC), the N-acetyl derivative of the amino acid cysteine, is perhaps best known for its wide use in the treatment of acetaminophen (paracetamol) toxicity, but it has been investigated for the treatment of myriad conditions. In this article we will review the uses of NAC in pulmonary diseases, the mechanism of action dosing, side effect profile and clinical implications in regard to COPD and idiopathic pulmonary fibrosis. One of the main targets of NAC is Inflammation and oxidative stress that are important factors in the pathogenesis of many chronic inflammatory lung disorders. While it is logical to conclude that the administration of antioxidants such as NAC will provide a mode of treatment for said conditions by targeting antioxidant-oxidant imbalance  and although the theory supporting the use of antioxidants is sound, it may not necessarily translate into clinical benefit. Based on the available evidence it is unlikely that mucolytics such as NAC will drastically affect symptoms, exacerbations or disease modification in COPD.