N-Acetylcysteine (NAC) has several indications and can be used in respiratory medicine [chronic obstructive pulmonary disease (COPD), interstitial lung diseases such as idiopathic pulmonary fibrosis (IPF), bronchiectasis, and influenza], and has been used worldwide for over 50 years.

When treatment requires chronic use, as in COPD and cystic fibrosis, the maximum licensed dose is 600 mg/day, but doses > 600 mg daily have been studied in some clinical trials.

Studies of high doses of NAC (up to 3000 mg/day) in respiratory diseases with explicit reports on safety found that NAC was safe and well tolerated. In general, the safety profile is similar at both the high and standard doses.