The purpose of this guidance is to advise dietary supplement manufacturers, distributors, and other stakeholders of our intent to exercise enforcement discretion with respect to the sale and distribution of certain products that contain N-acetyl-L-cysteine (NAC) and are labeled as dietary supplements. As described below, the enforcement discretion policy would apply to products that would be lawfully marketed dietary supplements if NAC were not excluded from the definition of “dietary supplement” and that are not otherwise in violation of the Federal Food, Drug, and Cosmetic Act (FD&C Act).