On November 24, 2021, The Food and Drug Administration (FDA) is requesting information on the past use of N-acetyl-L-cysteine (NAC) in products marketed as dietary supplements.

Earlier this year, the FDA received two citizen petitions asking the agency to reconsider its position on the use of NAC as a dietary supplement. In June 2021, the Council for Responsible Nutrition (CRN) asked the FDA to reverse the agency’s position that NAC-containing products cannot be dietary supplements. In August 2021, the Natural Products Association (NPA) asked the FDA to either determine that NAC is not excluded from the definition of a dietary supplement or, in the alternative, initiate rulemaking to make NAC a lawful dietary supplement under the Federal Food, Drug, and Cosmetic Act.

Today, the FDA issued tentative responses to both citizen petitions, requesting additional information from the petitioners and interested parties and noting that the agency needs additional time to carefully and thoroughly review the complex questions posed in these petitions.

To help the agency respond to the petitions, the FDA is interested in receiving data and information on the earliest date that NAC was marketed as a dietary supplement or as a food, the safe use of NAC in products marketed as a dietary supplement, and any safety concerns. If applicable, the FDA will use the information submitted to the public docket and other applicable information to determine if rulemaking to make NAC lawful as a dietary supplement is appropriate.

The FDA is asking interested parties to submit such information by January 25, 2022, while the agency continues to evaluate both citizen petitions. The agency will use the information submitted for our analysis and provide a final response to both petitioners directly once we complete our review.