The FDA declared NAC to be a drug for a few years during COVID
Claude AI NAC in limbo Jan/March? 2026
The core legal issue: The FDA ruled NAC out of the dietary supplement definition under the FD&C Act because it was first approved as a drug on September 14, 1963, before it was ever used in dietary supplements. The FDA is not aware of any evidence that NAC was marketed as a dietary supplement prior to that date.
Current status — enforcement discretion: Since August 2022, the FDA has been exercising enforcement discretion with respect to the sale and distribution of NAC products labeled as dietary supplements — meaning it won't take action against them as long as they're not otherwise in violation of the FD&C Act. This followed significant industry pushback and a lawsuit by the Natural Products Association.
Important caveat: The enforcement discretion does not apply to NAC products labeled as dietary supplements but intended for use in diagnosing, curing, mitigating, treating, or preventing disease — those are still classified as drugs.
What's next — proposed rulemaking: The FDA has been moving toward a formal rule that would permanently resolve NAC's status. The Trump administration's Spring 2025 Unified Agenda indicated FDA plans to publish a proposed rule in January 2026 that would formally allow NAC as a dietary ingredient. However, as of December 2025, that notice of proposed rulemaking had not yet been published.
So the short answer: NAC is still technically excluded from the legal definition of a dietary supplement, but the FDA is looking the other way for now while it works toward a permanent fix through rulemaking. The supplements you'd find on Amazon or in stores are currently in the clear under that enforcement discretion policy.
[NAC Banned on Amazon, Threatened by FDA- June 2021] (https://articles.mercola.com/sites/articles/archive/2021/06/17/nac-banned-on-amazon.aspx?ui=d738e3df52a8a14aea9298fe6ec5bc113ed0d6d7922f31861727d54a43cbe29d&sd;=19000101&cid;source=dnl&cid;medium=email&cid;content=art1HL&cid;=20210617HL2∣=DM912967&rid;=1185497848&p4;=20121119&p5;=) Mercola June 16, 2021
"May 6, 2021, Natural Products Insider reported that Amazon is removing all NAC products from the site, following warning letters being sent out by the FDA stating NAC cannot be lawfully marketed as a dietary supplement because it was first studied as a drug in 1963"
Note; The FDA "documentation" of the 1963 date was handwritten
Article includes many reasons to believe that NAC (N-acetylcysteine) might fight COVID-19
Founder of VitaminDWiki had wondered a week before why the FDA has decided to no longer consider NAC to be a supplement
Suspect that the source of FDA funding did not want to allow a supplement to be important to health
More than half of the FDA entire budget now comes from Big Pharma, not the govt. – Sept 2018
Off Topic: FDA advisors have many conflicts of interest
Earlier in June 2021 the FDA went against all of their advisors and approved an extremely expensive drug for Alzhieimer's
Related in VitaminDWiki
Vitamin D is one of 14 ways proven to treat COVID-19 – July 2021 * COVID-19 treated by Vitamin D - studies, reports, videos *Glutathione is another way to increase GSH - click on tag at the bottom of this page