Why Was NMN Banned? The FDA Ruling Explained

The Bottom Line First

If you have seen headlines saying NMN was banned, or if you noticed NMN disappear from Amazon between late 2022 and 2025, the situation deserves a clear explanation. The confusion arose from a specific regulatory clause in US food and drug law that was applied in an unusual way, and then reversed.

NMN was never found to be unsafe. The FDA never issued a warning about NMN's health profile. No human clinical trial reported a safety signal that prompted regulatory action. The compound's removal from mainstream retail was entirely a legal regulatory matter, and that matter has now been resolved in favour of NMN's lawful supplement status.

The Drug Preclusion Clause: How It Works

To understand what happened, you need to understand one provision in the Food, Drug and Cosmetic Act (FD&C Act). Section 201(ff)(3)(B) states that a substance cannot be marketed as a dietary supplement if it was the subject of substantial clinical investigations as a new drug that were authorised and made public before the substance was lawfully marketed as a dietary supplement in the US. This is known as the drug preclusion clause.

The practical intent of this clause is to prevent supplement companies from selling something as a supplement after a pharmaceutical company has invested heavily in developing it as a regulated drug. The policy logic is to protect the pharmaceutical development pathway from being undermined by supplement marketing of the same substance. The clause creates a one-way door: if a substance is first investigated as a drug, it cannot then be sold as a supplement.

The problem for NMN was that a pharmaceutical company called Metro International Biotech developed a proprietary NMN formulation called MIB-626 and obtained an Investigational New Drug authorisation from the FDA, then notified the FDA of this. Once the FDA became aware of this notification, it concluded in November 2022 that the drug preclusion clause applied to NMN and issued a letter stating NMN was excluded from the definition of a dietary supplement.

November 2022: The FDA Letter and Market Disruption

The FDA's November 2022 letter had immediate and widespread market consequences. Amazon, responding to the regulatory position as major retailers typically do when the FDA issues such a determination, removed NMN products from its platform. Other large US retailers followed. The announcement caused significant confusion because it appeared to consumers as if NMN had been banned or found dangerous, when in fact the action was a legal technicality with no safety basis.

For existing NMN manufacturers and distributors, the letter created genuine uncertainty. US-based companies that had been selling NMN legally faced unclear guidance on whether they could continue. International manufacturers who supplied US customers faced a disrupted market. Consumers who had been taking NMN daily suddenly found their supply unavailable through mainstream channels.

NMN products did not disappear entirely. Many companies continued to sell NMN, some directly to consumers through their own websites and some through channels that operated during the enforcement uncertainty period. But the mainstream retail availability was significantly reduced for almost three years.

The Industry Response: Citizens Petition and Federal Lawsuit

The Natural Products Association (NPA), a major US dietary supplement industry trade group, refused to accept the FDA's 2022 interpretation. They were joined by the Alliance for Natural Health USA (ANH). On March 7, 2023, NPA and ANH filed a joint citizen petition with the FDA requesting that the agency determine NMN was not excluded from the dietary supplement definition, or commit to a policy of enforcement discretion while the matter was reviewed.

The FDA acknowledged the petition but in September 2023 stated it had been unable to reach a decision due to competing agency priorities. This effectively left the industry in regulatory limbo for another year.

In August 2024, NPA escalated by filing a federal lawsuit against the FDA in Washington, D.C. federal court. The NPA's core legal argument was that the drug preclusion clause contains a race-to-market exception: if a substance was marketed as a dietary supplement in the US before it was authorised as an investigational drug, the preclusion does not apply. NPA presented evidence that NMN had been sold as a dietary supplement in the United States as early as 2017. Metro International Biotech's IND authorisation came later. Under the race-to-market provision, the drug preclusion clause simply should not have applied to NMN at all.

In late 2024, a federal court granted a stay of the lawsuit to allow the FDA time to evaluate the citizen petition. During the stay, the FDA also adopted a period of enforcement discretion regarding NMN products, providing interim relief to the industry.

September 29, 2025: The FDA Reversal

On September 29, 2025, the FDA issued two letters reversing its 2022 position. In these letters, the principal deputy director for human foods confirmed that NMN is not excluded from the definition of a dietary supplement. The FDA's stated reasoning centred on the race-to-market provision: the agency acknowledged evidence that NMN was marketed as a dietary supplement in the United States before it was authorised for investigation as a new drug, meaning the drug preclusion clause did not apply under the law's own terms.

The FDA's letter stated directly: "We now conclude that NMN is not excluded from the definition of dietary supplement under section 201(ff)(3)(B). Specifically, although NMN was authorized for investigation as a new drug, and substantial clinical investigations of NMN have been instituted and made public, NMN was marketed as a dietary supplement in the United States before such authorization."

Following the September 2025 reversal, NPA filed to voluntarily dismiss its federal lawsuit. In December 2025, the FDA issued additional letters to specific NMN ingredient suppliers, reinstating New Dietary Ingredient notification responses and providing further regulatory clarity to the supply chain.

Why This Was Never a Safety Issue

Throughout the entire regulatory controversy, from November 2022 through September 2025, the FDA never issued any statement suggesting NMN was unsafe. No safety recall was issued. No adverse event data prompted the action. The agency's position was entirely about the legal definition of a dietary supplement under DSHEA and the drug preclusion clause, not about NMN's safety profile.

This matters for anyone who was concerned that the removal of NMN from mainstream retail reflected newly discovered health risks. It did not. The human clinical trial evidence supporting NMN's safety, accumulated across more than a dozen completed trials at doses up to 1250 mg daily, remained consistent throughout this period. The compound was the same compound, with the same safety record, before and after the regulatory dispute.

The confusion arose partly because consumers and media interpreted the FDA's position as a safety-based action rather than a regulatory technicality. Regulatory language is opaque, and the drug preclusion clause is not a concept most consumers encounter in daily life. The headline "FDA says NMN cannot be sold as a supplement" reads very differently from the more accurate "FDA applied a legal technicality incorrectly and has since reversed it."

What This Means for Solensis and US Consumers

Solensis NMN Powder is manufactured in the United States in a GMP-certified, FDA-regulated facility, independently tested by Adamson Analytical Laboratories (Corona, CA), and compliant with the current regulatory status of NMN as a lawful dietary ingredient. The FDA's September 2025 reversal confirms what was always the case from a scientific standpoint: NMN is a naturally occurring molecule with a strong safety profile and a growing body of human clinical trial evidence, and it belongs in the dietary supplement category.

The broader regulatory lesson from the NMN case is about supply chain quality rather than safety. The controversy highlighted the importance of sourcing NMN from US-regulated manufacturers with proper documentation, independent third-party testing, and verifiable Good Manufacturing Practice certification. Products assembled from unverified raw materials may have entered the market during the enforcement uncertainty period. The case for third-party verified purity at 98% or above from a named, accredited laboratory is stronger now than before the controversy.

The Broader Problem: Drug Preclusion and Supplement Innovation

The NMN case is not the first time the drug preclusion clause has created controversy. A similar situation arose with NAC (N-acetyl-L-cysteine), another popular supplement ingredient, which the FDA attempted to exclude from the dietary supplement category for similar drug development reasons. In that case too, the NPA successfully challenged the FDA's interpretation, and the agency ultimately issued guidance allowing NAC products to remain on the market.

The pattern raises a legitimate policy concern: the drug preclusion clause as currently interpreted creates a mechanism by which pharmaceutical companies can potentially prevent or disrupt supplement competition for ingredients that are naturally occurring or have long histories of safe use. If a company files an IND application for a natural compound that is already widely available as a supplement, the FDA's current (pre-September 2025) interpretation could have been used to remove that supplement from the market.

The NPA has indicated it will continue to work with Congress on a legislative fix to the drug preclusion clause to prevent similar situations arising for other supplement ingredients in future. The NMN case has, in the NPA's words, provided more clarity on the drug preclusion clause than ever before, which may benefit the broader supplement industry going forward.

Frequently Asked Questions

Is NMN banned in the USA?

No. As of September 29, 2025, the FDA confirmed NMN is lawful for use in dietary supplements in the United States. The 2022 exclusion was a regulatory technicality, not a safety finding, and it has been fully reversed. NMN can be legally purchased from US-based manufacturers and retailers.

Why did the FDA ban NMN?

The FDA did not ban NMN for safety reasons. In November 2022, it applied the drug preclusion clause in the FD&C Act after a pharmaceutical company filed an Investigational New Drug application for a proprietary NMN compound. The FDA concluded NMN was excluded from the dietary supplement definition. This was a legal interpretation, not a safety or health concern. The FDA reversed this position in September 2025.

When was NMN made legal again?

September 29, 2025. The FDA issued letters on that date confirming NMN is not excluded from the dietary supplement definition, reversing its November 2022 position. The reversal followed a successful citizen petition and federal lawsuit by the Natural Products Association, which demonstrated NMN had been marketed as a dietary supplement in the US since at least 2017.

Was NMN banned because it is dangerous?

No. The 2022 exclusion was purely a regulatory interpretation of the drug preclusion clause, with no basis in safety data. Multiple completed human clinical trials confirmed NMN's safety throughout this period. The FDA never issued a safety warning about NMN. The exclusion was a legal technicality that has since been corrected.

Why was NMN removed from Amazon?

Amazon removed NMN following the FDA's November 2022 letter stating NMN was excluded from the dietary supplement definition. Major retailers typically comply with FDA enforcement positions to avoid regulatory risk. Following the FDA's September 2025 reversal, NMN returned to Amazon and other mainstream retailers.

Is NMN legal to buy now?

Yes. As of September 29, 2025, the FDA confirmed NMN is lawful in US dietary supplements. Consumers can legally purchase NMN from US-based manufacturers. NMN remains classified as a New Dietary Ingredient, so manufacturers must comply with NDIN requirements, but the drug preclusion exclusion no longer applies.

What is the drug preclusion clause and why did it affect NMN?

The drug preclusion clause (FD&C Act section 201(ff)(3)(B)) prevents a substance from being marketed as a dietary supplement if it was first investigated as a new drug through authorised substantial clinical investigations. Metro International Biotech filed an IND application for a proprietary NMN compound, which the FDA claimed triggered this clause for NMN broadly. The NPA successfully argued the race-to-market exception: NMN had been sold as a supplement since 2017, before the drug investigation, so the preclusion should never have applied.