What FDA's 1 September peptide warning letters cite
On 1 September 2026 FDA posted four warning letters to peptide sellers, each issued by the Center for Drug Evaluation and Research on 24 August 2026 and each charging unapproved new drugs and misbranding under sections 301(d) and 505(a) of the FD&C Act. The recipients were TXP Innovations LLC dba Tex Peptides (MARCS-CMS 735067), Royal Peptides LLC (734884), NuScience Peptides LLC (733652) and Peptide Partners LLC (735063). The charges themselves are not new; FDA has issued materially similar letters throughout 2026. What is worth reading closely is the evidence the agency assembled, because in all four letters it extends past product descriptions to the rest of the storefront.
What did FDA say about "research use only" labelling?
Each letter addresses the disclaimer directly and disposes of it in one move. In the TXP letter the agency writes that "[d]espite statements on your product labeling marketing your products 'research use only' ... evidence obtained from your website establishes that your products are intended to be drugs for human use." The NuScience letter uses the same construction against the phrase "for laboratory, research, and analytical use." The reasoning is the intended-use doctrine at section 201(g)(1): labelling does not determine what a product is if the surrounding evidence establishes a different intent. A disclaimer is one piece of evidence and it is outweighed by contrary evidence. This is consistent with the April 2026 letters and should not be read as a change in position.
Why does bacteriostatic water appear in all four letters?
In every one of the four, the reconstitution solvent is itself named among the unapproved drugs - listed as "Bacteriostatic Water 0.9% Benzyl Alcohol" by TXP, "Bacteriostatic water for Peptides (BAC Water)" by NuScience, and "Reconstitution Solution (BAC)" by Peptide Partners. FDA's stated basis is that the solvent was offered alongside and in combination with the peptides. The Royal Peptides and NuScience letters go a step further and cite the seller's own peptide guide and dose calculator, which the NuScience letter characterises as "a resource that provides the means to prepare an injectable drug for human administration."
That is the part with consequences beyond these four firms. It makes the composition of a catalogue - what is sold next to what, and what tooling is published alongside it - independent evidence of intended use, separate from any claim made about a compound.
What kind of product copy did FDA quote?
The quoted passages are not all overt marketing. Several are written in research register - hedged, framed around study findings - and were cited anyway, because they went on to name specific disease states and physiological endpoints in a human context. The distinction the letters draw is not between confident and cautious phrasing. It is between describing what a literature reports and indicating what a product is for.
What this does and does not establish
These are warning letters, not adjudications. Each gives the recipient fifteen business days to respond, and none has been tested in court. They are best read as a current statement of how CDER is assembling intended-use cases against online peptide sellers, and the sample here is four firms, not the market.
Several compounds named across the letters - retatrutide, tirzepatide, semaglutide, PT-141, tesamorelin, SS-31 - are compounds this site publishes literature summaries on. Veridian Research supplies material for in-vitro laboratory research only, not for human or veterinary use. The letters are relevant here as regulatory record, and they document how narrow the line has become between describing a body of research and being read as offering a drug.
Primary sources: the four letters are published in FDA's warning letter database under the MARCS-CMS numbers above.