What FDA cited in the August 2026 peptide warning letters
On 1 September 2026 FDA posted four warning letters to its public database, all issued on 24 August 2026, to companies selling peptides online. The recipients were TXP Innovations LLC dba Tex Peptides (ref. 735067), Royal Peptides LLC (734884), NuScience Peptides LLC (733652) and Peak Performance Peptides (735127). The letters share a structure, and the point they turn on is worth stating precisely: in every one, FDA built its case out of the company's own website copy rather than its product labeling, and held that a research-use-only disclaimer did not change the conclusion.
What did FDA allege?
The allegation common to the letters is the introduction of unapproved new drugs into interstate commerce, under sections 301(d) and 505(a) of the FD&C Act, 21 U.S.C. 331(d) and 355(a).
The reasoning runs through the statutory definition of a drug. Section 201(g)(1), 21 U.S.C. 321(g)(1), reaches articles "intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease, and/or intended to affect the structure or any function of the body." FDA read the sellers' product pages as establishing that intent. Once the articles are drugs, they are "new drugs" under section 201(p), 21 U.S.C. 321(p), because, in the agency's words, they are "not generally recognized as safe and effective (GRASE) for use under the conditions prescribed, recommended, or suggested in their labeling" — and a new drug may not be introduced into interstate commerce without an approved application.
FDA's index classifies all four under "Unapproved New Drugs/Misbranded," but the Peak Performance letter carries no separate misbranding allegation. The index heading is not a reliable description of the counts in any individual letter.
What did FDA say about the disclaimers?
Each letter disposes of the research-use-only framing in a footnote, in materially identical terms. The NuScience letter states: "Despite statements on your product labeling marketing your products 'for laboratory, research, and analytical use' and 'not intended for human or veterinary use,' evidence obtained from your website establishes that your products are intended to be drugs for human use." The Tex Peptides, Royal Peptides and Peak Performance letters carry the same construction against their own respective disclaimer wording.
The structure of that sentence is the substance of it. FDA is not disputing that the disclaimer was present. It is holding that intended use is determined by the whole evidentiary record, and that copy elsewhere on the site outweighs a statement on the label.
What was treated as evidence of intent?
Two categories. The first is product-page text describing what the compounds do in the body — the second prong of the 201(g)(1) definition, effect on structure or function.
The second is more procedural, and the less discussed. In the Royal Peptides letter, FDA noted that the company marketed bacteriostatic water alongside a "peptide guide" and "peptide calculator," calling them "resources that collectively provide the means to prepare an injectable drug for human administration." The NuScience letter makes the same point about a calculator offered with reconstitution solvent. The agency treated the surrounding apparatus of a storefront as probative of intended use, independent of the descriptive copy.
What these letters do not establish
They are not adjudications. A warning letter states the agency's position and opens a response window — fifteen business days, per the Royal Peptides letter — and no court has ruled on any of the four.
They also make no analytical allegation. Nothing in the letters read for this piece asserts contamination, subpotency, misidentification or a manufacturing failure; the theory is intended use as evidenced by marketing, not product quality. Commentary treating this round as a purity or testing action is not supported by the documents. FDA does not appear to have issued a press announcement alongside the postings, as it did for earlier telehealth rounds.
Veridian Research supplies material for in-vitro laboratory research only.
Sources
FDA warning letters, all 24 August 2026, posted 1 September 2026: Tex Peptides (735067), Royal Peptides (734884), NuScience Peptides (733652), Peak Performance Peptides (735127).