The FDA posted five warning letters to peptide sellers on September 1, 2026. All five were signed on August 24, 2026, all came from the Center for Drug Evaluation and Research (CDER), and all carry the same subject line: Unapproved New Drugs/Misbranded.
Source: FDA Warning Letter Database
The five letters
- Peak Performance Peptides (MARCS-CMS 735127) — FDA letter
- Royal Peptides LLC, Boynton Beach, FL (MARCS-CMS 734884) — FDA letter
- NuScience Peptides LLC, Cornelius, NC (MARCS-CMS 733652) — FDA letter
- Peptide Partners LLC (MARCS-CMS 735063) — FDA letter
- TXP Innovations LLC dba Tex Peptides — see FDA database entry (posted 09/01/2026)
The eight-day gap between signature (08/24) and posting (09/01) is routine — the FDA publishes letters in weekly batches.
What was cited
The Royal Peptides letter cites seven products sold with drug claims after a July 2026 website review: tirzepatide, semaglutide, retatrutide, SS-31 (elamipretide), PT-141, tesamorelin, and bremelanotide-related product, with claims around glucose regulation, insulin sensitivity, weight loss, metabolism, and body composition. The NuScience letter cites nine products including GLP-1/GLP-2/GLP-3 branded research peptides, survodutide, mazdutide, PT-141, tesamorelin, and bacteriostatic water sold alongside peptides.
Retatrutide is an investigational molecule with no marketing approval. The letters treat website claims as establishing intended use as drugs under Section 201(g)(1) of the FD&C Act, making them unapproved new drugs under Sections 301(d) and 505(a) — the "research use only" label did not shield them.
As in prior waves, the letters warn that injectable products are "especially concerning from a public health perspective" because they bypass key bodily defenses, and that failure to correct may result in seizure or injunction without further notice. A written response is typically expected within 15 working days.
What this means for buyers
This is a continuation of the pattern documented in our June 2026 warning-letter analysis: the FDA reviews the totality of website marketing, not the label disclaimer. Before committing to a supplier, search their name in the FDA warning letter database — a history of letters is the strongest negative signal short of an audit.