The FDA's steady run of warning letters to online peptide sellers continued this quarter, with three more companies cited on August 24, 2026, for marketing unapproved drug products under the guise of "research use only" peptides.
Who Was Cited
The three companies named are Peptide Partners LLC, based in Sarasota, Florida; Peak Performance Peptides; and NuScience Peptides LLC, based in Cornelius, North Carolina. All three received individual warning letters from the FDA on the same date, each detailing similar patterns of alleged violations found on the companies' websites.
What They Were Selling
Across the three letters, the FDA identified a broad and overlapping product list, including research-labeled versions of semaglutide, tirzepatide, and retatrutide (marketed under names like "GLP-1 S," "GLP-2 T," and "GLP-3 Reta" or "GLP-3R"), along with survodutide, mazdutide, elamipretide (SS-31), tesamorelin, bremelanotide (PT-141), and bacteriostatic water used for reconstitution. Several listings paired peptides together, such as a tesamorelin-ipamorelin blend.
The FDA's objection was not simply that these products existed, but how they were marketed. Despite disclaimers stating the products were "not intended for human or veterinary use," the agency pointed to specific website language making therapeutic claims: descriptions of effects on "appetite suppression, energy expenditure, and fat distribution," "insulin secretion, satiety pathways, and body weight management," reductions in "oxidative stress" and improvements in "mitochondrial function," and effects on "sexual arousal and neuroendocrine regulation." The FDA considers claims like these enough to establish a product as an unapproved new drug, regardless of any research-use disclaimer attached to it.
The Legal Basis
Each letter cites violations of the Federal Food, Drug, and Cosmetic Act, specifically the introduction of unapproved new drugs into interstate commerce under section 505(a) and misbranding under related provisions. None of the cited products carry FDA approval for the conditions described on the sellers' sites. As in prior rounds of similar letters, the FDA emphasized that injectable products carry a distinct risk because they bypass the body's normal defenses against contamination and impurities, a risk that exists independent of whatever the injected substance is claimed to do.
Not the First, and Likely Not the Last
This is at least the second distinct round of peptide-seller warning letters in 2026, following an earlier batch covered previously on this site that targeted four other companies over weight-loss peptide knockoffs. The recurrence underscores a pattern: enforcement is picking off individual sellers as they're identified, rather than resolving the underlying gray market for research-labeled peptides in one action.
What Happens Next
Companies that receive an FDA warning letter typically have 15 business days to respond with a plan to correct the violations. A warning letter is not a recall, a criminal charge, or a court order; it is a formal notice that precedes potential further action, including seizure, injunction, or referral for prosecution, if the company does not come into compliance.
The Bottom Line
None of the products named in these letters are approved substitutes for the FDA-approved drugs whose active ingredients they claim to replicate. A product labeled semaglutide or tirzepatide sold outside the pharmacy supply chain has not been verified for identity, purity, or dose accuracy by any regulator. Anyone considering a peptide therapy, approved or otherwise, should talk to a licensed physician about legitimate treatment options rather than relying on a research-chemical listing's own description of what a compound does.