FDA sends warning letters to five peptide sellers over unapproved drugs
Five peptide vendors received FDA letters citing unapproved and misbranded drugs, but the agency has not said which substances the letters concern.
The FDA has sent warning letters to five companies that sell peptides, citing unapproved new drugs and misbranding, according to the agency's warning letter database [1]. All five letters carry an issue date of Aug. 24, 2026, and were posted for public view on Sept. 1, 2026 [1].
The companies are Royal Peptides LLC, NuScience Peptides LLC, Peak Performance Peptides, Peptide Partners LLC, and TXP Innovations LLC, which does business as Tex Peptides [1]. Each letter came from the FDA's Center for Drug Evaluation and Research, and each is listed under the subject "Unapproved New Drugs/Misbranded" [1]. The listing does not name the specific peptides involved, and the excerpt column for each entry is blank [1].
Which substances the letters concern has not been disclosed. FDA has said generally that it warned companies that illegally sold unapproved drugs containing semaglutide, tirzepatide, retatrutide, survodutide or mazdutide labeled "for research purposes" or "not for human consumption" [2]. Those products were sold directly to consumers for human use with dosing instructions, and the agency urges consumers not to buy them, describing them as of unknown quality and potentially harmful [2].
Two of those ingredients, retatrutide and cagrilintide, cannot be used in compounding under federal law, are not components of any FDA-approved drug, and have not been found safe and effective for any condition [2]. FDA says it has warned telehealth companies for marketing unapproved drugs such as retatrutide, ingredient distributors for selling retatrutide and other GLP-1 drugs to compounders, and outsourcing facilities for repackaging retatrutide [2].
FDA also publishes counts of reported problems. As of May 31, 2026, the agency had received 990 reports of adverse events associated with compounded semaglutide and more than 730 associated with compounded tirzepatide [2]. FDA says it is not always possible to determine whether an adverse event resulted from the drug or whether other factors contributed, and that reporting is likely incomplete because state-licensed pharmacies that are not outsourcing facilities are not required to submit adverse events to the agency [2]. Many reported events for compounded products appear consistent with those for FDA-approved versions [2].
Separately, FDA says it received multiple reports of adverse events, some requiring hospitalization, that may be related to dosing errors with compounded injectable semaglutide, including patients measuring incorrect doses and health care professionals miscalculating doses [2].
Why it matters for patients
Products sold for research use are not FDA approved, which means the agency does not review them for safety, effectiveness or quality before they are marketed [2]. FDA's stated position is that compounded drugs should be used only in patients whose medical needs cannot be met by an FDA-approved drug, that patients should get a prescription from a doctor and fill it at a state-licensed pharmacy, and that questions about a medicine should go to the prescriber or the pharmacy that made it [2].
FDA lists red flags for consumers, including a seller that does not require screening and a prescription from a licensed doctor, labels with spelling errors or incorrect pharmacy addresses, prices that seem too good to be true, and medicine that arrives in damaged packaging or without instructions for use [2]. The agency also says injectable GLP-1 drugs that arrive warm or with inadequate ice packs should not be used [2], and that multi-dose vials should be discarded 28 days after first use even if medication remains [2].
What happens next
The warning letter table shows no response letter or closeout letter for any of the five companies as of the posting date [1]. FDA notes that matters described in a warning letter may be subject to later interaction between the agency and the recipient that could change the regulatory status of the issues discussed [1]. Whether any of the five companies has responded, and whether FDA plans further action, has not been reported.
Sources
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