FDA to Five Online Peptide Sellers: A 'Research Use Only' Label Does Not Decide What You Are Selling
Published: September 30, 2026 · 3 min read · By Grey Peptides News Desk · ✓ Sourced
On August 24, 2026, FDA's drug center sent warning letters to five online peptide sellers, in North Carolina, Florida, Texas and Arizona, and posted them on September 1. Each says the products it names are unapproved new drugs, and each rejects the same defence: labels saying 'research use only' or 'not for human consumption' did not outweigh what the sellers' own websites showed. We missed them when they were posted; this is the catch-up.
What the letters say
The letters follow FDA reviews of the sellers' websites; four of them date the review to July 2026. Across the letters, the products named include semaglutide, tirzepatide and retatrutide, often under the grey-market nicknames our guide to GLP-3 names decodes ("GLP-1 Sema", "GLP-2 Tirz", "GLP-3 RT"), along with survodutide, mazdutide, SS-31 (elamipretide), PT-141 (bremelanotide), tesamorelin and a tesamorelin-ipamorelin blend. FDA says each is a new drug with no approved application, so selling it across state lines violates sections 301(d) and 505(a) of the Food, Drug, and Cosmetic Act. Every letter adds that injectable products bypass some of the body's defences against toxins and microorganisms.
Why the label did not help
Whether something is a drug turns on its intended use, and FDA reads that from the whole website, not the disclaimer. The letters quote product pages describing weight loss, glycaemic control, sexual function and fat reduction; in one case the evidence was a linked PubChem page describing semaglutide's cardiovascular benefit and weight loss. Selling bacteriostatic water beside the peptides counted as well. In at least three letters the water is itself listed as an unapproved drug, because it was sold to reconstitute products meant for injection. Two letters go further: the sellers offered a peptide calculator, in one case with a peptide guide, which FDA describes as the means to prepare an injectable drug for human administration.
What the letters do not cover
None of the five mentions BPC-157 or TB-500, the peptides at the centre of the compounding debate that FDA's advisory committee took up in July; their status is unchanged, and our regulatory tracker carries it. A warning letter is FDA's position, not a court finding. The letters ask for a response within 15 business days, and FDA says unaddressed violations can lead to seizure or injunction without further notice. The letters also say nothing about the contents of any vial. Our guide to checking a certificate of analysis covers what testing can and cannot tell a buyer.
Related on Grey Peptides
Which molecule each nickname in the letters stands for. Regulatory tracker
Each tracked peptide's FDA, compounding and WADA status, dated at source. Verify a certificate of analysis
What a COA can prove about a vial, and what it cannot.
Five letters dated August 24, 2026 and posted on fda.gov September 1, 2026, each read in full September 30, 2026. The link goes to the first; the other four are on FDA's warning-letter index.