FDA warns four peptide sellers over semaglutide, tirzepatide and retatrutide sold as research chemicals

The Food and Drug Administration posted four warning letters on September 1, 2026, to companies selling injectable peptides online. All four letters are dated August 24, 2026, and all came from the agency's Center for Drug Evaluation and Research. The companies named are TXP Innovations LLC, which does business as Tex Peptides, Royal Peptides LLC, NuScience Peptides LLC, and Peptide Partners LLC.

The products named in the letters include copies of drugs many readers will recognize. Tex Peptides was cited for selling semaglutide, tirzepatide and retatrutide, along with tesamorelin, bremelanotide and a compound called SS-31. NuScience Peptides was cited for a longer list that added survodutide and mazdutide, two obesity drugs that are still in clinical testing and are not approved anywhere for weight loss.

A research label does not change what the law calls the product

Sellers in this market usually label their vials "for research use only" and state that the contents are not for human consumption. FDA's position in these letters is that the label does not settle the question. What settles it is how the product is presented and what the seller says it does.

The letters quote the sellers' own marketing back at them. NuScience described one product as "a novel investigational peptide being explored for its potential research applications in metabolic disorders," and described survodutide as having "efficacy in promoting weight loss and improving glycemic control." Tex Peptides said its semaglutide product supports "weight loss by reducing appetite," and said tirzepatide offers "a powerful approach to improving blood sugar control and weight management."

Those statements are drug claims, FDA said. That makes the products unapproved new drugs under sections 301(d) and 505(a) of the Federal Food, Drug, and Cosmetic Act. An unapproved new drug is one FDA has never reviewed for safety or effectiveness for the use being advertised, and federal law bars shipping it across state lines. The letters also cite misbranding. In plain terms, misbranding means the labeling does not carry the directions and warnings a person would need in order to use the product safely.

Each company was told to respond in writing to FDA within fifteen business days of receiving the letter, describing what it has corrected and how it will prevent a repeat.

This is the fourth round of peptide letters in nine months

These four letters are not an isolated action. FDA's warning letter database shows a letter to Pinnacle Professional Research, doing business as Pinnacle Peptides, dated December 12, 2025. Five more went out on March 31, 2026, to Lovega LLC doing business as Pink Pony Peptides, Gram Peptides, Prime Sciences, Mile High Compounds LLC and PekCura Labs. Another went to Wholesale Peptide on June 17, 2026.

One filing detail differs. The March letters are listed under the subject heading "Unapproved New Drugs Sold Over the Internet." The four posted this week are listed under "Unapproved New Drugs/Misbranded." FDA did not explain the difference, and it may be an administrative label rather than a change in approach.

A warning letter does not remove the product from sale

A warning letter is the agency's first formal step, not its last. It is not a recall, not a seizure, and not a court order. The company gets its fifteen business days to answer, and FDA can escalate to an injunction or seizure if the response does not satisfy it. In the meantime nothing physically stops the vials from shipping, and readers should expect these products to remain available.

There is also nothing in these four letters about what is actually inside the vials. FDA cited how the products were marketed, not laboratory results on their contents. Purity, dose accuracy, sterility and correct labeling of strength were not the subject of this action. That is a separate question, and these letters do not answer it either way.