On September 1, 2026, the U.S. Food and Drug Administration published five warning letters issued August 24 to businesses selling research peptides online. The recipients were Peak Performance Peptides, Royal Peptides LLC, NuScience Peptides LLC, Peptide Partners LLC, and TXP Innovations LLC, doing business as Tex Peptides.
The letters are important, but not because they prove that every listed vial was chemically impure. They do not. FDA’s stated concerns focused on how the products were presented and sold: the claims made on product pages, the uses those claims implied, and, in several cases, the sale of bacteriostatic water alongside products the agency said were intended for injection.
What FDA said
FDA said it reviewed the companies’ websites in July 2026. Across the five letters, the agency identified products including semaglutide, tirzepatide, retatrutide, SS-31 or elamipretide, tesamorelin, PT-141 or bremelanotide, and other compounds.
The recurring issue was not simply that these names appeared in a catalog. FDA quoted product-page language describing effects on weight, glucose regulation, appetite, metabolism, sexual function, tissue repair, neuroprotection, cancer, and other health-related outcomes. The agency said those claims provided evidence that the products were intended to diagnose, cure, mitigate, treat, or prevent disease, or to affect the structure or function of the body.
Under the Federal Food, Drug, and Cosmetic Act, intended use is central to whether an article is regulated as a drug. FDA alleged that the cited products were unapproved new drugs because no approved applications were in effect for the products as marketed.
Why “research use only” was not enough
The letters illustrate a point that is easy to miss: a disclaimer is only one part of the evidence.
A site can display “research use only” while other parts of the same page describe human outcomes, therapeutic effects, or body-function changes. FDA’s letters show that the agency examined the overall presentation rather than treating the disclaimer as a shield.
Several letters also cited the sale of bacteriostatic water next to the peptide products. FDA argued that selling those items together helped demonstrate an intended combined use for injection. Regulators looked beyond an isolated sentence and considered the surrounding commercial context.
This does not mean that every scientific discussion creates the same legal risk. It does mean that copying clinical language onto a sales page, especially when it is framed as a benefit or expected outcome, can communicate an intended use that conflicts with a research-only label.
What the warning letters do not establish
- They are not laboratory reports.The letters do not present independent purity, identity, sterility, endotoxin, or content results for the cited products.
- They are not product approvals or recall notices.They describe violations FDA says it identified and direct each recipient to respond with corrective actions.
- They may not be the final regulatory event.FDA cautions that later interaction with a recipient may change the status of issues described in a warning letter.
COA quality and regulatory status are different questions
A COA asks: What did a laboratory test in the submitted sample, by what method, and what result did it report?
Regulatory review asks different questions: How is the product represented? What use does the seller communicate? Is there an approved application for the product as marketed? Does the surrounding sales context point toward human or veterinary use?
A detailed, verifiable COA may strengthen confidence in a specific analytical result. It does not answer those regulatory questions. Conversely, a warning letter about marketing does not automatically tell us the purity or content of a particular vial.
What readers should check now
- 01Exact claims
Does the page describe disease treatment, weight change, appetite, sexual function, recovery, or another human outcome?
- 02Product context
Are administration supplies or reconstitution products sold in a way that suggests a particular use?
- 03Approval language
Does the site distinguish an investigational compound from an FDA-approved drug and approved indication?
- 04Document scope
Does the COA report identity, measured content, a lot number, sterility, endotoxin, and contaminants—or only purity?
- 05Current status
Does FDA’s database show a response or close-out letter after the original warning?
The Compound IQ takeaway
The newest FDA letters are not evidence that COAs no longer matter. They are evidence that COAs answer only part of the question.
“99% pure,” “third-party tested,” and “research use only” can all appear on the same website. None of those phrases, standing alone, establishes a complete quality profile, regulatory compliance, or suitability for use.
The right approach is to separate the claims, inspect the documents, identify the missing evidence, and check the current regulatory record. Evidence before the headline.
Compound IQ has no affiliate or commercial relationship with the five companies named in this article. This article analyzes public FDA records and does not provide medical or legal advice, assess any product for human use, or independently test any product.