What FDA reads on a website before it calls a research product a drug

The 'research use only' label is not what FDA reads. Its 2024 to 2026 warning letters spell out what is: claims, calculators, diluents sold alongside vials, and customer reviews. Here is the rule and the letters in their own words.

By Touchstone PeptidesSeptember 22, 20267 minute read

FDA does not decide whether a product is a drug by reading its label. It reads everything else: the product page, the blog, the calculator, the items sold beside the vial and the reviews. That is the rule in 21 CFR 201.128, and it is why every warning letter to a research-peptide seller from December 2024 to August 2026 sets the "research use only" label aside, in its body or in a footnote.

The rule: intended use is objective intent

21 CFR 201.128 says that the "intended uses" of an article refer to "the objective intent of the persons legally responsible for the labeling of an article," and that this intent "may be shown by such persons' expressions, the design or composition of the article, or by the circumstances surrounding the distribution of the article." It then gives examples:

This objective intent may, for example, be shown by labeling claims, advertising matter, or oral or written statements by such persons or their representatives. Objective intent may be shown, for example, by circumstances in which the article is, with the knowledge of such persons or their representatives, offered or used for a purpose for which it is neither labeled nor advertised.21 CFR 201.128, "Meaning of intended uses"

Three things follow. A disclaimer is one expression among many, and it does not outweigh the rest. "Advertising matter" includes a blog. And "the circumstances surrounding the distribution" means what else is in the cart. The regulation also says that intended use can change downstream: a distributor "who intends an article for different uses than those intended by the person from whom he or she received the article" takes on the labelling duty for the new use. A reseller cannot borrow a manufacturer's research-grade intent and then write consumer copy.

The existing piece on what research use only means describes the line this site draws. The broader legal picture, possession, sale, sport and import, is in are peptides legal in the United States. This one is about how FDA finds the line on someone else's site.

Which statutes the letters cite

Every peptide letter cited below invokes the same four provisions of the Federal Food, Drug, and Cosmetic Act. FDA's Gram Peptides letter of March 31, 2026 states them in order:

Your products are drugs as defined by section 201(g)(1) of the FD&C Act 21, U.S.C. 321(g)(1), because they are intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease and/or intended to affect the structure or function of the body.FDA warning letter to Gram Peptides, March 31, 2026

Your Gram Peptides products are "new drugs" under section 201(p) of the FD&C Act, 21 U.S.C. 321(p), because they are not generally recognized as safe and effective (GRASE) for use under the above-described conditions prescribed, recommended, or suggested in their labeling.FDA warning letter to Gram Peptides, March 31, 2026

The introduction or delivery for introduction into interstate commerce of these unapproved new drug products violates sections 301(d) and 505(a) of the FD&C Act, 21 U.S.C. 331(d) and 355(a).FDA warning letter to Gram Peptides, March 31, 2026

The chain is: intended use makes it a drug under 201(g)(1); no general recognition makes it a new drug under 201(p); no approved application makes shipping it a violation of 505(a) and 301(d). Nothing in that chain concerns what the powder is. It concerns what the seller said about it and what the seller sold next to it. The USApeptide.com letter of February 26, 2025 adds misbranding under 301(a) and the prescription-drug provisions of 503(b), for the same reason.

What counted as evidence, in FDA's words

The letters published as of September 21, 2026 say plainly what the investigators read, and the same kinds of evidence recur.

The disclaimer, set aside. Each letter carries a version of the same sentence, in the body or as a footnote:

Despite statements on your product labeling marketing your products "for research use only" and "not for human or animal consumption," evidence obtained from your website establishes that your products are intended to be drugs for human use.FDA warning letter to Royal Peptides LLC, August 24, 2026

Claims on product pages. The letters quote the seller's own copy back at it. Each of the following was a trial figure or a named condition, printed on a research product's page and cited by FDA as proof of intent:

a semaglutide page that cited a cardiovascular-outcomes trial figure, percentage included (Prime Vitality, Inc. dba Prime Peptides, December 10, 2024)
a product name paired with a named prostate condition (Wholesale Peptide, June 17, 2026)
a PT-141 page naming a sexual-function indication among the conditions it had been trialled for (Royal Peptides LLC, August 24, 2026)

It does not matter that a figure was true of an approved product in a published trial. It matters that it was printed on a research product's page.

A diluent sold alongside the vials. Two of the August 2026 letters cited here and the Gram letter make the same finding about the solvent sold next to peptides.

FDA found that a diluent sold beside the vials was itself a drug, because selling the two together showed they were meant to be combined for human administration (Peak Performance Peptides, August 24, 2026).

The Peptide Partners letter of the same date reaches the identical conclusion about a diluent listed on that site. The solvent is not a drug on its own. It became one because of what it was sold beside.

Guides, calculators and hardware. The Royal Peptides letter names a guide and a calculator, sold alongside a diluent, as evidence of intended human use (August 24, 2026).

The USApeptide.com letter lists a diluent vial and hardware sold on the same site, and explains why FDA regards such products as a particular risk:

Injectable drug products can pose a serious risk of harm to users because they bypass many of the body's natural defenses against toxic ingredients, toxins, or dangerous organisms that can lead to serious and life-threatening conditions such as septicemia or sepsis.FDA warning letter to USApeptide.com, February 26, 2025

Customer reviews. The clearest example is not a peptide letter. FDA's September 8, 2025 letter to PureRawz, a seller of tianeptine products under the same research label, cites a customer review from the site, describing relief from a psychiatric condition, as evidence of intended use.

A review is an "oral or written statement" that the seller chose to publish. The same reasoning applies to any research product.

Is there an FDA "research use only" rule at all?

There is one, and it does not cover peptides. 21 CFR 809.10(c) exempts an in vitro diagnostic product "in the laboratory research phase of development" from certain labelling requirements when it bears the statement "For Research Use Only. Not for use in diagnostic procedures." It applies to diagnostic test components. It has nothing to say about a peptide sold in a vial, and none of the letters cited above accepts the label as a defence.

The phrase on this site describes what the material is supplied for and how the site is written. It is not an exemption, for this site or anyone else.

Why this site is written the way it is

The evidence list above is, read the other way, a list of things not to publish. That is why some pages here answer a different question from the one people typed.

No claim about what a molecule does in a person, anywhere, including the blog. Product pages carry sequence, molecular weight, CAS number, purity, net peptide content and a lot number. That is the whole description.
No calculators, guides, tables of amounts, or preparation steps. Where a search question can only be answered with a use instruction, the page says so and answers the adjacent factual question instead.
Nothing on the site describes any product as something to prepare or use in a person, and the catalog's own limits are stated at what we will not sell.
No reviews of what material did to anybody. A review here is about the shipment and the paperwork.

None of this is a workaround. It is the literal shape of the rule. What this site offers instead is documentation: a second, independent assay on every lot and printed net peptide content.

What to look for on any seller's site

The same evidence doubles as a test of any supplier: a trial figure or named condition on a product page, a diluent or hardware in the catalog, a calculator, or reviews that say what a product did are the sentences FDA quotes back. The full checklist for judging a seller, documents included, is in how to vet a peptide vendor.

Sources

For laboratory research use only. Not a drug, not a supplement, and nothing here is a claim about what any of this material does in a person or an animal.

Two things before you come in.