What the FDA's GLP-1 Warning Letters Say About This Market

We keep a register of FDA warning letters relevant to this market, currently 157 of them. Read by year, it describes a regulator that went from occasional interest to sustained enforcement in about eighteen months: two letters in 2023, ten in 2024, 72 in 2025, and 73 so far in 2026 with the year not finished.

What the letters are about

The distribution is the interesting part. The single commonest category is selling — unlawful sale of unapproved and misbranded drugs to consumers — not manufacturing failure. Add the two misbranding categories and the marketing one, and the overwhelming majority of enforcement in this market is about what sellers said rather than what pharmacies made.

Eight letters concern adulterated drug products. A hundred and fifty concern selling and saying.

That matches what we find reading seller sites all day, and it is worth knowing as a buyer: the failure mode this market is actually being disciplined for is claims, not contamination. Our articles on checking a review score and what a badge tells you cover the consumer end of the same problem.

How many of them are sellers you could buy from

Fifty-four of the 157 letters map to a seller in our register, and 53 seller reviews carry a letter flag. That is roughly one in eleven of the sellers we track — a meaningful minority rather than a fringe.

An error of our own, in the same data

While assembling these figures we found that four of our own seller reviews were stating “4”, “5” and “6 FDA warning letters matched to this operator” — and that none of those four companies had a single letter in the register.

The cause was mundane and the consequence was not. The field holding letters had also been used, historically, to store general FDA-related notes — boilerplate along the lines of “compounded semaglutide is not FDA-approved and has not been evaluated by FDA”, which is true of every compounded product and is not a letter. The page counted the length of that list. Four named businesses were publicly credited with enforcement history they do not have.

It is corrected, an automated check now fails our build if a letter count is ever built from anything other than a letter, and we confirmed the fix did not create the opposite error — those four are now told they have no letter, which is true of them in the register. We are describing it here because an article about other people’s enforcement records that quietly omitted our own mistake would not be worth publishing.

How to read a letter if your seller has one

1. Check the date. A 2023 letter about claims that have since changed is a different thing from one issued last quarter.
2. Read the subject line. “Adulterated drug products” and “false and misleading claims” are not the same order of concern.
3. Check who it was addressed to. Letters go to legal entities, which frequently operate several consumer brands — see who actually runs your brand.
4. Look for what changed afterward. The point of a warning letter is compliance, and the useful question is whether the company complied.
5. Read it yourself. Every letter is published by the FDA, and our warning letters page links each one to its source.