Unapproved retatrutide: what users report and what FDA says
An analysis of 7 823 forum users found fatigue, more appetite and a racing heart; the authors call it exploratory and FDA warns about quality.
A study in the journal JAMA Network Open, published online on Oct. 14, 2026, examines what effects social media users say they felt with retatrutide, an investigational drug that no health authority has approved and that is sold online without medical supervision. The team, from the University of Pennsylvania, collected public Reddit posts and ran them through a language model that sorted out who said they used the product and logged the symptoms they described. The authors themselves call the results hypothesis-generating: they do not measure how often anything happens or whether the drug causes it.
The FDA, the U.S. drug regulator, maintains, on a page current as of Oct. 1, 2026, that retatrutide cannot be prepared by compounding pharmacies: the compound is not part of any approved drug and nobody has shown it to be safe or effective for any condition. It says it sent warning letters to telemedicine firms, distributors and sellers of products labeled "for research" or "not for human consumption". It asks consumers not to buy them, because their quality is unknown and they could be harmful.
What the study measures
The design is cross-sectional: a program read the texts, nobody reviewed the cases medically and there was no clinical trial. The corpus totals 148 640 posts and comments, written by 38 936 users in 27 communities; messages about ongoing use run from March 2023 to the end of 2025. After filtering, the final analysis came to 7 823 users.
| Reported effect | Users |
|---|---|
| Greater appetite | 17.1% |
| Fatigue | 15.2% |
| More energy | 12.4% |
| Nausea | 11.6% |
| Insomnia | 6.1% |
| Faster pulse | 4.8% |
| Fast heartbeat | 3.8% |
These are self-reports from forums, without clinical confirmation. The authors made no statistical comparisons with semaglutide or tirzepatide, and acknowledge they could not verify the identity, purity or dose of what each person used, or what other drugs they took. The manual check covered just 100 messages. One author reports having received support from Novo Nordisk and Currax Pharmaceuticals unrelated to this work.
The FDA adds that, as of May 31, 2026, it had received 990 adverse-event reports tied to compounded semaglutide and more than 730 tied to compounded tirzepatide, and estimates that underreporting is likely. About the unauthorized versions, the agency says they do not go through its review of safety, effectiveness and quality before being marketed.
The FDA's warning applies to the general population of the United States and refers to these unapproved products; the study provides no safety data by group, such as pregnancy or prior conditions. It was not checked whether Mexico's Cofepris has issued an alert on retatrutide, and there is as yet no second peer-reviewed study confirming the profile of effects.
