JAMA Medical News Details Black Market for Unapproved Retatrutide and Zenagamtide

A Medical News feature published October 9, 2026 in JAMA examined the online black market for retatrutide and zenagamtide, two injectable weight-loss peptides that are not approved for any use by the FDA, the European Medicines Agency, Australia's Therapeutic Goods Administration or any other regulator. Both remain in active clinical development: retatrutide, an Eli Lilly triple agonist of the GIP, GLP-1 and glucagon receptors, and zenagamtide, Novo Nordisk's GLP-1 and amylin receptor co-agonist previously known by the code name amycretin.

The article, written by JAMA senior staff writer Rita Rubin, said demand has been driven in part by the roughly 40% of US adults who have obesity and by insurers that often do not cover approved GLP-1 therapies. It cited a June investigation by the advocacy group Public Citizen that found hundreds of TikTok and Instagram posts, including from influencers with large followings, promoting retatrutide as superior to approved drugs and linking to sellers, with some posts including dosing and injection instructions. Some sellers label their products "for research purposes only" while still providing dosing instructions, a practice University of Colorado pharmaceutical outcomes researcher Michael DiStefano, quoted in the article, called "just some sort of legal cover." Peter Pitts, a former FDA associate commissioner, was quoted calling the trade "digital-age bootlegging."

The JAMA article reported specific findings about what buyers are actually receiving. Citing Australian reporting, it said the Therapeutic Goods Administration tested a product sold as retatrutide after a patient suffered a potentially fatal ruptured esophagus, and found the product contained a high dose of semaglutide and no retatrutide at all. It said Victoria's health department issued a June alert linking six cases of liver toxicity to products labeled retatrutide or sold under nicknames such as "reta," "R-10" and "R-20." Separately, it said University of Queensland researchers who tested three products labeled as containing 10 mg of retatrutide found actual retatrutide in all three, but at levels that diverged sharply from the label, ranging from roughly half the stated dose to roughly double it; the researchers found trace lead, copper and zinc below levels considered harmful but did not test the products for sterility or bacterial endotoxins.

A separate case report published October 7, 2026 in BMJ Case Reports, unrelated to the JAMA feature, documents a similar pattern. Physicians at Zurich's UniversitätsSpital described a woman in her mid-20s admitted with five days of persistent nausea, vomiting and diarrhea after a self-described "life coach" with no medical qualification administered four weekly, dose-escalated subcutaneous injections of an unverified product reported to contain retatrutide as part of a wellness program. The authors, who scored the case a 7 on the Naranjo adverse-drug-reaction scale indicating probable causality, wrote that the patient "did not consider the injections to be medication" and had not disclosed them until a second, non-judgmental history-taking two days into her admission. Her symptoms resolved within a week. The authors said the product's identity, purity and actual dose were never independently verified, and urged clinicians to explicitly ask patients about peptides, research chemicals and substances recommended by non-medical wellness providers.

On enforcement, the JAMA article said the FDA has issued 21 warning letters tied to retatrutide sales since December 2024, but as of late September had not posted any warning letters specific to zenagamtide sellers. It said a warning letter sent to one seller, Tex Peptides, on August 24, 2026 had not stopped the company from prominently featuring retatrutide on its site five weeks later. Yale family medicine physician and health services researcher Reshma Ramachandran was quoted describing the FDA's enforcement capacity as "pretty limited." The article said Eli Lilly filed six new lawsuits in August 2026 against sellers of retatrutide-labeled products, with a company spokesperson quoted saying, "What is being sold on the black market is not medicine, it is entirely unverified, unapproved, and not worth the risk." It said Novo Nordisk has filed more than 130 lawsuits against compounding pharmacies, telehealth platforms and other sellers of unapproved semaglutide-related products, resulting in 90 court judgments, and that Mississippi's boards of medical licensure, nursing and pharmacy issued a joint statement in August 2026 saying that a medical professional's involvement in recommending, supplying, prescribing or administering the substances constitutes the unlawful practice of medicine.

The JAMA feature also referenced a JAMA research letter published August 4, 2026 (doi:10.1001/jama.2026.9131), in which Yale researchers including Ramachandran used a simulated patient profile to request GLP-1 prescriptions from 49 telehealth platforms; 45 issued a prescription and 34 mailed medication directly to the simulated patient, with a small number of sites offering retatrutide-labeled products. That study did not independently test what was actually shipped.

The article closed with caution from obesity medicine researchers at Boston University's Chobanian & Avedisian School of Medicine. Ivania Rizo was quoted saying she would "encourage patients to be honest with their health care team about anything they are taking," and that improving the affordability of, and access to, approved treatments "is essential if we want patients to avoid potentially risky alternatives." Retatrutide and zenagamtide remain unapproved investigational compounds; this report describes regulatory and product-safety findings as reported by JAMA and BMJ Case Reports and is not guidance on dosing, sourcing or use of either substance.