Unapproved Retatrutide Use Challenges Clinicians

Retatrutide, an investigational triple hormone receptor agonist that shows promise for weight loss in ongoing phase-3 clinical trials, is being sold openly across the internet and prescribed by licensed physicians online and in diverse clinical settings across the US, investigations have found.

The phenomenon of such easy access to a drug that’s not approved anywhere for any indication is arguably without precedent.

Patients are discovering the drug — a GLP-1, glucose-dependent insulinotropic polypeptide (GIP), and glucagon agonist — through social media, purchasing it from vendors online, and arriving at clinic appointments either asking about it or disclosing they are already using it. News reports state that everyone from “shadowy online vendors” to physicians and nurses is illegally promoting the drug before it receives the FDA approval.


“I’ve never seen this, not ever,” Anne Peters, MD, a professor of clinical medicine and a clinical scholar at the Keck School of Medicine, University of Southern California, Los Angeles, told Medscape Medical News. “I’ve seen this happen with supplements, but not a drug that’s under study to be FDA-approved.”

Although the retatrutide phase 3 trials to date have been promising, many drugs have failed to advance from that stage because of unexpected adverse outcomes that only emerge at scale, said Courtney Younglove, MD, founder and medical director of Heartland Weight Loss in Overland Park, Kansas.



“What’s happening now is a huge, unregulated human experiment,” she told Medscape Medical News. “Yes, we know retatrutide works to cause weight loss, but the more important data — who are the best candidates, what dose(s) do we use, how to titrate them, what adverse effects to watch for — we don’t know.”


Given the magnitude of weight loss seen in retatrutide clinical trials, its unsupervised use concerns Rachel Pessah-Pollack, MD, a clinical professor of medicine at NYU Langone Health, New York City. “Retatrutide needs to be tailored to the patient who would benefit from it. If the treatment is given to patients who do not require this degree of weight loss, there can be significant loss of lean muscle, gallstones — especially with rapid weight loss — and nutritional deficiencies,” she said.

A recent study of self-reported side effects among Reddit users taking retatrutide found that among 13,589 individuals, 7823 (57.6%) had at least one side effect. In the phase 3 trial, side effects were mostly gastrointestinal (GI) issues but that was not the case with Reddit users. They most often described appetite increase, fatigue, increased energy, nausea, food craving, insomnia, and elevated heart rate.

Peters said she wonders if the Reddit users are even getting real retatrutide, given the mismatch in side effects. People she knows who say they are using it also aren’t experiencing GI side effects, nor are they losing much weight, she said.


“Compounded retatrutide often comes in a powder that users reconstitute. For all I know, they might be taking baby powder,” Peters said.

What Investigations Show

Recent investigations by CBS News, the New York Times, and Public Citizen have revealed just how easy it is to get the drug and the danger that comes with taking an unapproved medication.

CBS News reported that more than 120 websites are selling or promoting retatrutide and that at least 50 clinics staffed by licensed physicians and nurse practitioners are openly advertising the drug. The investigation found that retatrutide exposures documented by poison centers rose to an average of 95 cases per month in the first 4 months of 2026, a 265% increase from the last 4 months of 2025.

After being contacted by CBS News, at least 21 clinics removed retatrutide from their websites or altered their language, according to investigators. Others defended the practice, saying they were confident enough in clinical trial data that they didn’t need to wait for the FDA approval.


The investigation also found that retatrutide is being sold at varying prices through medical spas, telehealth clinics, and compounding pharmacies, a number of which are named; several clinics continued advertising the drug after being contacted by reporters; and some compounding pharmacies continued operations despite state enforcement actions.

The CBS report prompted the Alliance for Pharmacy Compounding to issue a notice on the organization’s website, noted Scott Brunner, the organization’s CEO. It states that retatrutide is an experimental drug that “compounding pharmacies have zero legal grounds to compound. The [CBS investigation] is worth reading carefully because it calls out licensed compounding pharmacies alongside research-grade peptide mills, unlicensed online vendors, and med spas — and in some of those cases, the inclusion is warranted.”

Because retatrutide has not yet been approved by the FDA, “it is illegal for use in compounding,” Brunner told Medscape Medical News. “Retatrutide products currently available appear to be made with a research-grade [active pharmaceutical ingredient] — also illegal for use in human drugs. While there may be rare exceptions in which a pharmacy is preparing these drugs with research-grade product, the retatrutide being sold at present is generally coming from non-pharmacy entities and are being dispensed by med spas and the like.”

The New York Times documented how customers are obtaining retatrutide through multiple channels. People can purchase the drug from WhatsApp, Telegram, Discord, and Reddit groups, which are often run by middlemen who’ve bought it in bulk, usually from China, and repackaged the product or filled empty injection pens and added their own branding. Others purchase from online storefronts listing the drug as “for research purposes only.”


The investigation also discovered a black market operating through decentralized supply networks; customers using third-party testing labs (some of questionable quality) to verify purity; and wide variation in the contents and purity of what consumers receive, with some vials potentially containing a different weight-loss drug altogether.

Public Citizen found that the FDA issued warning letters to 14 retatrutide vendors since December 2024, but 11 of them continued advertising the drug or related peptides as of May 2026 and eight are still actively selling retatrutide. Enforcement has stalled at the warning letter stage with minimal follow-up. The investigation determined that the FDA lacks the resources to pursue seizures and injunctions without Department of Justice coordination; state-level enforcement varies widely and is inconsistently applied; and social media influencers are serving as unregulated sales channels for the drug.

A spokesperson for Eli Lilly, which developed the drug, emphasized that it should not be sold or used yet. “Retatrutide has not been approved anywhere in the world, and it is legally available only to participants in Lilly’s clinical trials,” he told Medscape Medical News.


“Anyone purporting to sell retatrutide to consumers is breaking the law,” he said. “We have referred dozens of black-market retatrutide sellers to regulators and law enforcement and call on them to take decisive action to fight this urgent threat to public health. Social media is driving the sale of black market retatrutide. We have reported thousands of illicit retatrutide posts and ads, but platforms are often slow to act and by that point the damage is already done. Social media platforms need to shut this down immediately.”

In a warning on its website, the company states: “Anything sold to consumers outside of [clinical trials] is illegal, with no way to verify its safety, purity, or dosing. Taking unregulated substances poses serious health risks, and Lilly continues to work with law enforcement and regulatory authorities to combat black market drugs.”

And yet, there seems to be no end in sight to the retatrutide tidal wave.
What Clinicians Are Doing

For weight-management specialists grappling with the problem, a key challenge is managing patients who have already obtained retatrutide or what they think is retatrutide on the black market.


“My issue is safety,” said Peters. “I can’t assess risk if I don’t know the exact composition of a product.”

When patients disclose that they are using retatrutide, Peters requests documentation of the source. “Patients mostly say it’s from China. But I don’t have a printout in Chinese that says what this is or what the ingredients are, and so I don’t have any way to validate what they are and where they came from. Some patients have even told me that they’re getting the drug from the best place in China. But how do we even rank these places?”

Peters’ approach is to counsel patients on the unknowns and recommend they wait for the FDA approval. She closely follows those who continue taking the drug to make sure that their liver function is normal, their kidney function isn’t altered, and their complete blood count is okay. She also reminds patients that treatment with GLP-1-based therapies is meant to be ongoing and that if they stop, they can get metabolically worse as they regain the weight.


Pessah-Pollack said that while the data for retatrutide are “exciting and promising,” she won’t prescribe it until it gains the FDA approval to ensure it is used safely. Nevertheless, she has had patients who are buying retatrutide from a compounded pharmacy. For those patients, her first step is to review the risks in detail and offer to switch them to an FDA-approved GLP-1 or GLP-1/GIP drug.

“In situations where they insist on continuing their [retatrutide] treatment, they are receiving the medication through another prescribing clinician,” she said. “I encourage them to determine their dosing and review the importance of dietary modifications on weight-loss medications, counsel regarding GI side effects, and encourage resistance exercises. I review the risks of too much weight loss and offer to monitor them alongside their treating clinician.”

Younglove noted that patients often feel dismissed by traditional healthcare providers and turn to alternative markets when they perceive that approved options are inadequate or inaccessible.

“Clinicians should invest time in genuine conversations with patients about why they have sought out an unapproved drug and what gaps exist in available treatment options,” she said. “Understanding this context allows clinicians to engage patients with empathy rather than judgment. The patient is not reckless; they are responding to persuasive marketing in an environment where the FDA’s enforcement is visibly absent.”

Younglove has never had a patient admit to taking retatrutide. “I’ve had several ask me what I thought about it and if I would consider prescribing it, and it’s opened the door to a good conversation,” she said. “I would not refer that patient to anyone, as it would, in my mind at least, feel like condoning experimental treatments. Anyone prescribing retatrutide in my community is essentially working in fringe, nonevidence-based medicine, which doesn’t align with my values.”


Peters and Younglove reported having no competing interests. Pessah-Pollack declared having served on advisory boards for Boehringer Ingelheim and Eli Lilly.

https://www.medscape.com/viewarticle/unapproved-retatrutide-use-challenges-clinicians-2026a1000lqj