Health officials are warning people about unapproved weight loss injections after reports of a man’s death following use of a version of the medication that has not been cleared for public use.
Prescription weight loss treatments such as Wegovy and other GLP-1 medicines have surged in popularity, with more people turning to medical options to help manage obesity and weight-related conditions.
But alongside the rise in legitimate treatments, concerns have also grown around black-market products and substances being sold before they have been approved by regulators. Health agencies in the UK have repeatedly warned that fake or unlicensed weight loss injections can contain the wrong ingredient, the wrong dose, or harmful contaminants.
One such drug is retatrutide, a medication made by Eli Lilly that is still being studied in clinical trials and is not licensed for general use. Lilly says the drug remains investigational and should only be used by participants in its own clinical studies. In 2025 and 2026, the company announced several positive Phase 3 trial readouts, but that does not mean the drug is approved for sale or prescribing to the public.
“Retatrutide is an investigational molecule available only to participants in Lilly’s clinical trials, where its safety and efficacy are still being evaluated. It has not been approved by any regulatory agency, and no one should take anything claiming to be retatrutide outside of a Lilly-sponsored clinical trial.
“Illicit retatrutide products may contain unknown ingredients, harmful contaminants and impurities.”
The Daily Mail reported that a man in his 30s in the UK died after taking an unapproved version of the drug.
According to the report, he experienced complications after using it, while the Medicines and Healthcare products Regulatory Agency (MHRA) has logged suspected side effects linked to retatrutide. The MHRA has also warned about the risks of illegal supply chains and, in October 2025, said officers had seized more than 2,000 unlicensed retatrutide and tirzepatide pens in a major raid on an illicit manufacturing facility.
However, those reports do not prove that retatrutide directly caused either the side effects or the man’s death. They record symptoms and incidents reported while patients were taking the drug.
Experts say one of the biggest dangers is that people buying injections online or through informal channels may not be getting retatrutide at all.
Naveed Sattar, professor of cardiometabolic medicine at the University of Glasgow, warned about the dangers of products being sold as retatrutide outside official channels.
“No one in the UK should be on a drug that is not licensed or has not been approved by MHRA.
“People need to be very wary of something that’s been sold to them called retatrutide because it is likely not retatrutide.
“They could be injecting into their body any substance that could potentially cause them harm.
“I would urge people not to buy things that are not licensed and not from proper manufacturers. Otherwise, you could be putting yourself into harm’s way.”
Officials have also warned that social media sellers and fake pharmacy websites continue to target people seeking rapid weight loss, often using misleading claims and pressure tactics. UK regulators have said prescription-only weight-loss medicines should only be obtained through a qualified healthcare professional and a legitimate prescription.
Eli Lilly also reiterated that the drug is still experimental and should not be taken outside its official studies.
“Retatrutide is an investigational, once-weekly, triple hormone receptor agonist, which activates the body’s receptors for glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1), and glucagon.
“It is an investigational molecule that is legally available only to participants in Lilly’s clinical trials. It has not been reviewed or approved by any regulatory agency in the world.
“No one should consider taking anything claiming to be retatrutide outside of a Lilly-sponsored clinical trial. The company continues to warn the public about the potential dangers of fake medicines.”