Doctor warns ‘King Kong’ weight-loss drug retatrutide comes with ‘life-threatening’ risk
Medics have issued an urgent warning around an experimental weight loss medication which is currently undergoing clinical trials.
GLP-1 medications have seen an explosion in popularity for weight loss, and now a new 'triple agonist' drug is in development.
This will impact on not just one, but three hormones in the body with the aim of being more effective in supporting weight loss, and preventing loss of muscle mass.
The drug is called retatrutide and is not yet available publicly, and Eli Lilly has said that the experimental medication is only available as part of an official clinical trial.
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However, a doctor in Australia has issued a warning after several people became ill after taking a medication which was labelled as retatrutide, the Sydney Morning Herald reported.
Dr Caroline McElnay is the Chief Health Officer in Victoria, Australia, and warned about products labelled as retatrutide being purchased on the internet.
Dr McElnay said that they had received notification of six cases of patients developing acute liver toxicity after injecting medications labelled as retatrutide since January 2026.
A health alert has also been issued over the medication.
“These products have been purchased online, through friends and through social media accounts,” it said.
“These toxic effects are possibly associated with a contaminant in the products labelled as ‘Retatrutide’ and all such products are at risk.
“Unapproved peptide products, particularly those that are injected, carry significant safety risks, including contamination, infection or local tissue damage.”
The Therapeutic Goods Administration, which is a regulatory body for drugs in Australia, has also issued a warning about retatrutide.
Professor Michael Kidd, Australia's Chief Medical Officer, said: “Some of these products have not undergone sufficient human clinical trials and may cause significant harm.
“Australians should not use these products and should seek advice from their trusted healthcare professional.”
Retatrutide is not currently licensed as a drug as it is still undergoing clinical trials, meaning that it is only available as part of a trial.
However, the explosion of popularity in weight loss drugs has led to increased attention on the experimental medication.
This may have created a risk of unsanctioned medications being sold on the black market online, claiming to be the new drug.
Benjamin Bonenti is an associate research fellow and part of the University of Queensland team researching potential harm in peptides.
"We can say that it is exposing [people who use peptides] to some potentially serious health risks," he told ABC News.
"This drug belongs to the same broad class … as Ozempic-style weight loss drugs, and it acts on multiple hormone pathways that are involved in appetite, metabolism and blood sugar.
"So to double the dose of a drug acting on these pathways, we know for certain with similar drugs like steroids, that it can have drastic effects on the body."
While there is evidence of 'some positive effects' in controlled trials, Bonenti warned that when someone is buying online 'you don't know what you're getting'.
A spokesperson for Eli Lilly previously said in a statement: "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 and cannot legally be sold to the public. 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."
LADBible has approached Eli Lilly for further comment.
Topics: World News, Health
Kit Roberts