People buying the peptide retatrutide online could suffer from side-effects ranging from nausea to pancreatitis
People are risking their health by injecting a highly potent but unapproved weight loss jab called retatrutide, sometimes called the Godzilla of weight loss injections.
The compound works in a similar way to licensed slimming medicines, such as Wegovy and Mounjaro, which mimic gut hormones to quell appetite.
Retatrutide seems to cause even greater weight loss, according to small early-stage trials. But results have not yet been confirmed from larger trials, necessary to show safety before regulators can approve any medicine.
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Retatrutide is not yet approved in any country but it can be bought through online sites from manufacturers in China.
Lib Dem MP Layla Moran, chair of Parliament’s Health and Social Care Select Committee, said the trade of the drug without medical approval, is a “serious threat to public health”. She asked the Medicines and Healthcare Products Regulatory Agency (MHRA) for a “crackdown on the illegal weight-loss jabs trade“.
How is retatrutide different?
Retatrutide is more potent than the two other medicines approved for weight loss: Wegovy and Mounjaro.
Wegovy, the brand name for semaglutide, works by mimicking a gut hormone called GLP-1, and leads to about an average weight loss of 15 per cent after a year. At that point weight tends to plateau even with continued use.
Mounjaro, the brand for tirzepatide, mimics GLP-1 hormone as well as another hormone called GIP. It causes 21 per cent weight loss, again levelling off after a year.
Retatrutide mimics three hormones – GLP-1, GIP and a third one called glucagon, leading to its nickname of triple G.
In the smaller Phase 2 trials completed so far, retatrutide caused up to 24 per cent weight loss after a year, although at that point, people’s weight was still falling, suggesting their final weight loss could be greater.
Medically approved jabs such as Wegovy and Mounjaro have become incredibly popular due to their effectiveness (Photo: Michael Siluk/UCG/Universal Images Group via Getty)
How can it be on sale before approval?
Retatrutide cannot legally be sold for human use without permission from manufacturer Eli Lilly, which owns the patents.
But the chemical formula of retatrutide is publicly available, as with all patented medicines. The compound is a fairly simple molecule called a peptide – a small chain of amino acids – and is being made by small firms, usually in China.
A UK warehouse making retatrutide was also raided last month by the Medicines and Healthcare products Regulatory Agency (MHRA), where tens of thousands of empty weight loss pens and raw chemical ingredients were seized. More than 2,000 unlicensed retatrutide and tirzepatide pens awaiting dispatch to customers were found.
Online, the product is usually advertised as “for research purposes only”.
Often sold as “ret” and “reta”, it may come as powders of the peptide that need to be mixed with sterile water or as vials ready for injection. It seems particularly popular among people seeking to build muscle as well as lose weight.
A spokesperson for Eli Lilly said: “Retatrutide is an investigational medicine, available only in Lilly’s clinical trials. No one can legally sell it for human use. Counterfeit and black-market medicines are untested, unregulated and potentially dangerous — in some cases, deadly.”
What are the dangers?
The weight loss jabs that have recently been approved for use in UK are seen as relatively safe medicines when used under a doctor’s supervision. But they need to be started at a low dose that is gradually raised.
When starting the medicines or when raising the dose, people can get side effects like nausea, vomiting and diarrhoea. Occasionally there have been more serious harms reported, such as pancreatitis, and even some fatalities.
If people are buying a potent weight loss injection from illegal sites, there is a higher risk of side effects, Moran said in a letter to the MHRA. “If people take unlicensed, untested drugs, which are not approved for human use, potentially fatal side-effects, including pancreatitis and gallbladder disorder, are more likely,” she said.
In addition, the products may not be subject to the same quality and safety checks as licensed medicines, said Kiran Jones, pharmacist at Oxford Online Pharmacy. “You could be risking your life. There is no guarantee of what you are putting into your body,” she said.
Can the online sales be stopped?
It’s hard to see how. After a Channel 4 investigation, TikTok and Meta, the parent company of Facebook and Instagram, removed adverts for retatrutide that had been identified. Eli Lilly has said it is taking action against two online sellers, although the firm has not given further details.
But on TikTok, for instance, links for sites that sell retatrutide are easy to find.
In posts where retatrutide users show before-and-after videos of their weight loss, or show themselves injecting the substance, sellers may link to their websites in the comments.
An MHRA spokesperson said: “Buying any medicine from illegal online suppliers significantly increases the risk of receiving falsified or unlicensed products. We work closely with law enforcement partners, customs authorities and online platforms to remove illegal medicines from sale.”
When will legitimate retatrutide be available?
The final Phase 3 trials are due to conclude next May. If the results show the product is safe and effective, it will take at least several more months before UK approval. “If it continues to do well, it could be available by 2027,” said Jones.