The most powerful weight-loss drug yet is not yet approved, but its black market could already be turning deadly

An experimental drug called retatrutide is poised to become the most effective weight-loss drug ever seen. Unfortunately, some people appear to suffer serious and even fatal complications from taking copied versions of the as-yet-unapproved drug.

The Food and Drug Administration has received at least two reports of deaths linked to illicit retatrutide this year, according to documents first revealed by CBS News this week. While it is unclear whether counterfeit retatrutide is responsible for these deaths, these are just the latest reports to suggest that such products may be dangerous.

“It’s concerning because of the failure of our drug approval process in the United States of America,” Pieter Cohen, an associate professor at Harvard Medical School, told CBS News on Monday.

Retatrutide bootleg

Retatrutide is developed by the Eli Lilly company. This is the latest version of obesity and diabetes drugs that harness certain types of hunger-related hormones like GLP-1. Retatrutide specifically mimics GLP-1, GIP and the glucagon hormone.

So far, large-scale clinical trials have demonstrated that retatrutide may have the greatest potency of any obesity drug developed to date, with weight loss rates of up to 30%, a level comparable to that of gold-standard bariatric surgeries. Given these results, the FDA and other regulatory agencies will almost certainly grant Eli Lilly approval for retatrutide as early as this year.

The approval of earlier GLP-1 drugs like semaglutide (Ozempic and Wegovy) and tirzepatide (Mounjaro and Zepbound) was quickly followed by the emergence of a gray and black market for these drugs. This is a market that has been fueled by, among other factors, the high list prices and limited insurance coverage of GLP-1s. People have often been able to purchase compounded and/or counterfeit versions of these drugs at a much cheaper price than the genuine article, although the costs of the genuine products have decreased significantly over time.

This underground market now also extends to retatrutide. Although the drug is not approved anywhere, some companies are already distributing and selling it and other unregulated peptides, often produced in China, to people all over the world. And the two deaths reported to the FDA this year appear to be linked to black market retatrutide.

The deaths were reported to the FDA through its adverse event reporting system, which is primarily intended to monitor the safety of approved drugs once they are made public. CBS News obtained the reports through a Freedom of Information Act request.

The first death was documented by a healthcare professional in July. It involved a 41-year-old obese woman who suffered a cardiac arrest after taking retatrutide from an “unreliable source”. The second was reported last month, involving a 49-year-old patient who died from severe dehydration, malnutrition and cardiac arrest. The patient allegedly obtained retatrutide from an online peptide seller, on the advice of a registered nurse.

The dangers of the GLP-1 black market

It is important to note that these reports alone cannot prove whether a drug is responsible for a specific adverse event or a person’s death. Rather, they aim to detect potential security signals that can be further investigated.

At the same time, other researchers and countries have reported similar cases of serious complications linked to retatrutide on the black market. Last month, Australian officials reported that a patient had torn his esophagus due to constant vomiting. And earlier last May, doctors detailed the case of a man who suffered from incessant diarrhea for a week and sent him to the hospital.

Given the lack of attention paid to these underground products, it is unclear whether these people were actually taking retatrutide. Other counterfeit GLP-1s seized by authorities sometimes contain insulin or other medications. But even if people take the genuine article, it’s also possible that they would take much higher doses than those used in clinical trials, which would obviously increase the risks of serious side effects.

No drug is without risks, even after it has been approved. But people looking for a weight loss advantage from black market retatrutide are playing a very dangerous game.