As weight-loss drugs like GLP-1 receptor agonists explode in popularity, knock-offs of up-and-coming meds are hitting the streets far faster than their legitimate versions can gain regulatory approval.

In recent months, a black market version of the nascent weight-loss drug retatrutide has surged into strip mall health spas and social media marketplaces alike. According to Axios, the drug hasn’t even been submitted to the Food and Drug Administration for review, let alone approved, alarming public health experts around the US.

Developed by the pharmaceutical giant Eli Lilly, retatrutide is a triple-hormone-receptor agonist, meaning it activates three metabolic pathways: the well-known GLP-1, as well as two other specialized cell proteins known as GIP and glucagon receptors.

The combination of these three hormones is meant to reduce the patient’s appetite, control the body’s insulin levels, and increase the amount of calories burned.

For anyone interested in weight-loss drugs, that triple-threat might sound like a no-brainer.

Early results show some promise, per Lilly’s own investor release, supposedly resulting in an average weight loss of 71.2 pounds in early trials. But early investor statements should be taken with a grain of salt, especially where a for-profit drug conglomerate is concerned.

As for any current versions of retatrutide, Lilly doesn’t plan to submit its application to the FDA until 2027 — making any currently-available version of the drug an extremely dubious proposition. Though medical researchers can theoretically source retatrutide from lab supply companies, no provider in the US is authorized to prescribe the stuff for weight loss.

If you do go for the black market option, the consequences should be severe. On Monday, ABC Australia reported that use of a counterfeit vial of retatrutide led to a severe liver injury for one unfortunate patient. The damages may stem from a “contaminated batch” of unregulated retatrutide, but as clinical tests around the drug are in their very early stage, Australian health authorities can’t say for sure.

What they can be sure of is that use of unregulated peptides comes with some gnarly risks. Marie Sinclair, a liver transplant specialist who treated the patient in question, said that users “may become yellow or jaundiced, which is very frightening for patients, and they can become very unwell.”

So far, Eli Lilly has filed six lawsuits against various med spas, a pharmacy, and other drug vendors for selling black market versions of the drug, per Axios.

“Promising isn’t the same as proven,” said John Hertig, a pharmaceutical practice lecturer and chair at the Collaborative for Evidence-Based Medicines in a statement. “Excitement and consumer demand for a new therapy should not allow commercial availability to race ahead of the evidence needed to establish how a medicine can be used safely and effectively.”

“Patients deserve treatments supported by rigorous evidence,” Hertig continued, “not unauthorized products marketed before the science is complete.”

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