Enlarge (credit: https://www.uschemlabs.com/product/semaglutide-2mg-5-vials/)

Buying counterfeit weight loss drugs from illegal online pharmacies that don't require prescriptions is, in fact, a very bad idea, according to a study published Friday in JAMA Network Open.

The counterfeit drugs are sold as equivalents to the blockbuster semaglutide drugs, Ozempic and Wegovy, which are prescription only. When researchers got their hands on three illegal versions, they found that the counterfeit drugs had low-purity semaglutide, had dosages that exceeded the labeled amount, and one had signs of bacterial contamination.

The three substandard drugs tested came from three different illegal online pharmacies, which sold them as generic semaglutide drugs for weight loss, appetite suppression, diabetes, and cardiovascular health. However, the researchers, led by scientists at the University of California, San Diego, and the University of Pécs in Hungary, had initially tried purchasing counterfeit drugs from six such sellers.

Enlarge / Wegovy is an injectable prescription weight-loss medicine that has helped people with obesity. (credit: Getty | Michael Siluk)

The US Food and Drug Administration has approved two injectable versions of the blockbuster weight-loss and diabetes drug semaglutide (Wegovy and Ozempic). Both come in pre-filled pens with pre-set doses, clear instructions, and information about overdoses. But, given the drugs' daunting prices and supply shortages, many patients are turning to imitations—and those don't always come with the same safety guardrails.

In an alert Friday, the FDA warned that people are overdosing on off-brand injections of semaglutide, which are dispensed from compounding pharmacies in a variety of concentrations, labeled with various units of measurement, administered with improperly sized syringes, and prescribed with bad dosage math. The errors are leading some patients to take up to 20 times the amount of intended semaglutide, the FDA reports.

Though the agency doesn't offer a tally of overdose cases that have been reported, it suggests it has received multiple reports of people sickened by dosing errors, with some requiring hospitalizations. Semaglutide overdoses cause nausea, vomiting, abdominal pain, fainting, headache, migraine, dehydration, acute pancreatitis, and gallstones, the agency reports.

Enlarge / Ozempic is a GLP-1 drug for adults with type 2 diabetes. (credit: Getty | Steve Christo)

For patients with Type 2 diabetes, taking one of the new GLP-1 drugs, such as Ozempic, is associated with lower risks of developing 10 out of 13 obesity-associated cancers as compared with taking insulin, according to a recent study published in JAMA Network Open.

The study was retrospective, capturing data from over 1.6 million patients with Type 2 diabetes but no history of obesity-associated cancers prior to the study period. Using electronic health records, researchers had follow-up data for up to 15 years after the patients started taking either a GLP-1 drug, insulin, or metformin between 2008 and 2015.

This type of study can't prove that the GLP-1 drugs caused the lower associated risks, but the results fit with some earlier findings. That includes results from one trial that found a 32 percent overall lower risk of obesity-associated cancers following bariatric surgery for weight loss.