The exorbitant cost of the current trend in weight loss drugs has driven some diehard dieters to try generic versions of the drugs compounded by pharmacists. But experts warn that while these copycat versions of Ozempic and Wegovy may have a more reasonable price tag, they may not be the real deal.

According to NBC News, Novo Nordisk, the sole manufacturer of Ozempic and Wegovy, holds the patent on semaglutide, the active ingredient in these medications approved for the treatment of type 2 diabetes and long-term obesity. Ozempic has only been approved to treat diabetes, while Wegovy got the green light from the Food and Drug Administration (FDA) to treat adults with obesity in 2021. The pharmaceutical company said in a statement that it does not provide semaglutide to compounding pharmacies, leading some experts to question where they are sourcing the drug and whether it is semaglutide at all.

“That’s the million-dollar question,” said Dr. Fatima Cody, an obesity specialist at Massachusetts General Hospital in Boston and advisor to Novo Nordisk. Compounding pharmacies specialize in creating tailor-made medications for people using the active ingredients in drugs. In this case, the active ingredient is semaglutide.

Compounded drugs, even if they contain FDA-approved ingredients, are not FDA approved by themselves, meaning they are not regulated, warns Benjamin Jolley, a pharmacist and owner of Jolley’s Compounding Pharmacy in Salt Lake City. The FDA allows compounding pharmacists to supply medications when commercially produced drugs aren’t available or the dosage isn’t suitable for a patient.

Compounded versions of Ozempic and Wegovy are growing in popularity, say weight loss experts, who question if the pharmacies who are creating them are being fully transparent about the ingredients.

Jolley told NBC News it is possible that compounding pharmacists could be giving people semaglutide sodium, a cheaper and modified version of the compound that is intended only for research purposes. Semaglutide sodium isn’t approved by the FDA which would make selling the product illegal, the pharmacist added. Jolley said that compounding pharmacists could also be buying semaglutide from wholesalers and then mixing it with other drug ingredients after separating it into smaller doses.

The lack of transparency in what the compounded versions of Ozempic and Wegovy contain may be a safety issues.

“What I’m telling patients is to be very careful when considering any form of compounded semaglutide or compounded tirzepatide, which is another medication we’re seeing currently offered in compounded form,” said Dr. Chris McGowan, a national leader in weight loss programs from Cary, North Carolina. Tirzepatide is a diabetes drug from Eli Lilly that also can trigger weight loss.