INDIANAPOLIS (NewsNation) — American pharmaceutical company Eli Lilly said in a recent open letter that the company is against the “use of its medicines for cosmetic weight loss.”

“Lilly Stands Against the Use of its Medicines for Cosmetic Weight Loss: Mounjaro and Zepbound are indicated for the treatment of serious diseases; they are not approved for – and should not be used for – cosmetic weight loss,” the letter read in part.

The letter comes as drugs like Ozempic and Wegovy have become popular among those trying to manage their weight.

While Zepbound is a weight loss drug, Eli Lilly says it is only for obese or overweight adults who have “at least one weight-related additional condition,” like high blood pressure, high cholesterol, type 2 diabetes mellitus, obstructive sleep apnea or heart disease.

As the popularity of diabetes drugs Mounjaro, Ozempic and Wegovy for weight loss has skyrocketed, patients have reported severe health problems, some even fatal.

Dr. Michael Feiz, a bariatric surgeon, believes overprescribing may be contributing to the problem.

“It’s important to understand that the medications do a lot of good. These medications aren’t bad. If they’re used improperly, if they’re used irresponsibly, they can be harmful,” Feiz said on “CUOMO” in November. “As we release these medications, we need to become more responsible in the way that they’re used.”

The drugs tirzepatide in Zepbound and Mounjaro and semaglutide in Wegovy and Ozempic work by mimicking hormones that kick in after people eat to regulate appetite and the feeling of fullness. Both imitate a hormone called glucagon-like peptide-1, known as GLP-1. Tirzepatide targets a second hormone called glucose-dependent insulinotropic polypeptide, or GIP.

NewsNation’s Tyler Wornell contributed to this report.