Eli Lilly hits out against the use of Mounjaro, Zepbound for ‘cosmetic weight loss’

Eli Lilly is taking a stand against the use of its blockbuster GLP-1 receptor agonist for “cosmetic weight loss.” In an open letter, the drugmaker came out against the use of Mounjaro and Zepbound for cosmetic weight loss after becoming “aware of certain practices relating” to the medicines.

Evidence that tirzepatide, the active ingredient in the diabetes drug Mounjaro and weight loss medicine Zepbound (which both use the same ingredient), and Novo Nordisk’s rival GLP-1 receptor agonist can help people with overweight and obesity shed pounds has sparked a frenzy. Celebrities such as Elon Musk and Oprah Winfrey have spoken about their use of the drugs, spurring interest in their use outside of the FDA-approved indication.    

Mounjaro, while containing the same active ingredient as Zepbound, is only indicated for use in type 2 diabetes. Use of Zepbound is restricted to people with obesity, as measured by their BMI, or overweight plus at least one weight-related comorbidity.

The stories of celebrity users of GLP-1 receptor agonists could encourage use of the medicines outside of their indications. Sharon Osbourne, for example, said she lost too much weight on Novo’s diabetes drug Ozempic and “didn’t want to go this thin.” Lilly is aware of “certain practices” related to Mounjaro and Zepbound and posted the open letter to set out its position.

“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,” Lilly wrote. “Lilly does not promote or encourage use of Mounjaro, Zepbound, or any Lilly medicines outside of a medicine’s FDA-approved indication.”

The drugmaker goes on to warn of the risks of using compounded tirzepatide. Compounding pharmacies began selling tirzepatide and Novo’s semaglutide as demand for the approved drugs exceeded demand. Lilly and Novo have both taken legal action against compounding pharmacies. 

Lilly opened another front in its pushback against compounding in the open letter, warning that products made by pharmacies “may expose patients to potentially serious health risks.” The drugmaker said it “is extremely concerned” that its tests have shown some compounded tirzepatide contained “high amounts of impurities, and, in at least one instance, was actually nothing more than sugar alcohol.”