A major head-to-head study found that people lost significantly more weight with Eli Lilly’s diabetes drug Mounjaro compared to Novo Nordisk’s Ozempic, with similar side effects, drop-out rates, and diabetes benefits. Both drugs belong to the GLP-1 class, but Mounjaro, which contains tirzepatide, also marketed as Zepbound for weight loss, has an additional action enhancing its effectiveness. Previous studies had suggested tirzepatide led to more weight loss than semaglutide, sold as Ozempic for diabetes and Wegovy for weight loss at a higher dose.
The new study, published in JAMA Internal Medicine, analyzed data from more than 18,000 patients who started taking one of the two medications between May 2022 and September 2023, using electronic health records from Truveta, a collective of health systems with access to data on over 100 million patients. The study focused on people prescribed these drugs for type 2 diabetes, as tirzepatide was not yet approved for weight loss at the time.
By November of last year, more than half of the participants had stopped taking the medications, with 56% discontinuing tirzepatide and 53% stopping semaglutide, primarily due to gastrointestinal side effects like vomiting and nausea. The study did not indicate whether those who discontinued the drugs regained the weight they had lost.
