https://www.nejm.org/doi/10.1056/NEJMoa2416394At 72 weeks, the mean percentage decrease in weight was significantly greater with tirzepatide than with semaglutide (20% vs. 14%). Gastrointestinal side effects occurred frequently in both groups but led to discontinuation of treatment in only 3% and 6% of participants in the tirzepatide and semaglutide groups, respectively. Injection-site reactions were more common with tirzepatide than with semaglutide (9% vs. <1%) but didn't cause participants to stop treatment.