Zepbound is tirzepatide, a dual GIP and GLP-1 receptor agonist; Wegovy is semaglutide, a GLP-1-only agonist.
Both are weekly injections approved for chronic weight management in adults with obesity, or overweight with a weight-related condition. The dual-receptor action of tirzepatide is the meaningful pharmacological difference. In Zepbound's label trials, mean weight loss at 72 weeks was 15.0% (5 mg), 19.5% (10 mg), and 20.9% (15 mg) versus 3.1% on placebo. In Wegovy's label trial, mean loss was 14.9% on 2.4 mg versus 2.4% on placebo at 68 weeks. These were not head-to-head studies, so treat the gap as directional. Side effect profiles are similar and mostly gastrointestinal: nausea, vomiting, diarrhea, and constipation, worst during dose escalation. Both carry a boxed warning about thyroid C-cell tumors seen in rodents and are avoided with a personal or family history of medullary thyroid carcinoma or MEN 2. Cost and coverage often decide in practice, since insurers treat the two drugs differently.
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Common questions
What is the difference between Zepbound and Wegovy?
Zepbound and Wegovy are both once-weekly injections approved for chronic weight management, but they contain different drugs. Wegovy is semaglutide, a GLP-1 receptor agonist. Zepbound is tirzepatide, which activates two gut-hormone receptors, GIP and GLP-1, instead of one. That dual action is the core difference, and it shows up in the trial numbers. In the Zepbound label trials, patients on the highest dose (15 mg) lost an average of 20.9% of body weight over 72 weeks, with 10 mg at 19.5% and 5 mg at 15.0%, versus 3.1% on placebo. In the Wegovy label trial, patients on 2.4 mg lost 14.9% over 68 weeks versus 2.4% on placebo. These were separate studies with different populations, so the comparison is directional, not exact. Both share the same main side effects (nausea, vomiting, diarrhea, constipation) and the same boxed warning about thyroid C-cell tumors in rodents. The same molecules treat type 2 diabetes under other names: tirzepatide is Mounjaro, semaglutide is Ozempic. Choice usually comes down to your prescriber's judgment, insurance coverage, and how you tolerate each.