Wegovy vs Zepbound: how the two compare

What this guide covers

Both are FDA-approved for weight management, but they are different molecules, and one head-to-head trial put them in the ring. What SURMOUNT-5 found on weight loss, plus side effects, dosing, cost, and how to choose, in plain language. This is patient education, not a substitute for the prescriber who knows your case. Generic names sit next to brand names throughout: semaglutide (Ozempic, Wegovy), tirzepatide (Mounjaro, Zepbound).

Key points

• The short answer. Wegovy and Zepbound are both once-weekly injections approved for chronic weight management, and they are different drugs. Wegovy is semaglutide, a GLP-1 receptor agonist. Zepbound is tirzepatide, which acts on two receptors, GIP and GLP-1. In SURMOUNT-5, the trial that compared them directly, Zepbound produced more average weight loss than Wegovy at 72 weeks. That does not make it automatically right for everyone, because tolerance, cost, insurance coverage, and your clinician's read on your history all matter. Both work.
• Same goal, different molecule. Both are in the incretin family and both are FDA-approved specifically for weight management (that is the difference from Ozempic and Mounjaro, which carry the diabetes indications of the same two molecules). Wegovy is semaglutide and hits the GLP-1 receptor. Zepbound is tirzepatide and hits GLP-1 plus GIP, a second incretin pathway. The leading explanation for why tirzepatide tends to edge ahead on weight is that dual action, though exactly how much the GIP part contributes is still being worked out. The molecule details are in each drug's FDA prescribing information, and we cover them at the molecule level in our semaglutide vs tirzepatide explainer.
• Weight loss, head to head (SURMOUNT-5). Most comparisons stitch together separate trials. SURMOUNT-5 (published in 2025) is the rare direct one: it randomized adults with obesity to tirzepatide or semaglutide at their top tolerated doses and followed them for 72 weeks. Tirzepatide came out ahead, with an average weight reduction around 20% versus roughly 14% for semaglutide. Those line up with what the individual programs showed (STEP-1 for semaglutide, SURMOUNT-1 for tirzepatide). The gap is real, but both are large effects compared with no treatment, which is the honest framing.
• Side effects compared. Because both work largely through the GLP-1 pathway, the side-effect lists look alike: nausea, diarrhea, constipation, and vomiting lead both labels, and all are heaviest right after a dose increase. Across the trials, GI events were common on both and led only a small percentage of people to stop. There is no dependable rule that one is gentler, individual tolerance varies more than the drug-to-drug difference. The management playbook is the same either way, and we cover the big ones for nausea, constipation, and diarrhea.
• Dosing. Both start low and titrate up on a fixed schedule to limit side effects, and both are once-weekly self-injections. Wegovy steps up over roughly 16 to 20 weeks to its 2.4 mg maintenance dose. Zepbound steps from 2.5 mg toward a maximum of 15 mg over a similar stretch. The exact calendar lives in each drug's FDA prescribing information, and prescribers routinely slow it down or hold a dose when side effects are rough. The maximum dose is a ceiling, not a target, the right dose is the lowest one that works for you.

Frequently asked questions