Wegovy vs Zepbound

Wegovy (semaglutide, Novo Nordisk) and Zepbound (tirzepatide, Eli Lilly) are the two prescription injections that the FDA has approved specifically for chronic weight management in adults with obesity or overweight plus a weight-related condition. They are the most direct apples-to-apples comparison in the GLP-1 weight-loss conversation.

Despite being prescribed for the same purpose, they are not the same drug. Wegovy is a selective GLP-1 receptor agonist. Zepbound is a dual GIP / GLP-1 receptor agonist. That structural difference shows up in the trial results: in their respective pivotal studies, Zepbound produced a larger mean weight loss than Wegovy, and a 2025 head-to-head trial (SURMOUNT-5) again favored tirzepatide.

That doesn't make the choice automatic. Coverage, side effect tolerance, dose ceiling, and personal history matter as much as the headline percentage.

At a glance

How they're alike

Both are once-weekly subcutaneous injections in pre-filled pen devices. Both work primarily by slowing gastric emptying, signaling satiety to the brain, and reducing the food noise that drives between-meal grazing. Both are titrated upward over roughly four to five months to reach a maintenance dose, so the first half-year often involves dose changes.

The on-label indication is essentially the same: chronic weight management in adults with a BMI of 30 or higher, or 27 with a weight-related condition such as hypertension, dyslipidemia, or type 2 diabetes. Both labels carry a boxed warning about thyroid C-cell tumors (extrapolated from rodent studies) and standard cautions about pancreatitis and gallbladder events.

Side effects rhyme across the two drugs. Nausea, constipation, diarrhea, fatigue, and reflux are common, especially during dose escalation. Both drugs perform better when paired with a structured diet and movement plan than when used alone.

How they're different

Mechanism is the upstream difference. Wegovy hits one receptor (GLP-1). Zepbound hits two (GIP and GLP-1). The added GIP activity contributes to insulin sensitivity and, in trials so far, larger weight reductions at the top dose.

Trial numbers reflect that. STEP 1 reported a mean body weight reduction of about 14.9 percent at 68 weeks on Wegovy 2.4 mg. SURMOUNT-1 reported about 20.9 percent at 72 weeks on Zepbound 15 mg. SURMOUNT-5, the first direct head-to-head, again showed tirzepatide ahead of semaglutide on weight loss endpoints. Individual variation is large, but the population averages tilt in Zepbound's favor.

Dose ranges and titration differ. Wegovy steps up through 0.25 → 0.5 → 1.0 → 1.7 → 2.4 mg. Zepbound steps up through 2.5 → 5 → 7.5 → 10 → 12.5 → 15 mg. The Zepbound ladder has more steps, which gives prescribers more room to slow titration if side effects flare. Cost, insurance handling, and savings programs vary by manufacturer.

Which one is right for you?

If your insurance covers both, the larger trial-average weight loss is one reason patients and clinicians often start the conversation with Zepbound. But "covers both" is the rare case. More often the choice is made by what your formulary will pay for, what your pharmacy can fill, and which manufacturer savings program you qualify for.

Personal factors matter too. People who did well on Ozempic in the past sometimes prefer Wegovy because they know how their body handles semaglutide. People who have hit a plateau on semaglutide sometimes switch to Zepbound for the additional headroom. Side effect tolerance, especially during titration, is highly individual. Bring honest information about your goals, budget, and prior experience into the conversation with your prescriber.

Common questions

Keep exploring

Browse all GLP-1 guides or compare tirzepatide and semaglutide in depth.