Wegovy vs. Mounjaro: different molecules, different labels

Two things differ here, and keeping them apart makes the comparison useful.

The molecule. Wegovy is semaglutide, which activates the GLP-1 receptor. Mounjaro is tirzepatide, which activates both the GLP-1 and GIP receptors. Both are weekly injections that reduce appetite and slow stomach emptying.

The label. Wegovy treats obesity, or overweight with a weight-related condition, in adults and in teens 12 and older. It also lowers cardiovascular risk in adults with heart disease and excess weight, and treats MASH liver disease with moderate to advanced fibrosis. It comes as an injection (up to 2.4 mg weekly, or 7.2 mg as Wegovy HD) and as a 25 mg daily pill. Mounjaro treats type 2 diabetes in adults and in children 10 and older, from 2.5 mg up to 15 mg weekly.

The fairer pairs. For weight, compare Wegovy with Zepbound, which is tirzepatide under a weight-management label. For diabetes, compare Ozempic with Mounjaro. Comparing Wegovy with Mounjaro mixes both questions at once.

No trial has compared Wegovy with Mounjaro under their own labels. The molecules have been compared for weight and for diabetes.

For weight: SURMOUNT-5 (NEJM, 2025). In 751 adults with obesity and no diabetes, people took the highest tolerated dose of tirzepatide or semaglutide. At 72 weeks, mean weight change was −20.2% on tirzepatide and −13.7% on semaglutide, or 22.8 kg against 15.0 kg, per the American College of Cardiology. About 31% on tirzepatide lost at least a quarter of their body weight, versus about 16% on semaglutide.

The higher Wegovy dose. STEP UP (Lancet Diabetes & Endocrinology, 2025) reported −18.7% at 72 weeks on semaglutide 7.2 mg. It had no tirzepatide arm, so its result cannot be set directly against SURMOUNT-5.

For diabetes: SURPASS-2 (NEJM, 2021) found tirzepatide lowered HbA1c more than semaglutide 1 mg at every dose over 40 weeks.

Heart outcomes. SELECT (NEJM, 2023) showed a 20% lower risk of major cardiovascular events on Wegovy 2.4 mg in people with heart disease and overweight but no diabetes. SURPASS-CVOT (NEJM, 2025) found tirzepatide noninferior to dulaglutide in people with diabetes and heart disease, and Mounjaro's 2026 label now carries that heart indication. The two cover different people: Wegovy's is for overweight without diabetes, Mounjaro's for high-risk adults with type 2 diabetes.

Gut effects dominate on both, with most trouble during dose increases. The label figures come from different populations, so read them with care.

Wegovy's prescribing information lists nausea in 44% of adults at 2.4 mg and diarrhea in 30%. Mounjaro's lists nausea in 12–18% and diarrhea in 12–17% across 5 to 15 mg in diabetes trials. That gap reflects different trials, not proof that Mounjaro is gentler. In SURMOUNT-5, which gave both molecules to similar people, gut side effects made 2.7% on tirzepatide and 5.6% on semaglutide stop treatment.

Each label has its own points. Wegovy's reports dysesthesia, a tingling or burning skin sensation, in 22% of people on 7.2 mg. Mounjaro's advises a backup to birth control pills for 4 weeks after starting and after each increase. Low blood sugar is a bigger concern on Mounjaro, which is often paired with insulin or a sulfonylurea.

Shared risks include pancreatitis, gallbladder disease and kidney injury from dehydration. Both carry the boxed warning on thyroid C-cell tumors seen in rodents.

Wegovy fits people whose goal is weight management or heart-risk reduction without diabetes. It also fits teenagers 12 and older with obesity and adults with MASH. Of the two, it is the only one with a weight label and a pill form.

Mounjaro fits people with type 2 diabetes who need stronger glucose control, including children 10 and older, and high-risk adults with diabetes who also want its heart-risk indication. Weight loss often comes with it, but weight is not its approved purpose.

If you want tirzepatide for weight, ask about Zepbound rather than Mounjaro. Coverage for Mounjaro without diabetes is usually refused. Tirzepatide had the larger weight effect in SURMOUNT-5. Wegovy, though, has outcome evidence from SELECT behind a heart indication that tirzepatide's weight label lacks.

Neither fits people with a personal or family history of medullary thyroid carcinoma or MEN 2, or with severe gastroparesis.

If cost is the barrier, say so. Compounded semaglutide and tirzepatide are available, but they are not FDA-approved and have no trials of their own. A prescriber can explain what that trade-off means for you.