Zepbound vs. Ozempic: two molecules, two approved uses

Molecule. Zepbound contains tirzepatide, which activates two gut-hormone receptors, GIP and GLP-1. Ozempic contains semaglutide, which activates GLP-1 alone. Both slow digestion and curb appetite.

Approved uses. Zepbound (Eli Lilly, approved November 2023) is for adults with obesity, or overweight with a weight-related condition. Since December 2024 it also treats moderate to severe obstructive sleep apnea in adults with obesity. Ozempic (Novo Nordisk, 2017) is for adults with type 2 diabetes. It covers blood sugar control, lower heart attack and stroke risk with heart disease, and slower kidney decline with chronic kidney disease. It is not approved for weight loss.

Doses. Zepbound starts at 2.5 mg weekly and rises by 2.5 mg every four weeks to a 5, 10 or 15 mg maintenance dose. Ozempic runs 0.25 mg up to 2 mg weekly.

Forms. Zepbound comes as single-dose pens, single-dose and multi-dose vials, and a four-dose KwikPen. Ozempic comes in multi-dose pens, and there is now an Ozempic pill for diabetes.

For reference, tirzepatide's diabetes brand is Mounjaro, and semaglutide's weight brand is Wegovy.

No trial has compared Zepbound with Ozempic as brands. Two trials compared the molecules, each from a different angle.

SURPASS-2 (NEJM, 2021) is the closest match on Ozempic's side. It randomized 1,879 adults with type 2 diabetes to tirzepatide 5, 10 or 15 mg or to semaglutide 1 mg, an Ozempic dose, for 40 weeks. HbA1c fell 2.01 to 2.30 percentage points on tirzepatide and 1.86 on semaglutide. People on tirzepatide lost 1.9 to 5.5 kg more than those on semaglutide, depending on dose.

SURMOUNT-5 (NEJM, 2025) is the closest match on Zepbound's side. In 751 adults with obesity and no diabetes, tirzepatide at the highest tolerated dose produced a mean weight change of −20.2% at 72 weeks, against −13.7% on semaglutide. Waist size fell 18.4 cm versus 13.0 cm, per the American College of Cardiology's summary.

Zepbound's own trial, SURMOUNT-1 (NEJM, 2022), reported −15.0%, −19.5% and −20.9% at 5, 10 and 15 mg over 72 weeks, versus −3.1% on placebo.

Two caveats apply. SURMOUNT-5 used Wegovy-level semaglutide doses, not Ozempic's. SURPASS-2 did not test Ozempic's 2 mg ceiling.

Both drugs cause the same family of gut effects, mostly while doses are rising. The label figures below come from different trials, so compare them with care.

Zepbound's prescribing information reports nausea in 25–29% of people across its doses, diarrhea in 19–23%, vomiting in 8–13% and constipation in 11–17%. Ozempic's reports nausea in 15.8% at 0.5 mg and 20.3% at 1 mg, with vomiting in 5% and 9.2%. In SURMOUNT-5, where the two molecules were compared directly, 2.7% of tirzepatide users and 5.6% of semaglutide users stopped because of gut side effects, per the American College of Cardiology.

Zepbound's label also lists injection-site reactions, hypersensitivity reactions, hair loss and reflux among its common effects. Serious risks overlap: pancreatitis, gallbladder disease, kidney injury from dehydration and diabetic retinopathy complications. Ozempic is more often paired with insulin or a sulfonylurea, which raises the chance of low blood sugar. The thyroid C-cell tumor boxed warning, based on rodent studies, appears on both labels.

Zepbound fits adults whose main goal is weight management, including people with obesity-related obstructive sleep apnea. It showed the larger weight effect in direct comparison. It is also the one to ask about if you do not have diabetes, because weight management is its approved use.

Ozempic fits adults with type 2 diabetes, especially those with heart disease or chronic kidney disease, where it holds approvals Zepbound lacks. If you have diabetes and want tirzepatide, the diabetes-labeled product is Mounjaro rather than Zepbound.

If weight is the goal but you prefer semaglutide, the matching product is Wegovy, not Ozempic.

Neither fits anyone with a personal or family history of medullary thyroid carcinoma or MEN 2, and neither is recommended in severe gastroparesis. On pregnancy, the labels differ: Zepbound's says to stop once pregnancy is recognized, while Ozempic's allows use only if the benefit justifies the risk and advises stopping two months before a planned pregnancy.

Coverage usually follows the label. A claim for Ozempic without diabetes is often denied. A claim for Zepbound may need proof of obesity, or of sleep apnea with obesity. Check your plan's rules before you choose.