Zepbound vs Wegovy: Head-to-Head Trial and Labels Compared
The short answer
Zepbound (tirzepatide) beat Wegovy (semaglutide) in the only head-to-head trial: SURMOUNT-5 found 20.2% weight loss against 13.7% at 72 weeks in adults with obesity and no diabetes. Both are FDA-approved once-weekly injections. Zepbound tops out at 15 mg, Wegovy at 2.4 mg, or 7.2 mg for Wegovy HD.
Zepbound is Eli Lilly's brand name for tirzepatide, which activates the GIP and GLP-1 receptors. Wegovy is Novo Nordisk's brand name for semaglutide, which activates the GLP-1 receptor only. Both are prescription once-weekly injections for weight reduction, and both are FDA approved. This page lines the two US labels up side by side and then looks at the one trial that compared the drugs directly. Everything below is a research reference, not a recommendation to start, stop or switch anything.
Zepbound vs Wegovy at a glance
| What | Zepbound (tirzepatide) | Wegovy (semaglutide) |
|---|---|---|
| Maker | Eli Lilly | Novo Nordisk |
| Receptors | GIP and GLP-1 | GLP-1 |
| Weight indication | Reduce excess body weight and maintain the reduction in adults with obesity, or overweight plus one weight-related condition (Zepbound label, rev. 8/2026) | The same for adults, plus adolescents aged 12 and over with obesity (injection) (Wegovy label, rev. 6/2026) |
| Other indications | Moderate to severe obstructive sleep apnea in adults with obesity | Lower the risk of major cardiovascular events in adults with established heart disease and obesity or overweight; noncirrhotic MASH with stage F2 to F3 fibrosis in adults (accelerated approval) |
| Starting dose | 2.5 mg once weekly for 4 weeks (initiation only) | 0.25 mg once weekly for 4 weeks |
| Escalation | Up to 5 mg after 4 weeks, then 2.5 mg steps, each after at least 4 weeks | Every 4 weeks: 0.5, 1, 1.7, then 2.4 mg |
| Maintenance doses | 5, 10 or 15 mg (sleep apnea: 10 or 15 mg) | Usually 2.4 mg; 7.2 mg (Wegovy HD) where more weight reduction is clinically indicated |
| Highest dose | 15 mg once weekly | 7.2 mg once weekly (Wegovy HD pen); 2.4 mg in the other injection forms |
| Forms | Single-dose pen, single-dose vial, multi-dose vial (4 doses), KwikPen (4 doses) | Single-dose pen, single-dose syringe, FlexTouch pen (4 doses of 2.4 mg), and a once-daily tablet (1.5, 4, 9, 25 mg) |
| Boxed warning | Risk of thyroid C-cell tumors | Risk of thyroid C-cell tumors |
Only Zepbound lists sleep apnea. Only Wegovy lists cardiovascular risk reduction and MASH, and only Wegovy comes as a tablet. Both labels say not to combine the drug with other GLP-1 receptor agonists.
The head-to-head trial: SURMOUNT-5
One trial has compared the two drugs directly. SURMOUNT-5 randomised 751 adults with obesity and no type 2 diabetes to the maximum tolerated dose of tirzepatide (10 or 15 mg) or semaglutide (1.7 or 2.4 mg) once weekly for 72 weeks. It was a phase 3b, open-label trial funded by Eli Lilly (NEJM 2025).
| Outcome at week 72 | Tirzepatide (Zepbound) | Semaglutide (Wegovy) |
|---|---|---|
| Mean weight change | -20.2% (95% CI -21.4 to -19.1) | -13.7% (95% CI -14.9 to -12.6) |
| Mean waist change | -18.4 cm | -13.0 cm |
| Reached 10, 15, 20 and 25% weight loss | More often than semaglutide at every threshold | Less often at every threshold |
| Most common adverse events | Gastrointestinal, mostly mild to moderate, mostly during dose escalation | Gastrointestinal, mostly mild to moderate, mostly during dose escalation |
Two cautions. The trial was open label, so participants and staff knew which drug they were on. And the semaglutide arm topped out at 2.4 mg; the 7.2 mg Wegovy HD dose, which appears in the current label, was not part of the comparison.
Each drug against placebo
The pivotal trials show how each drug performs on its own. They ran for different lengths in different populations, so the percentages are context, not a ranking.
| Trial | Drug and dose | Mean weight change | Placebo |
|---|---|---|---|
| SURMOUNT-1, 72 weeks, 2,539 adults (NEJM 2022) | Tirzepatide 5, 10, 15 mg | -15.0%, -19.5%, -20.9% | -3.1% |
| STEP 1, 68 weeks, 1,961 adults (NEJM 2021) | Semaglutide 2.4 mg | -14.9% | -2.4% |
Side effects on the two labels
Both labels list nausea, diarrhea, vomiting and constipation first. The tables below come from different trials, so use them to see the shape of the profile, not to rank the drugs.
| Reaction | Zepbound 5, 10, 15 mg (placebo) | Wegovy 2.4 mg (placebo) |
|---|---|---|
| Nausea | 25%, 29%, 28% (8%) | 35% (13%) |
| Diarrhea | 19%, 21%, 23% (8%) | Listed as common; rate not reproduced here |
| Vomiting | 8%, 11%, 13% (2%) | 16% (6%) |
| Constipation | 17%, 14%, 11% (5%) | 19% (8%) |
| Hair loss | 5%, 4%, 5% (1%) | 3% (1%) |
| Stopped because of side effects | 6.2% at 15 mg vs 2.6% on placebo (SURMOUNT-1) | 6.8% vs 3.2% on placebo (three trials) |
Zepbound figures are the pooled SURMOUNT-1 and SURMOUNT-2 table in the Zepbound label. Wegovy figures are the 2.4 mg and placebo columns of the 72-week obesity trials table in the Wegovy label; the discontinuation figure is from the label's three 68-week trials. Gastrointestinal events are the main reason people stop either drug. For a closer look at one of them, see tirzepatide and constipation.
Cost and access
List prices, savings programs and insurance coverage for both drugs change often, so we do not print a price here. The current picture is on tirzepatide cost and semaglutide cost without insurance. Storage differs too: see Zepbound storage and Wegovy storage.
Compounded and research-grade versions
Zepbound and Wegovy are the FDA-approved products. Compounded and research-grade tirzepatide and semaglutide are a different category with different legal and quality questions; see compounded tirzepatide and compounded semaglutide. If you work from a vial, the calculators below turn a vial strength, water volume and dose into a syringe mark.
Calculate your draw for tirzepatide or semaglutide
Enter the vial strength, the bacteriostatic water you added and your dose, and get the exact mark on the syringe. Free, no signup.
Open the tirzepatide calculator peptulator.com, the Bureau's independent toolOpen the semaglutide calculator
Same drug, different brand names
Zepbound has a sibling with the same active ingredient: Mounjaro, which is labelled for type 2 diabetes. Wegovy has one too: Ozempic. The pairs are covered in Mounjaro vs Zepbound and Ozempic vs Wegovy. For the molecule-level view, see semaglutide vs tirzepatide and the Zepbound guide.
Not sure which of these you actually need?
Answer five questions about your goal, experience and budget and the Stack Builder shows you a matched research protocol on screen, with the compounds, cycle shape and vendor picks from the six vendors we score.
Build your stack, 2 minutesSee also: Saxenda vs Wegovy, Ozempic vs Mounjaro.
Frequently asked questions
Is Zepbound stronger than Wegovy?
In the one head-to-head trial, SURMOUNT-5, yes: tirzepatide cut body weight by 20.2% at 72 weeks against 13.7% for semaglutide in adults with obesity and no diabetes. The trial was open label, and the semaglutide arm reached 2.4 mg at most, not the 7.2 mg Wegovy HD dose.
What is the difference between Zepbound and Wegovy?
Zepbound contains tirzepatide, which activates GIP and GLP-1 receptors, and is made by Eli Lilly. Wegovy contains semaglutide, which activates the GLP-1 receptor, and is made by Novo Nordisk. Zepbound is also labelled for obstructive sleep apnea; Wegovy is also labelled for cardiovascular risk reduction and MASH and comes as a tablet.
Can you take Zepbound and Wegovy together?
The Zepbound label says coadministration with other tirzepatide-containing products or with any GLP-1 receptor agonist is not recommended, and the Wegovy label says the same about other semaglutide products and GLP-1 receptor agonists.
Do Zepbound and Wegovy have the same side effects?
The profiles are similar: nausea, diarrhea, vomiting and constipation lead both labels, mostly during dose escalation. Both carry a boxed warning for the risk of thyroid C-cell tumors seen in rodents.
Sources (checked 6 November 2026)
- Zepbound prescribing information and Medication Guide, Eli Lilly, revised 8/2026, DailyMed. Checked 6 November 2026.
- Wegovy prescribing information, Novo Nordisk, revised 6/2026. Checked 6 November 2026.
- Aronne et al, Tirzepatide as Compared with Semaglutide for the Treatment of Obesity (SURMOUNT-5), New England Journal of Medicine, 2025. Checked 6 November 2026.
- Jastreboff et al, Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1), New England Journal of Medicine, 2022. Checked 6 November 2026.
- Wilding et al, Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1), New England Journal of Medicine, 2021. Checked 6 November 2026.
Label figures are from the Zepbound label revised August 2026 and the Wegovy label revised June 2026. Labels and trial records change; the leaflet in your box and your prescriber come first. Educational content, not medical advice.