Tirzepatide vs semaglutide: how do Zepbound and Mounjaro compare with Wegovy and Ozempic?

How do Semaglutide and Tirzepatide compare?

Status, evidence, formats, routes and prices come from each compound’s page. Prices are the providers’ own listed starting prices, which may exclude a membership fee and change often; they are not DiscoverMedica’s prices.

Does tirzepatide lead to more weight loss than semaglutide?

On average, yes. In SURMOUNT-5, which compared the two directly in adults with obesity and no diabetes, average weight loss at 72 weeks was about 20% with tirzepatide and about 14% with semaglutide. These are trial averages; some people lost much more and some lost little. SURMOUNT-5

Separate placebo-controlled trials point the same way. In STEP 1, semaglutide participants lost about 15% of body weight on average over 68 weeks, versus about 2% on placebo. STEP 1

In SURMOUNT-1, tirzepatide participants lost about 15% to 21% on average over 72 weeks, depending on treatment group, versus about 3% on placebo. SURMOUNT-1

Is Wegovy vs Zepbound the same comparison as Ozempic vs Mounjaro?

It is the same two medicines with different approved uses. Wegovy and Ozempic both contain semaglutide; Zepbound and Mounjaro both contain tirzepatide. Wegovy and Zepbound are approved for weight management, while Ozempic and Mounjaro are approved for type 2 diabetes. The obesity head-to-head trial is SURMOUNT-5; the diabetes one is SURPASS-2. Mounjaro label

In SURPASS-2, adults with type 2 diabetes already on metformin lowered their HbA1c by about 2.0 to 2.3 percentage points over 40 weeks on tirzepatide, versus about 1.9 on semaglutide, and lost about 2 to 5.5 kg more weight, depending on the tirzepatide group. Nausea, diarrhea and vomiting were similarly common with both. SURPASS-2

Ozempic is not approved for weight management; its label covers blood sugar control, and heart and kidney risk reduction, in adults with type 2 diabetes. Ozempic label

How do semaglutide and tirzepatide work differently?

Semaglutide is a lab-made version of GLP-1, a gut hormone that signals fullness and slows stomach emptying. Tirzepatide is a single molecule that switches on two gut-hormone receptors, GIP and GLP-1. Both act on the brain areas that manage appetite, and both help the pancreas release insulin when blood sugar is high. Zepbound label

Are semaglutide and tirzepatide approved for different conditions?

Partly. Both are approved for chronic weight management and for type 2 diabetes. Wegovy is also approved to lower the risk of heart attack and stroke in adults with heart disease and overweight, based on the SELECT trial, where those events were about 20% less common than on placebo. SELECT

Wegovy’s label also covers MASH, a form of fatty liver disease with moderate to advanced scarring, in adults. Wegovy label

Zepbound became the first medication FDA approved for moderate to severe obstructive sleep apnea in adults with obesity, in December 2024. FDA (Dec 2024)

Mounjaro’s label now also includes lowering the risk of heart attack, stroke and heart-related death in adults with type 2 diabetes at high risk of those events. Mounjaro label

Semaglutide also comes as a pill (the Wegovy pill and Rybelsus). Tirzepatide is an injection only. Wegovy label

Do semaglutide and tirzepatide have different side effects?

Mostly no. Both carry the same boxed warning about thyroid C-cell tumors in rodents, and nausea, diarrhea, vomiting and constipation are common with both, especially early in treatment. One difference: the tirzepatide label warns it can make birth control pills less reliable for a period after starting and after each step up in treatment. Zepbound label

Is compounded semaglutide or tirzepatide still an option in 2026?

FDA says no longer as a routine substitute. Tirzepatide left FDA’s shortage list in December 2024 and semaglutide in February 2025, which ended the basis for mass compounding. In April 2026 FDA proposed excluding both from the list of bulk ingredients outsourcing facilities may compound from. FDA (Apr 30, 2026)

In March 2026 FDA warned 30 telehealth companies about how they marketed compounded GLP-1s. FDA (Mar 2026)

FDA says compounded GLP-1s get no FDA review for safety, quality or effectiveness, and it has received hundreds of adverse event reports tied to them. FDA

Semaglutide vs Tirzepatide: questions, answered

Sources

1. SURMOUNT-5: Tirzepatide vs semaglutide for obesity (NEJM 2025)
2. SURPASS-2: Tirzepatide versus semaglutide once weekly in type 2 diabetes (NEJM 2021)
3. STEP 1: Once-weekly semaglutide in adults with overweight or obesity (NEJM 2021)
4. STEP 1 extension: weight regain after stopping semaglutide (Diabetes Obes Metab 2022)
5. SURMOUNT-1: Tirzepatide once weekly for the treatment of obesity (NEJM 2022)
6. SURMOUNT-4: Continued tirzepatide vs placebo for maintenance of weight reduction (JAMA 2024)
7. SELECT: Semaglutide and cardiovascular outcomes in obesity without diabetes (NEJM 2023)
8. FDA (Dec 2024): FDA approves first medication for obstructive sleep apnea
9. DailyMed: Wegovy (semaglutide) prescribing information, revised June 2026
10. DailyMed: Ozempic (semaglutide) injection prescribing information, revised May 2026
11. DailyMed: Zepbound prescribing information
12. DailyMed: Mounjaro (tirzepatide) prescribing information, revised August 2026
13. ADA Standards of Care 2026, Section 8: Obesity and weight management (Guideline Central summary)
14. FDA (Apr 30, 2026): Proposal to exclude semaglutide, tirzepatide and liraglutide from the 503B bulks list
15. FDA (Mar 2026): FDA warns 30 telehealth companies about marketing of compounded GLP-1s
16. FDA: Concerns with unapproved GLP-1 drugs used for weight loss
17. DailyMed: Wegovy prescribing information

Last reviewed October 7, 2026. Every source above was checked on or before that date. Educational information only, not medical advice; it does not replace a conversation with a licensed clinician. DiscoverMedica does not employ clinicians.