Semaglutide vs tirzepatide: brands, approved uses and the SURMOUNT-5 trial
Four brand names, two active ingredients. Here is which is which, what each label covers, and what the one large head-to-head weight trial reported.
Semaglutide is sold as Ozempic and Wegovy. Tirzepatide is sold as Mounjaro and Zepbound [1][2][3][4]. For weight, the head-to-head trial is SURMOUNT-5: 751 adults with obesity and no type 2 diabetes took the maximum tolerated dose of tirzepatide (10 or 15 mg) or semaglutide (1.7 or 2.4 mg) for 72 weeks. Weight changed by -20.2% on tirzepatide and -13.7% on semaglutide, and waist circumference by -18.4 cm and -13.0 cm [5]. The trial was open-label and funded by Eli Lilly, which makes tirzepatide [5].
Which brand is which
| Brand | Active ingredient | What the US label covers |
|---|---|---|
| Ozempic | Semaglutide [1] | Type 2 diabetes: blood sugar control, cardiovascular and kidney risk [1] |
| Wegovy | Semaglutide [2] | Weight reduction and maintenance, cardiovascular risk in adults with heart disease and obesity or overweight, and MASH with moderate to advanced fibrosis (injection) [2] |
| Mounjaro | Tirzepatide [3] | Type 2 diabetes: blood sugar control and cardiovascular risk in adults at high risk [3] |
| Zepbound | Tirzepatide [4] | Weight reduction and maintenance in adults with obesity, or with overweight and a weight-related condition, and moderate to severe obstructive sleep apnea in adults with obesity [4] |
So Mounjaro and Zepbound are the same medicine under two labels, as are Ozempic and Wegovy. The two molecules work differently: semaglutide activates the GLP-1 receptor, while tirzepatide activates both the GIP and GLP-1 receptors [1][3]. If you came here for “Wegovy vs Mounjaro” or “Zepbound vs Wegovy”, the comparison that matters for weight is Wegovy (semaglutide) against Zepbound (tirzepatide), and the table above gives each label’s approved uses.
What SURMOUNT-5 found
SURMOUNT-5 randomised 751 adults with obesity and without type 2 diabetes, 1 to 1, to the maximum tolerated dose of tirzepatide (10 mg or 15 mg) or semaglutide (1.7 mg or 2.4 mg), injected once weekly for 72 weeks. The main measure was the percent change in weight [5].
| At 72 weeks | Tirzepatide | Semaglutide |
|---|---|---|
| Average weight change | -20.2% (95% CI -21.4 to -19.1) | -13.7% (95% CI -14.9 to -12.6) |
| Average waist change | -18.4 cm | -13.0 cm |
| Weight loss of 10%, 15%, 20% or 25% or more | More likely on tirzepatide | Less likely |
| Most common adverse events | Stomach and bowel, mostly mild to moderate, mainly during dose steps | Same pattern |
How to read that result
- It was open-label and funded by Eli Lilly, the maker of tirzepatide [5].
- Everyone took the maximum tolerated dose, which for semaglutide meant 1.7 mg or 2.4 mg. The Wegovy label also lists a 7.2 mg strength, which this trial did not test [5][2].
- It covers adults with obesity and no type 2 diabetes. For people with type 2 diabetes, see Mounjaro vs Ozempic.
- Averages hide a wide range. Some people on each medicine lost more or less than the average, and the trial cannot say which you will be.
- Weight is one outcome. Labels also differ on uses: Wegovy has a cardiovascular and a MASH indication, and Zepbound has one for sleep apnea [2][4].
The fair summary is that tirzepatide produced greater average weight and waist reductions than semaglutide at the doses tested in this trial [5]. Whether that matters for you depends on your health, your tolerance, your goals and what your prescriber and insurer will do. It is not a recommendation for either.
How the dose steps differ
| Wegovy injection | Zepbound | |
|---|---|---|
| Starting dose | 0.25 mg once weekly [2] | 2.5 mg once weekly for 4 weeks [4] |
| Step schedule | Steps every 4 weeks [2] | Increase in 2.5 mg steps after at least 4 weeks [4] |
| Maintenance for weight | 1.7 mg or 2.4 mg (2.4 recommended), with 7.2 mg an option [2] | 5 mg, 10 mg or 15 mg [4] |
| Missed dose | If the next dose is more than 2 days away, give it as soon as possible; if less, skip it [2] | As soon as possible within 4 days (96 hours); after 4 days, skip it [4] |
Details are on the Wegovy dosing schedule and the tirzepatide dose chart, and the missed dose checker applies each label’s rule.
What the two ingredients share
All four labels carry a boxed warning about thyroid C-cell tumors, and all list stomach and bowel effects among the most common reactions [1][2][3][4]. Neither ingredient is a substitute for medical advice about whether it suits you. The GLP-1 side effects guide lists the trial percentages from each label.
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Frequently asked questions
What is the difference between semaglutide and tirzepatide?
Semaglutide (Ozempic, Wegovy) activates the GLP-1 receptor. Tirzepatide (Mounjaro, Zepbound) activates both the GIP and GLP-1 receptors. Their labels, dose steps and approved uses differ.
Is tirzepatide better than semaglutide for weight loss?
In SURMOUNT-5, a 72-week open-label trial funded by Eli Lilly in 751 adults with obesity and no diabetes, weight fell 20.2% on tirzepatide and 13.7% on semaglutide at the maximum tolerated doses. Which is right for a person is a prescriber’s decision.
Is Mounjaro the same as tirzepatide?
Yes. Mounjaro and Zepbound both contain tirzepatide. Mounjaro is labeled for type 2 diabetes and Zepbound for weight reduction and sleep apnea.
Is Wegovy better than Mounjaro?
They are labeled for different uses. Wegovy is semaglutide for weight and cardiovascular risk, and Mounjaro is tirzepatide for type 2 diabetes. For weight, the closer comparison is Wegovy against Zepbound, covered in SURMOUNT-5.
Do tirzepatide and semaglutide have different side effects?
In SURMOUNT-5 the most common adverse events were stomach and bowel effects in both groups, mostly mild to moderate and mainly during dose steps. Both ingredients carry a boxed warning about thyroid C-cell tumors.
Can I switch from semaglutide to tirzepatide?
The labels do not give a conversion between them. Switching, and the dose to start at, is for your prescriber.
Sources
- OZEMPIC (semaglutide) injection: full prescribing information. Novo Nordisk, revised 05/2026. Sections 2.1 and 2.2 (administration, missed dose, dosage) and 3 (strengths).
- WEGOVY (semaglutide) injection and tablets: full prescribing information. Novo Nordisk, revised 06/2026. Sections 2.1 to 2.5 (administration, dosage, missed doses, switching) and 3 (strengths).
- MOUNJARO (tirzepatide) injection: full prescribing information. Eli Lilly and Company, revised 08/2026. Sections 2.1 and 2.2 (dosage, missed doses, administration) and 3 (strengths).
- ZEPBOUND (tirzepatide) injection: full prescribing information. Eli Lilly and Company, revised 08/2026. Sections 2.1 to 2.4 (dosage, missed dose, administration) and 3 (strengths).
- Tirzepatide as Compared with Semaglutide for the Treatment of Obesity (SURMOUNT-5). Aronne LJ et al. New England Journal of Medicine, 2025 (PubMed 40353578, doi 10.1056/NEJMoa2416394). Abstract read through Europe PMC on 22 October 2026. Phase 3b, open-label, 751 adults with obesity and no type 2 diabetes, 72 weeks. Funded by Eli Lilly, which makes tirzepatide.
How we write these. Every dose, interval and window above comes from the manufacturer’s US prescribing information, checked on 6 October 2026, and links to it. Labels are updated, so check the current label or ask your pharmacist before you act. Nerra is made by Hicham Zaidi. We do not sell any medicine and are not affiliated with any manufacturer. If you spot an error, tell us through the Nerra support page.
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