Ozempic vs Mounjaro: Semaglutide vs Tirzepatide Compared
The short answer
Ozempic (semaglutide) and Mounjaro (tirzepatide) are both once-weekly injections labelled for type 2 diabetes. In the head-to-head SURPASS-2 trial, Mounjaro lowered HbA1c by 2.01 to 2.30 points against 1.86 for Ozempic 1 mg over 40 weeks, and led to more weight loss. Neither label lists weight loss as an indication.
Ozempic and Mounjaro are the two best-known once-weekly injections for type 2 diabetes. Ozempic is semaglutide from Novo Nordisk, which activates the GLP-1 receptor. Mounjaro is tirzepatide from Eli Lilly, which activates the GIP and GLP-1 receptors. Unlike most brand comparisons, these two have been tested head to head in a large trial. This page sets the two US labels side by side and then reads that trial. It is a research reference, not medical advice.
Ozempic vs Mounjaro at a glance
| What | Ozempic (semaglutide) | Mounjaro (tirzepatide) |
|---|---|---|
| Maker | Novo Nordisk | Eli Lilly |
| Receptors | GLP-1 | GIP and GLP-1 |
| Label covers | Glycemic control in adults with type 2 diabetes; lowering major cardiovascular event risk in adults with type 2 diabetes and established heart disease; lowering the risk of sustained eGFR decline, end-stage kidney disease and cardiovascular death in adults with type 2 diabetes and chronic kidney disease (Ozempic label, rev. 5/2026) | Glycemic control in adults and in children aged 10 and over with type 2 diabetes; lowering major cardiovascular event risk in adults with type 2 diabetes at high risk (Mounjaro label, rev. 8/2026) |
| Starting dose | 0.25 mg once weekly for 4 weeks | 2.5 mg once weekly |
| Escalation | 0.5 mg after 4 weeks; 1 mg after at least 4 weeks on 0.5 mg; 2 mg after at least 4 weeks on 1 mg, each only if more glycemic control is needed | 2.5 mg increments after at least 4 weeks on the current dose, if more glycemic control is needed |
| Highest dose | 2 mg once weekly | 15 mg once weekly in adults; 10 mg in pediatric patients |
| Boxed warning | Risk of thyroid C-cell tumors | Risk of thyroid C-cell tumors |
The numbers are not comparable across the two columns: 2 mg of semaglutide and 15 mg of tirzepatide are different molecules at different potencies. Compare outcomes, not milligrams. Neither label lists weight reduction as an indication; that is the job of Wegovy and Zepbound, covered further down.
The head-to-head trial: SURPASS-2
SURPASS-2 randomised 1,879 adults with type 2 diabetes to tirzepatide 5, 10 or 15 mg or semaglutide 1 mg, once weekly for 40 weeks. It was open label and funded by Eli Lilly (NEJM 2021). Mean baseline HbA1c was 8.28% and mean weight 93.7 kg.
| Outcome | Tirzepatide 5 mg | Tirzepatide 10 mg | Tirzepatide 15 mg | Semaglutide 1 mg |
|---|---|---|---|---|
| HbA1c change (percentage points) | -2.01 | -2.24 | -2.30 | -1.86 |
| Difference from semaglutide | -0.15 | -0.39 | -0.45 | Reference |
| Extra weight loss vs semaglutide | 1.9 kg | 3.6 kg | 5.5 kg | Reference |
| Event | Tirzepatide, 5 to 15 mg | Semaglutide 1 mg |
|---|---|---|
| Nausea | 17% to 22% | 18% |
| Diarrhea | 13% to 16% | 12% |
| Vomiting | 6% to 10% | 8% |
| Serious adverse events | 5% to 7% | 3% |
| Hypoglycemia (glucose below 54 mg/dL) | 0.2% to 1.7% | 0.4% |
Tirzepatide was non-inferior and superior to semaglutide on HbA1c at every dose. Three cautions. The trial was open label. The semaglutide arm used 1 mg, not the 2 mg dose that is now on the Ozempic label. And the trial measured blood sugar in people with diabetes, so it says little about how either drug performs for weight loss in people without diabetes; for that, see Zepbound vs Wegovy.
Side effects on the two labels
Nausea, vomiting, diarrhea, abdominal pain and constipation lead both labels, mostly during dose escalation. The percentages below come from different placebo-controlled trials, so use them to see the shape of each profile, not to rank the drugs.
| Reaction | Ozempic 0.5 mg, 1 mg (placebo) | Mounjaro 5, 10, 15 mg (placebo) |
|---|---|---|
| Nausea | 15.8%, 20.3% (6.1%) | 12%, 15%, 18% (4%) |
| Vomiting | 5.0%, 9.2% (2.3%) | 5%, 5%, 9% (2%) |
| Diarrhea | 8.5%, 8.8% (1.9%) | 12%, 13%, 17% (9%) |
| Constipation | 5.0%, 3.1% (1.5%) | 6%, 6%, 7% (1%) |
Sources: Table 1 of the Ozempic label (placebo-controlled trials in type 2 diabetes, about 260 patients per arm) and the Mounjaro label placebo-controlled pool. The weekly doses differ, so the columns do not line up dose for dose.
Which one is for weight loss?
Neither. The same two active ingredients carry weight-loss labels under other names: semaglutide as Wegovy and tirzepatide as Zepbound. The Ozempic label does report weight changes in its diabetes trials (in the 30-week monotherapy trial, -3.8 kg on 0.5 mg and -4.7 kg on 1 mg against -1.2 kg on placebo), but weight reduction is not an indication. The brand pairs are covered in Ozempic vs Wegovy and Mounjaro vs Zepbound. For the molecule-level comparison across both uses, see semaglutide vs tirzepatide.
Storage and cost
Prices and coverage move often, so none are printed here; the cost picture is on tirzepatide cost and semaglutide cost without insurance. Storage limits differ by pen and form: see Ozempic storage and Mounjaro storage.
Research-grade versions
Neither brand name applies to compounded or research-grade semaglutide and tirzepatide, which are a different category with different legal and quality questions; see compounded semaglutide and compounded tirzepatide. If you work from a vial, the calculators turn vial strength, water volume and dose into a syringe mark.
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Is Mounjaro better than Ozempic?
In the one head-to-head trial, SURPASS-2, tirzepatide (Mounjaro) at 5, 10 and 15 mg lowered HbA1c more than semaglutide 1 mg (Ozempic) over 40 weeks, by 0.15, 0.39 and 0.45 percentage points, and produced more weight loss. The trial was open label and funded by Eli Lilly, and it used the 1 mg Ozempic dose, not the 2 mg dose now on the label.
What is the difference between Ozempic and Mounjaro?
Ozempic contains semaglutide, a GLP-1 receptor agonist from Novo Nordisk, and tops out at 2 mg a week. Mounjaro contains tirzepatide, which activates GIP and GLP-1 receptors, comes from Eli Lilly and goes up to 15 mg a week. Both are labelled for type 2 diabetes and for lowering cardiovascular risk in adults with it.
Is Ozempic or Mounjaro approved for weight loss?
Neither label lists weight reduction as an indication. The weight-loss brands are Wegovy (semaglutide) and Zepbound (tirzepatide).
Can you take Ozempic and Mounjaro together?
The Zepbound and Wegovy labels both say coadministration with any other GLP-1 receptor agonist is not recommended, and Mounjaro and Ozempic work through the same receptor. Whether to switch from one to the other is a decision for a prescriber.
Sources (checked 6 November 2026)
- Ozempic prescribing information, Novo Nordisk, revised 5/2026. Checked 6 November 2026.
- Mounjaro prescribing information, Eli Lilly, revised 8/2026, DailyMed. Checked 6 November 2026.
- Frias et al, Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes (SURPASS-2), New England Journal of Medicine, 2021. Checked 6 November 2026.
Label figures are from the Ozempic label revised May 2026 and the Mounjaro label revised August 2026. Labels and trial records change; the leaflet in your box and your prescriber come first. Educational content, not medical advice.