Mounjaro (tirzepatide) and Ozempic (semaglutide) are both weekly injections approved for type 2 diabetes, but they work on different receptors. Mounjaro is a dual GIP/GLP-1 receptor agonist; Ozempic is a GLP-1 receptor agonist. In the only head-to-head trial — SURPASS-2 — Mounjaro produced greater A1C reduction (~2.3 percentage points at 15 mg) and weight loss (~11 kg) than Ozempic 1 mg (1.9 percentage points and ~6 kg). Ozempic has a formal cardiovascular risk reduction indication; Mounjaro’s outcome trial is pending.
Side-by-Side Comparison
| Feature | Mounjaro | Ozempic |
|---|---|---|
| Generic name | Tirzepatide | Semaglutide |
| Manufacturer | Eli Lilly | Novo Nordisk |
| Mechanism | GIP + GLP-1 dual agonist | GLP-1 single agonist |
| FDA indication | Type 2 diabetes | Type 2 diabetes; CV risk reduction in T2D + CVD |
| Dose range | 2.5 to 15 mg weekly | 0.25 to 2 mg weekly |
| Frequency | Weekly SC injection | Weekly SC injection |
| Titration | Monthly to 2.5, 5, 7.5, 10, 12.5, 15 mg | Monthly to 0.5, 1, 2 mg |
| A1C reduction (max dose) | ~2.3 percentage points | ~1.8–2.1 percentage points |
| Weight loss (T2D dose) | ~11–12% body weight | ~6–7% body weight |
| CV outcomes trial | SURPASS-CVOT (pending) | SUSTAIN-6 (26% MACE reduction) |
| Approval year | May 2022 | December 2017 |
| Pen type | Single-dose auto-injector | Multi-dose pen |
| List price/month | ~$1,070 | ~$970 |
| Boxed warning | Thyroid C-cell tumors | Thyroid C-cell tumors |
What Each One Is
Mounjaro (tirzepatide) is a once-weekly subcutaneous injection that activates two incretin receptors — GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1). It was FDA-approved in May 2022 for type 2 diabetes. The same molecule is also marketed as Zepbound for chronic weight management.
Ozempic (semaglutide) is a once-weekly subcutaneous injection that activates the GLP-1 receptor. It was FDA-approved in December 2017 for type 2 diabetes. The same molecule is also marketed as Wegovy (higher doses for obesity) and Rybelsus (oral tablet for type 2 diabetes). Read more on our semaglutide overview.
Head-to-Head Trial — SURPASS-2
The SURPASS-2 trial directly compared the two medications over 40 weeks in 1,879 adults with type 2 diabetes on metformin. Mean baseline A1C was 8.3 percent.
| Outcome | Tirzepatide 5 mg | Tirzepatide 10 mg | Tirzepatide 15 mg | Semaglutide 1 mg |
|---|---|---|---|---|
| A1C reduction | 2.01% | 2.24% | 2.30% | 1.86% |
| Weight loss | 7.6 kg | 9.3 kg | 11.2 kg | 5.7 kg |
| A1C below 7.0% | 82% | 86% | 86% | 79% |
| A1C below 5.7% | 27% | 40% | 46% | 19% |
SURPASS-2 used Ozempic 1 mg as the comparator — not the now-available 2 mg dose. At 2 mg, Ozempic A1C reduction and weight loss are slightly higher than at 1 mg but still typically lower than Mounjaro 15 mg.
Mechanism Differences
- Both stimulate glucose-dependent insulin secretion, slow gastric emptying, and suppress glucagon
- Mounjaro additionally activates GIP receptors, which may amplify insulin secretion, improve adipose tissue insulin sensitivity, and contribute to greater weight loss
- Some data suggest GIP activity helps offset GLP-1-induced GI side effects, though clinical trials show comparable GI rates
Cardiovascular Outcomes
Ozempic — The SUSTAIN-6 trial (3,297 patients with T2D and CVD or high CV risk) showed a 26 percent reduction in major adverse cardiovascular events. SELECT in 2023 added a 20 percent MACE reduction in obesity without diabetes (using semaglutide 2.4 mg, marketed as Wegovy). Ozempic carries a formal cardiovascular risk reduction indication.
Mounjaro — The SURPASS-CVOT outcome trial is ongoing, with primary results expected 2025-2026. Preliminary analyses suggest cardiovascular safety similar to GLP-1 RAs, but cardiovascular risk reduction is not yet a labeled indication.
When to Choose Mounjaro
- Goal of greater A1C reduction beyond what Ozempic can achieve
- Higher BMI patient where greater weight loss is desired alongside diabetes control
- Inadequate response to a maximally titrated GLP-1 receptor agonist
- Single-dose disposable pens preferred
When to Choose Ozempic
- Established cardiovascular disease where formal cardiovascular indication and outcome data matter
- Insurance covers Ozempic but not Mounjaro
- Longer real-world experience preferred
- Patient prefers a multi-dose pen with dose flexibility
Side Effects (Both)
- Nausea (most common) — usually peaks in first 2 to 4 weeks after each dose increase
- Vomiting, diarrhea, constipation
- Abdominal pain, dyspepsia
- Decreased appetite
- Fatigue
- Injection site reactions
- Gallbladder issues
- Pancreatitis (rare)
- Acute kidney injury (often dehydration-driven)
- Thyroid C-cell tumor boxed warning
Cost and Coverage
List prices are similar — about $1,070/month for Mounjaro and $970/month for Ozempic. Insurance coverage varies. Many type 2 diabetes patients are approved for either with prior authorization. Manufacturer savings cards can lower commercial copays substantially. Out-of-pocket cash costs run roughly $1,000 monthly for either drug.
Switching Between Them
No washout period is required. The typical approach is to discontinue the first drug and start the other at its lowest dose, titrating monthly. Mounjaro starts at 2.5 mg weekly. Ozempic starts at 0.25 mg weekly. Patients tolerating maximum doses of one may sometimes skip the lowest dose of the other under physician guidance, though caution is warranted to limit GI side effects.
Lifestyle Pairing
Both medications work best alongside diet and activity changes. Read more about diet for blood sugar and reversing prediabetes.
The Bottom Line
Mounjaro produces greater A1C reduction and weight loss than Ozempic in head-to-head data, owing to its dual GIP/GLP-1 mechanism. Ozempic has more mature cardiovascular outcome data and a formal CV risk reduction indication. Side effects are similar. Insurance coverage often dictates the choice in practice. Talk to your doctor about which medication fits your goals, your cardiovascular profile, and what your insurance covers. Both are first-line options for many patients with type 2 diabetes who need more than metformin.
