Ozempic vs Mounjaro: Weight Loss, Cost & Side Effects
A data-driven comparison of the two most popular GLP-1 weight loss medications. Both work — but they differ significantly in mechanism, efficacy, dosing, and cost.
Contents
Ozempic vs Mounjaro: Quick Comparison
| Factor | Ozempic (Semaglutide) | Mounjaro (Tirzepatide) |
|---|---|---|
| Manufacturer | Novo Nordisk | Eli Lilly |
| Mechanism | GLP-1 receptor agonist | Dual GIP + GLP-1 agonist |
| FDA-approved for | Type 2 diabetes | Type 2 diabetes + obesity |
| Weight loss version | Wegovy (2.4 mg) | Zepbound (up to 15 mg) |
| Max weight loss (trials) | ~14.9% (68 wks) | ~22.5% (72 wks) |
| Injection frequency | Once weekly | Once weekly |
| Dose range | 0.25 – 2.4 mg | 2.5 – 15 mg |
| Time to max dose | 16–20 weeks | 20–28 weeks |
| Key trial program | STEP (1-5) | SURMOUNT (1-4) |
| List price (monthly) | ~$935 (Ozempic) | ~$1,023 (Mounjaro) |
| With insurance/coupon | $0–$300 | $0–$550 |
| Available since | 2017 (diabetes), 2021 (obesity) | 2022 (diabetes), 2023 (obesity) |
Weight Loss: Clinical Trial Results
The most reliable comparison comes from the SURMOUNT-2 trial, which directly compared tirzepatide against semaglutide. But we can also compare across the STEP and SURMOUNT programs.
| Medication | Dose | Avg. Weight Loss | % Losing ≥10% | % Losing ≥20% | Duration |
|---|---|---|---|---|---|
| Ozempic | 1.0 mg | ~8% | ~35% | ~8% | 52 wks |
| Wegovy | 2.4 mg | ~14.9% | ~69% | ~32% | 68 wks |
| Mounjaro | 5 mg | ~15.0% | ~67% | ~32% | 72 wks |
| Mounjaro | 10 mg | ~19.5% | ~82% | ~46% | 72 wks |
| Mounjaro | 15 mg | ~22.5% | ~87% | ~57% | 72 wks |
| Placebo | — | ~2.4–3.1% | ~10% | ~2% | 68-72 wks |
Key finding: Mounjaro's lowest dose (5 mg) produces roughly the same weight loss as Wegovy's maximum dose (2.4 mg). At higher doses, Mounjaro's weight loss advantage widens to 5-8 percentage points.
How They Work Differently
Ozempic (semaglutide) mimics a single gut hormone — GLP-1 — which slows gastric emptying, reduces appetite, and increases insulin secretion. It's a targeted, single-pathway approach.
Mounjaro (tirzepatide) mimics two gut hormones simultaneously — GLP-1 and GIP. The addition of GIP receptor activation provides additional metabolic benefits:
- Enhanced fat metabolism beyond what GLP-1 alone achieves
- Improved insulin sensitivity through a complementary pathway
- Potentially greater energy expenditure (still being studied)
- Additive appetite suppression from two independent signaling pathways
This dual mechanism is the primary reason Mounjaro produces greater weight loss in clinical trials. It's not simply a higher dose of the same approach — it's a fundamentally broader mechanism.
Dosing Schedule Comparison
| Week | Ozempic/Wegovy | Mounjaro/Zepbound |
|---|---|---|
| 1–4 | 0.25 mg (initiation) | 2.5 mg (initiation) |
| 5–8 | 0.5 mg | 5.0 mg |
| 9–12 | 1.0 mg | 7.5 mg (optional) |
| 13–16 | 1.7 mg | 10.0 mg |
| 17–20 | 2.4 mg (max) | 12.5 mg (optional) |
| 21+ | — | 15.0 mg (max) |
Mounjaro takes slightly longer to reach maximum dose (20-28 weeks vs 16-20 weeks) because it has more dose steps. Both medications require gradual escalation to minimize nausea and other GI side effects.
Side Effects: How They Compare
| Side Effect | Ozempic/Wegovy | Mounjaro |
|---|---|---|
| Nausea | 44% | 31% |
| Diarrhea | 30% | 23% |
| Vomiting | 24% | 12% |
| Constipation | 24% | 17% |
| Abdominal pain | 20% | 14% |
| Injection site reaction | 3.2% | 5% |
| Discontinuation due to side effects | 7% | 6.3% |
Mounjaro appears to have lower rates of nausea and vomiting in trials, though direct comparison is limited because the trials used different populations. Both medications' GI side effects are most pronounced during dose escalation and typically improve after 4-6 weeks at a stable dose.
Cost Comparison (2026)
| Factor | Ozempic | Wegovy | Mounjaro | Zepbound |
|---|---|---|---|---|
| List price/month | ~$935 | ~$1,349 | ~$1,023 | ~$1,060 |
| With commercial insurance | $25–$150 | $0–$300 | $25–$150 | $0–$550 |
| Manufacturer savings | Yes (Novo Nordisk) | Yes (Novo Nordisk) | Yes (Eli Lilly) | Yes (Eli Lilly) |
| Compounded available? | Limited (2026) | Limited | Yes | Yes |
| Medicare Part D | Yes (diabetes) | Varies | Yes (diabetes) | Varies |
Actual out-of-pocket cost depends heavily on your insurance plan. Both manufacturers offer savings cards that can reduce copays to $0-$25/month for commercially insured patients. Without insurance, compounded versions may be available at lower cost but quality and regulation vary.
Which Medication Is Right for You?
This is a medical decision that should be made with your prescribing physician. The comparison below highlights general factors, not personalized medical advice.
Mounjaro/Zepbound may be preferred if:
- Maximum weight loss is the primary goal (22.5% vs 14.9%)
- You have type 2 diabetes (dual mechanism offers better glucose control)
- You've plateaued on semaglutide and want to try a different mechanism
Ozempic/Wegovy may be preferred if:
- Longer safety track record matters to you (on market since 2017 vs 2022)
- More real-world data and clinical experience is available
- Cardiovascular risk reduction is important (Wegovy has CV outcome data; Mounjaro's is pending)
- Your insurance covers one but not the other
Project Your Weight Loss on Each Medication
Use our calculators to see personalized projections based on your starting weight, dose, and treatment duration.
Ozempic Calculator Mounjaro Calculator Compare All 3Frequently Asked Questions
Can you switch from Ozempic to Mounjaro?
Yes, with your doctor's guidance. The typical approach is to stop Ozempic and start Mounjaro at the lowest dose (2.5 mg) regardless of your previous Ozempic dose, then escalate normally. Some doctors may start at a slightly higher Mounjaro dose if you've been on high-dose semaglutide, but this is an individual clinical decision.
Is Mounjaro always better than Ozempic for weight loss?
On average, yes — Mounjaro produces greater weight loss at comparable treatment durations. However, individual responses vary significantly. Some people respond exceptionally well to semaglutide and may not need tirzepatide. The "best" medication is the one that produces good results with tolerable side effects for you specifically.
Do you regain weight after stopping either medication?
Studies show significant weight regain after discontinuation of both medications. The STEP 1 extension trial found participants regained approximately two-thirds of lost weight within one year of stopping semaglutide. Long-term data for tirzepatide discontinuation is still being collected, but the pattern is expected to be similar. This is why many physicians recommend ongoing treatment.
Can you take Ozempic and Mounjaro together?
No. Both medications activate GLP-1 receptors, so combining them would increase the risk of severe side effects (particularly GI effects) without a proportional increase in benefit. They should not be used simultaneously.
Sources & References
- Wilding JPH, et al. "Once-weekly semaglutide in adults with overweight or obesity." N Engl J Med. 2021;384(11):989-1002. (STEP 1)
- Jastreboff AM, et al. "Tirzepatide once weekly for the treatment of obesity." N Engl J Med. 2022;387(3):205-216. (SURMOUNT-1)
- Garvey WT, et al. "Tirzepatide once weekly for the treatment of obesity in people with type 2 diabetes." Lancet. 2023;402(10402):613-626. (SURMOUNT-2)
- Rubino D, et al. "Effect of continued weekly subcutaneous semaglutide vs placebo on weight loss maintenance." JAMA. 2021;325(14):1414-1425. (STEP 4)
- Novo Nordisk. "Ozempic (semaglutide) prescribing information." FDA, 2024.
- Eli Lilly. "Mounjaro (tirzepatide) prescribing information." FDA, 2024.