Tirzepatide vs. Semaglutide: Head-to-Head Comparison of GLP-1 Medications
How does tirzepatide (Mounjaro/Zepbound) stack up against semaglutide (Ozempic/Wegovy)? We compare efficacy, side effects, cost, and clinical trial data.
The two most talked-about weight loss and diabetes medications today are tirzepatide and semaglutide. While both belong to the incretin-based therapy class, they have important differences that may influence which is right for you.
Key Differences at a Glance
| Feature | Tirzepatide | Semaglutide |
|---|---|---|
| Mechanism | Dual GIP/GLP-1 agonist | GLP-1 agonist only |
| Brand Names | Mounjaro, Zepbound | Ozempic, Wegovy, Rybelsus |
| Administration | Weekly injection | Weekly injection (or daily oral) |
| Max Dose | 15 mg | 2.4 mg (Wegovy) |
| Avg Weight Loss | 20-25% | 15-17% |
| HbA1c Reduction | Up to 2.4% | Up to 1.8% |
SURPASS-2: The Direct Comparison
The SURPASS-2 trial directly compared tirzepatide to semaglutide 1 mg in patients with type 2 diabetes over 40 weeks. Results showed:
- Tirzepatide 5 mg: -2.01% HbA1c reduction, -7.6 kg weight loss
- Tirzepatide 10 mg: -2.24% HbA1c reduction, -9.3 kg weight loss
- Tirzepatide 15 mg: -2.30% HbA1c reduction, -11.2 kg weight loss
- Semaglutide 1 mg: -1.86% HbA1c reduction, -5.7 kg weight loss
All three tirzepatide doses showed statistically superior HbA1c reduction compared to semaglutide. For weight loss, the 10 mg and 15 mg doses were significantly better.
Weight Loss Comparison
In dedicated weight loss trials:
Tirzepatide (SURMOUNT-1): Participants lost an average of 22.5% of body weight at the highest dose (15 mg) over 72 weeks.
Semaglutide (STEP 1): Participants lost an average of 14.9% of body weight at 2.4 mg over 68 weeks.
This represents roughly 50% more weight loss with tirzepatide.
Side Effect Profiles
Both medications share similar gastrointestinal side effects, which are the most commonly reported:
- Nausea
- Diarrhea
- Vomiting
- Constipation
- Abdominal pain
The severity and frequency of these side effects are comparable between the two medications, though individual experiences vary significantly.
Cost Comparison
Without insurance, both medications carry a significant price tag:
- Tirzepatide (Mounjaro/Zepbound): ~$1,000-$1,200/month
- Semaglutide (Ozempic/Wegovy): ~$900-$1,350/month
Insurance coverage varies significantly and can reduce costs substantially for both medications.
The Bottom Line
Tirzepatide appears to offer superior efficacy for both blood sugar control and weight loss compared to semaglutide, likely due to its dual-action mechanism. However, both are effective medications, and the best choice depends on individual factors including insurance coverage, personal health goals, and provider recommendations.