💊 GLP-1 Drugs
Wegovy vs Mounjaro — Which Is Better for Weight Loss? (2026)
Direct comparison of Wegovy (semaglutide 2.4mg) and Mounjaro (tirzepatide) for weight loss — effectiveness, side effects, cost, and access. Updated January 2026.
Key Takeaways
- Mounjaro produces 20–22% weight loss vs Wegovy's 15–17% — a clinically meaningful difference
- At 1 year, Mounjaro 15mg produces on average 5–7 kg more weight loss than Wegovy 2.4mg
- Both cause weight regain when stopped — ongoing treatment is required
- SURMOUNT-5 trial (head-to-head) confirmed Mounjaro's superiority for weight loss
- Access and cost are broadly similar in UK and USA — both require prescription
The Direct Head-to-Head Trial: SURMOUNT-5
The SURMOUNT-5 trial (published 2025) directly compared tirzepatide (Mounjaro/Zepbound) against semaglutide 2.4mg (Wegovy) in people with obesity without diabetes. This was the definitive head-to-head comparison the medical community had been waiting for.
20.2%
Weight loss with tirzepatide 15mg (SURMOUNT-5)
13.7%
Weight loss with semaglutide 2.4mg (SURMOUNT-5)
47%
More people achieved ≥25% weight loss with tirzepatide
Complete Comparison
| Feature | Wegovy (Semaglutide 2.4mg) | Mounjaro (Tirzepatide) |
|---|---|---|
| Mechanism | GLP-1 agonist | Dual GLP-1 + GIP agonist |
| Average weight loss | 13.7–15% (STEP/SURMOUNT-5) | 20–22% (SURMOUNT) |
| ≥20% weight loss achievers | ~30% | ~55% |
| Max dose | 2.4mg weekly | 15mg weekly |
| CVD outcome trial | SELECT: 20% CVD reduction | SURMOUNT-MMO: ongoing |
| Diabetes approval | Ozempic (lower dose) | Mounjaro — both diabetes + obesity |
| UK NHS availability | Limited — specialist pathway | Limited — specialist pathway |
| Private monthly cost UK | £180–280 | £200–350 |
| Side effects | GI (nausea 44%) | GI (nausea 18–24%) — similar |
When to Choose Wegovy
- Existing cardiovascular disease: The SELECT trial provides robust CVD outcome data for semaglutide — particularly in people without diabetes. This data does not yet exist for tirzepatide (SURMOUNT-MMO ongoing).
- You want proven, longer-term data: Semaglutide has more long-term real-world safety data accumulated.
- Cost: Wegovy is often slightly less expensive than Mounjaro, particularly through private clinics.
When to Choose Mounjaro
- Maximum weight loss is the priority: If achieving ≥20% body weight loss is your goal, Mounjaro is significantly more likely to achieve this.
- You have Type 2 diabetes: Mounjaro produces greater HbA1c reduction (2.1% vs 1.5%) — more powerful for both conditions simultaneously.
- Previous inadequate response to Ozempic: Some patients who had limited results with semaglutide respond well to tirzepatide.
Frequently Asked Questions
Can you switch from Wegovy to Mounjaro?▼
Yes — switching is possible and sometimes recommended when Wegovy produces insufficient weight loss. When switching, typically start Mounjaro at a low dose (2.5mg or 5mg) rather than an equivalent dose to allow re-adaptation. Discuss timing with your prescriber — usually switch after a brief washout or at the next injection day.
Is there a trial comparing Wegovy and Mounjaro directly?▼
Yes — SURMOUNT-5 (2025) is the definitive head-to-head trial. Tirzepatide 15mg produced 20.2% weight loss vs semaglutide 2.4mg at 13.7% over 72 weeks. Approximately 47% of tirzepatide users achieved ≥25% weight loss vs 29% with semaglutide. Both were superior to placebo, but tirzepatide was clearly superior for weight loss.
Which drug is better for diabetes — Wegovy or Mounjaro?▼
For Type 2 diabetes: Mounjaro (tirzepatide) produces greater HbA1c reduction (2.1–2.3% vs 1.5–1.8% for semaglutide) and greater weight loss. For people with T2D + established cardiovascular disease where CVD outcomes are the priority: Ozempic (semaglutide 2mg) has the most robust CVD outcome trial data. Both are excellent choices — discuss with your diabetes physician.
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Mounjaro vs Ozempic
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Wegovy Complete Guide
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All GLP-1 Drugs Guide
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⚕️ Medical Disclaimer: This article is for informational purposes only. Always consult a qualified healthcare professional before starting or changing any medication or treatment.
Dr
Dr. Priya Sharma, MD
WellCalc Medical Contributor
All articles reviewed by qualified healthcare professionals following NHS, AHA, and WHO guidelines.