Key Takeaways
- Wegovy (semaglutide) targets GLP-1 receptors alone, whereas Mounjaro (tirzepatide) activates both GLP-1 and GIP receptors, achieving 20–22.5% average weight loss at 15mg in SURMOUNT-1.
- Never overlap Wegovy and Mounjaro: clinicians typically advise a 2-week gap (or 4 weeks if recovering from GI side effects) before starting Mounjaro.
- Because semaglutide and tirzepatide are distinct molecules, treatment restarts at Mounjaro’s 2.5mg introductory dose and steps up every 4 weeks.
If your progress on semaglutide (Wegovy) has plateaued or persistent side effects haven’t settled, you may wonder whether switching to tirzepatide (Mounjaro) makes clinical sense. With prescriber supervision, transitioning between weekly GLP-1 therapies is straightforward and safe (1–3).
Wegovy vs. Mounjaro: how the two weekly injections compare
| Feature | Wegovy (Semaglutide) | Mounjaro (Tirzepatide) |
|---|---|---|
| Active Ingredient | Semaglutide | Tirzepatide |
| Receptor Mechanism | Single GLP-1 receptor agonist | Dual GLP-1 + GIP receptor agonist (1) |
| Dosing Schedule | Once weekly | Once weekly |
| Strength Range | 0.25mg → 2.4mg (up to 7.2mg in select regions) | 2.5mg → 15mg across 6 dose steps |
| Clinical Trial Weight Loss | ~15–17% at 2.4mg (STEP-1); 19–21% at 7.2mg (STEP UP) (6) | 20–22.5% at 15mg over 72 weeks (SURMOUNT-1) (2,7) |
| Additional Licensed Benefits | 20% MACE reduction in established CVD + BMI ≥27 | Type 2 diabetes glycemic control |
Head-to-head trials published in the New England Journal of Medicine and JAMA Internal Medicine confirm dual GIP/GLP-1 therapy produces slightly greater average weight reduction than semaglutide, though individual responses vary (2,3).
The 5-step protocol for switching safely from Wegovy to Mounjaro
- Review your progress with a licensed clinician to confirm switching is preferable to adjusting your current Wegovy strength.
- Take your final Wegovy injection on your normal day — never overlap both medications simultaneously.
- Allow an appropriate washout interval: Typically at least 2 weeks after your final Wegovy pen (or 4 weeks if you experienced troublesome gastrointestinal side effects).
- Begin Mounjaro at the 2.5mg starting strength: Because semaglutide and tirzepatide are distinct molecules, doses do not cross-convert directly — starting at 2.5mg protects against severe nausea.
- Titrate gradually every 4+ weeks (5mg, 7.5mg, 10mg, 12.5mg, 15mg) until reaching a comfortable, effective maintenance strength.
During your first 4 weeks on 2.5mg tirzepatide, appetite suppression may temporarily feel lighter than on high-dose Wegovy — stay consistent with protein-rich meals while your dose builds back to steady therapeutic levels. Consult an Amble clinician to personalize your transition safely.
References
- Liu QK. Mechanisms of action and therapeutic applications of GLP-1 and dual GIP/GLP-1 receptor agonists. Front Endocrinol. 2024;15.
- Aronne LJ, Horn DB, le Roux CW, et al. Tirzepatide as Compared with Semaglutide for the Treatment of Obesity (SURMOUNT-5). N Engl J Med. 2025;393(1).
- Rodriguez PJ, et al. Semaglutide vs Tirzepatide for Weight Loss in Adults With Overweight or Obesity. JAMA Intern Med. 2024;184(9).
- Wharton S, et al. Once-weekly semaglutide 7.2mg in adults with obesity (STEP UP)00226-8/abstract). Lancet Diabetes Endocrinol. 2025.
- Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). N Engl J Med. 2022;387(3):205–216.
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