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Semaglutide (Wegovy/Ozempic) and Tirzepatide (Mounjaro/Zepbound) are the two most prescribed incretin-based weight loss medications. Semaglutide is a pure GLP-1 receptor agonist, while Tirzepatide is a dual GIP/GLP-1 receptor agonist — meaning it activates an additional metabolic pathway.
Clinical trials have directly and indirectly compared these medications, with Tirzepatide generally showing greater average weight loss. However, the choice involves more than efficacy numbers — cost, availability, side effect profiles, and insurance coverage all factor into the equation.
| Dimension | Semaglutide | Tirzepatide |
|---|---|---|
| Drug Class | GLP-1 receptor agonist | Dual GIP/GLP-1 receptor agonist |
| Mechanism | Activates GLP-1 receptors (appetite, gastric emptying, insulin) | Activates both GIP and GLP-1 receptors (enhanced metabolic effect) |
| FDA Status | Approved (Wegovy for weight, Ozempic for T2D) | Approved (Zepbound for weight, Mounjaro for T2D) |
| Average Weight Loss | ~15% body weight (STEP trials, 2.4mg dose) | ~22.5% body weight (SURMOUNT trials, 15mg dose) |
| Dosing Frequency | Once weekly subcutaneous injection | Once weekly subcutaneous injection |
| Key Advantage | Longer track record, more post-market safety data | Greater average weight loss, dual mechanism |
| Nausea Rate | ~20% in clinical trials | ~15-18% in clinical trials |
| Cost (US) | ~$1,300-1,400/month (list price) | ~$1,000-1,100/month (list price) |
Semaglutide is a GLP-1 receptor agonist with 94% sequence homology to human glucagon-like peptide-1. Used for weight management (Wegovy) and type 2 diabetes (Ozempic). Demonstrates significant effects on appetite regulation and glucose control.
Tirzepatide is a dual GIP/GLP-1 receptor agonist for weight management and type 2 diabetes. Marketed as Mounjaro (diabetes) and Zepbound (weight management). Outperforms semaglutide in head-to-head trials for both glucose control and weight loss.
Semaglutide and Tirzepatide are not typically combined. Both are incretin mimetics with overlapping GLP-1 receptor activation, so stacking would increase GI side effects without clear additional benefit. Patients are generally prescribed one or the other based on efficacy goals, insurance coverage, and tolerability.
Tirzepatide has shown greater average weight loss in clinical trials. The SURMOUNT-1 trial reported up to 22.5% body weight reduction at the highest dose (15mg), compared to approximately 15% with Semaglutide 2.4mg in the STEP trials. The SURPASS trials also showed Tirzepatide outperforming Semaglutide 1mg for A1C reduction in diabetes.
Both medications share similar GI side effects (nausea, vomiting, diarrhea, constipation), which are most common during dose escalation. Clinical trial data suggests Tirzepatide may have slightly lower nausea rates than Semaglutide, though head-to-head comparisons are limited. Both generally improve in tolerability after the initial titration period.
Yes, both are FDA approved. Semaglutide is approved as Ozempic (for type 2 diabetes) and Wegovy (for chronic weight management). Tirzepatide is approved as Mounjaro (for type 2 diabetes) and Zepbound (for chronic weight management).