Comparison
Semaglutide vs Tirzepatide
Last updated Mon Jun 08 2026 00:00:00 GMT+0000 (Coordinated Universal Time)· 2 min read
Mechanism
- Semaglutide: pure GLP-1 receptor agonist.
- Tirzepatide: dual GIP + GLP-1 receptor agonist. The added GIP arm appears to contribute additional weight loss and possibly improved lipid effects, though the mechanism is still being worked out.
Weight-loss effect
| Semaglutide | Tirzepatide | |
|---|---|---|
| Phase-3 obesity trial | STEP-1 | SURMOUNT-1 |
| Weight loss (top dose) | ~15% | ~21% |
| % achieving ≥20% loss | ~32% | ~57% |
Tirzepatide produces meaningfully more weight loss head-to-head at typical maximum doses (SURPASS-2 in T2D, indirect comparisons in obesity).
Cardiovascular outcomes
- Semaglutide: SELECT trial (2023) showed 20% reduction in major cardiovascular events in obese non-diabetics. Substantial CVOT evidence base.
- Tirzepatide: SURMOUNT-MMO and other CV-outcome trials ongoing. No long-term hard-CV-endpoint evidence yet equivalent to semaglutide.
If a primary cardiovascular-protection indication is the reason for treatment, semaglutide has the larger evidence base right now.
Other endpoints
- Sleep apnea: tirzepatide showed ~50% AHI reduction in SURMOUNT-OSA (2024). Semaglutide also shows AHI improvement, smaller in magnitude.
- NASH/MASH: both improve liver enzymes and histology; trials ongoing.
- CKD: semaglutide FLOW trial (2024) showed 24% reduction in composite kidney-CV endpoint. Tirzepatide CKD-specific trials ongoing.
- Heart failure: tirzepatide SUMMIT trial (2024) improved HFpEF composite endpoint.
Side effects
Similar profiles (GI predominantly):
- Nausea, vomiting, diarrhoea common at start.
- Gallstones modestly elevated.
- Pancreatitis rare.
- Lean-mass loss with both — resistance training matters.
- Both carry thyroid-C-cell-tumour warning based on rodent data.
Cost and access
US list prices similar. Insurance coverage varies dramatically. Compounded versions of both are widely sold; quality and safety vary substantially.
Which to choose
- Maximum weight loss: tirzepatide.
- Best-evidenced cardiovascular outcomes today: semaglutide.
- Already on one and tolerating well: stay; the gain from switching is often smaller than the disruption.
- Cost-sensitive: depends on coverage; check both before deciding.