Tirzepatide vs Semaglutide: Which GLP-1 Works Better for Weight Loss?
- Weight loss: Tirzepatide produces ~20% body weight loss vs ~14% for semaglutide in trials
- Mechanism: Tirzepatide targets two receptors (GIP + GLP-1); semaglutide targets one (GLP-1)
- Side effects: Similar for both medications
- Track record: Semaglutide has longer safety data and proven heart benefits
- Cost: Similar ($1,000-1,100/month brand, $200-600 compounded)
The quick answer
Tirzepatide (Mounjaro, Zepbound) produces more weight loss than semaglutide (Ozempic, Wegovy). In head-to-head trials, patients on tirzepatide lost 20.2% of their body weight compared to 13.7% on semaglutide.
That’s a real difference. For someone weighing 220 pounds, tirzepatide means losing about 44 pounds versus 30 pounds on semaglutide.
But semaglutide has been around longer, with more safety data and proven benefits for heart disease. Tirzepatide may catch up on the cardiovascular data, but it’s not there yet.
Head-to-head trial results
The SURMOUNT-5 trial compared tirzepatide and semaglutide directly in adults with obesity. This is the clearest comparison we have.
Results at 72 weeks
| Outcome | Tirzepatide (15mg) | Semaglutide (2.4mg) |
|---|---|---|
| Average weight loss | 20.2% Winner | 13.7% |
| Weight lost (220 lb person) | 44 lbs | 30 lbs |
| Patients losing 10%+ | 85% | 73% |
| Patients losing 20%+ | 57% | 28% |
Tirzepatide had roughly double the number of patients reaching 20% weight loss. That’s a meaningful difference for people with a lot to lose.
Real-world data backs this up. A 2026 retrospective study of US patients found tirzepatide produced 11.2% weight loss at 6 months versus 8.8% for semaglutide. The effect holds outside clinical trials.
How they work differently
Semaglutide (Ozempic, Wegovy)
- → Mimics GLP-1, a gut hormone that signals fullness
- → Slows stomach emptying
- → Reduces appetite
- → One mechanism of action
Tirzepatide (Mounjaro, Zepbound)
- → Mimics both GLP-1 and GIP
- → Same stomach-slowing and appetite effects
- → GIP may improve fat and blood sugar handling
- → Dual mechanism of action
The dual mechanism is likely why tirzepatide works better. Targeting two receptors instead of one produces stronger effects.
Weight loss comparison by timepoint
| Timepoint | Tirzepatide | Semaglutide |
|---|---|---|
| 3 months | 7-9% | 5-7% |
| 6 months | 12-15% | 8-11% |
| 12 months | 18-22% | 13-15% |
For a 200 lb person, that’s roughly 36-44 lbs lost on tirzepatide at 12 months versus 26-30 lbs on semaglutide.
Side effects comparison
Both medications cause similar gastrointestinal side effects, especially during the first few months:
| Side Effect | Tirzepatide | Semaglutide |
|---|---|---|
| Nausea | 20-30% | 20-30% |
| Diarrhea | 15-20% | 15-20% |
| Constipation | 10-15% | 10-15% |
| Vomiting | 10-15% | 10-15% |
| Injection site reaction | 5% | 5% |
The SURPASS-2 trial found slightly lower nausea rates with tirzepatide at equivalent doses, but the difference was small enough that it shouldn’t drive your decision.
Serious side effects are similar and rare for both: pancreatitis, gallbladder problems, and thyroid tumors (boxed warning based on animal studies).
Cost comparison
| Option | Tirzepatide | Semaglutide |
|---|---|---|
| Brand (without insurance) | $1,000-1,100/mo | $900-1,400/mo |
| Brand (with insurance) | $25-500/mo | $25-500/mo |
| Compounded | $300-600/mo | $200-500/mo |
Compounded tirzepatide typically costs $50-150 more per month than compounded semaglutide because the compound is newer and less widely available.
Which should you choose?
Choose tirzepatide if:
- → Maximum weight loss is your priority
- → You have a lot to lose (BMI 35+)
- → Semaglutide hasn’t worked well for you
- → You don’t have existing heart disease concerns
Choose semaglutide if:
- → You want the medication with the longest track record
- → You have heart disease or high cardiovascular risk
- → Cost is a concern (compounded is cheaper)
- → You’re already doing well on it
The honest answer: If weight loss is your main goal and cost isn’t an issue, tirzepatide produces better results. If you’re more cautious about newer medications or have heart health concerns, semaglutide’s longer track record is reassuring.
Some people start with semaglutide and switch to tirzepatide if they plateau. That’s a reasonable approach.
Frequently asked questions
The bottom line
Tirzepatide beats semaglutide for weight loss. The clinical data is clear on that. But semaglutide isn’t far behind, costs a bit less, and has more long-term safety data. Either one can produce significant results. The best choice depends on your goals, health history, and what your insurance covers.
References
- Aronne LJ, et al. Tirzepatide Once Weekly for the Treatment of Obesity in People With Type 2 Diabetes (SURMOUNT-5). New England Journal of Medicine. 2024.
- Rodriguez PJ, et al. Comparative effectiveness of tirzepatide and semaglutide for obesity management. Journal of Endocrinological Investigation. 2026.
- Frías JP, et al. Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes (SURPASS-2). New England Journal of Medicine. 2021.
- Eli Lilly. Mounjaro Prescribing Information. 2024.
- Novo Nordisk. Ozempic Prescribing Information. 2024.