Semaglutide vs Tirzepatide: Which GLP-1 Is Better for Weight Loss?
Semaglutide (Wegovy/Ozempic) and tirzepatide (Zepbound/Mounjaro) are the two most popular GLP-1 medications for weight loss. Both are injectable, both work remarkably well — but they have important differences in efficacy, cost, side effects, and availability.
Here's a complete, evidence-based comparison to help you understand the differences.
Quick Comparison: Semaglutide vs Tirzepatide
| Feature | Semaglutide | Tirzepatide |
|---|---|---|
| Brand Names | Wegovy, Ozempic, Rybelsus | Zepbound, Mounjaro |
| Mechanism | GLP-1 receptor agonist | Dual GIP + GLP-1 agonist |
| Average Weight Loss | ~15% of body weight | ~21% of body weight |
| Injection Frequency | Once weekly | Once weekly |
| FDA-Approved for Weight Loss | Yes (Wegovy) | Yes (Zepbound) |
| Compounded Available | Yes (widely) | Limited |
| Starting Price (Compounded) | $49/month | $249/month |
| Starting Price (Brand) | ~$1,349/month | ~$1,059/month |
| Oral Option | Yes (Rybelsus) | No (in trials) |
| Manufacturer | Novo Nordisk | Eli Lilly |
Weight Loss Results: Head-to-Head
The biggest difference is in weight loss efficacy. Tirzepatide consistently outperforms semaglutide in clinical trials:
Semaglutide Clinical Trial Results
- STEP 1: 14.9% weight loss (2.4mg dose, 68 weeks, n=1,961)
- STEP 2: 9.6% weight loss in patients with type 2 diabetes
- STEP 3: 16.0% weight loss with intensive behavioral therapy
- STEP 5: 15.2% weight loss maintained over 2 years
Tirzepatide Clinical Trial Results
- SURMOUNT-1: 20.9% weight loss (15mg dose, 72 weeks, n=2,539)
- SURMOUNT-2: 14.7% weight loss in patients with type 2 diabetes
- SURMOUNT-3: 26.6% weight loss with intensive lifestyle intervention
- SURMOUNT-4: Patients who switched to placebo regained weight, confirming continued use is needed
Winner: Tirzepatide — approximately 40% more weight loss than semaglutide on average.
How Do They Work Differently?
Semaglutide mimics GLP-1, a hormone that:
- Slows stomach emptying (you feel full longer)
- Reduces appetite signals in the brain
- Improves insulin sensitivity
Tirzepatide mimics both GLP-1 and GIP (glucose-dependent insulinotropic polypeptide), which:
- Does everything semaglutide does, plus...
- Enhances fat metabolism through GIP receptor activation
- May improve energy expenditure
- Shows additional benefits for fatty liver disease
The dual mechanism is likely why tirzepatide produces greater weight loss.
Side Effects Comparison
Both medications have similar gastrointestinal side effects, but there are some differences:
| Side Effect | Semaglutide | Tirzepatide |
|---|---|---|
| Nausea | 44% | 31% |
| Diarrhea | 30% | 23% |
| Vomiting | 24% | 12% |
| Constipation | 24% | 11% |
| Injection site reactions | 3.2% | 3.2% |
Winner: Tirzepatide — lower rates of most GI side effects despite greater weight loss.
Cost Comparison
Price is where semaglutide has a clear advantage:
- Cheapest semaglutide: $49/month (compounded, Hims & Hers)
- Cheapest tirzepatide: $249/month (compounded)
- Brand Wegovy: ~$1,349/month
- Brand Zepbound: ~$1,059/month
Compounded semaglutide is widely available and very affordable. Compounded tirzepatide is harder to find and more expensive.
Winner: Semaglutide — significantly cheaper, especially compounded versions.
Compare all prices on our GLP-1 comparison page.
Which One Should You Choose?
Consider semaglutide if:
- Budget is a primary concern
- You want the most affordable entry point ($49/month)
- You prefer an oral option (Rybelsus)
- Your insurance covers Wegovy but not Zepbound
- 15% weight loss would meet your goals
Consider tirzepatide if:
- Maximum weight loss is your priority
- You haven't responded well to semaglutide
- You have type 2 diabetes (dual GIP/GLP-1 benefits)
- Budget allows for the higher cost
- Your insurance covers Zepbound or Mounjaro
Important: This is not medical advice. The choice between semaglutide and tirzepatide should be made with your healthcare provider based on your individual health profile, goals, and medical history.
What About the Next Generation?
Several new GLP-1 medications are in clinical trials:
- Retatrutide (Eli Lilly): Triple agonist (GLP-1 + GIP + glucagon). Phase 3 trials showing ~24% weight loss.
- Survodutide (Boehringer Ingelheim): Dual glucagon/GLP-1 agonist with promising liver benefits.
- Oral semaglutide (higher dose): Novo Nordisk testing higher doses for weight loss without injections.
- Amycretin (Novo Nordisk): GLP-1/amylin dual agonist showing 13% weight loss in just 12 weeks.
These next-generation medications could surpass both semaglutide and tirzepatide within 2–3 years.
Medical Disclaimer
This article is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare provider before starting, stopping, or changing any medication. Individual results may vary. Reviewed by Christopher Thompson, MD.
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