Semaglutide is a GLP-1 receptor agonist, while tirzepatide is a dual GLP-1 and GIP receptor agonist. Both reduce appetite, slow stomach emptying and improve blood sugar control. In the 72-week SURMOUNT-5 trial, tirzepatide produced greater average weight loss than semaglutide at the highest tolerated doses. The 2025 FDA labels also show that the medicines have different approved uses and warnings.
Which Is Better for Weight Loss?
Tirzepatide usually produces greater average weight loss, provided both medicines are medically appropriate and equally accessible.
In the 72-week SURMOUNT-5 head-to-head trial, adults with obesity or overweight and a weight-related health condition, but without diabetes, lost an average of:
- 20.2% of body weight with tirzepatide
- 13.7% of body weight with semaglutide
The trial compared the highest tolerated doses: tirzepatide 10 mg or 15 mg with semaglutide 1.7 mg or 2.4 mg. These results describe average outcomes. They do not mean that every person will lose more weight with tirzepatide.
Semaglutide vs. Tirzepatide: At a Glance
| Feature | Semaglutide | Tirzepatide |
|---|---|---|
| Main action | GLP-1 receptor agonist | Dual GLP-1 and GIP receptor agonist |
| Common U.S. brands | Wegovy for weight management; Ozempic for type 2 diabetes | Zepbound for weight management; Mounjaro for type 2 diabetes |
| Administration | Once-weekly injection for Wegovy and Ozempic | Once-weekly injection |
| Weight-management maintenance doses | Wegovy: 1.7 mg or 2.4 mg weekly | Zepbound: 5 mg, 10 mg or 15 mg weekly |
| Average weight loss in direct obesity trial | 13.7% at 72 weeks | 20.2% at 72 weeks |
| Additional FDA-labeled advantages | Wegovy reduces major cardiovascular events in certain adults with cardiovascular disease and overweight or obesity | Zepbound is also FDA-approved for moderate-to-severe obstructive sleep apnea in adults with obesity |
| Main limitation | Gastrointestinal side effects and semaglutide-specific warnings | Gastrointestinal side effects and tirzepatide-specific warnings |
The doses cannot be compared milligram for milligram. Semaglutide and tirzepatide are different molecules with different dose scales.
How Do the Medications Work Differently?
Semaglutide Is a GLP-1 Receptor Agonist
Semaglutide mimics glucagon-like peptide-1, or GLP-1. GLP-1 helps regulate appetite, food intake and blood glucose. Semaglutide also delays gastric emptying, which can help people feel full for longer.
Tirzepatide Activates GLP-1 and GIP Receptors
Tirzepatide activates the GLP-1 receptor and the glucose-dependent insulinotropic polypeptide, or GIP, receptor. This affects appetite, calorie intake, insulin release, glucagon levels and insulin sensitivity.
The combined action may help explain tirzepatide's greater average weight loss in the direct comparison trial. Individual responses still vary, and some people lose substantial weight with semaglutide.
What Is the Difference for Type 2 Diabetes?
Both medicines can lower blood glucose and A1C in adults with type 2 diabetes, but the comparison depends on the doses studied.
In the 40-week SURPASS-2 trial, tirzepatide at 5 mg, 10 mg and 15 mg was compared with semaglutide 1 mg in adults with type 2 diabetes. Tirzepatide produced greater reductions in A1C and body weight than semaglutide 1 mg. The estimated additional weight reduction with tirzepatide ranged from about 1.9 kg to 5.5 kg, depending on the tirzepatide dose.
The comparison needs context. Semaglutide 1 mg is a diabetes dose, while Wegovy for obesity has a maintenance dose of up to 2.4 mg weekly.
Which Medication Has Broader Advantages Beyond Weight Loss?
Semaglutide has a specific cardiovascular risk-reduction indication, while tirzepatide has a specific indication for obstructive sleep apnea in adults with obesity.
Semaglutide May Be Preferable for Some People With Cardiovascular Disease
Wegovy is FDA-approved to reduce the risk of cardiovascular death, heart attack and stroke in adults with established cardiovascular disease who have obesity or overweight. This indication may make semaglutide relevant for someone whose treatment goal includes cardiovascular risk reduction as well as weight loss.
Tirzepatide May Be Preferable for People With Obesity and Obstructive Sleep Apnea
Zepbound is FDA-approved, alongside diet and physical activity, to treat moderate-to-severe obstructive sleep apnea in adults with obesity.
Are the Side Effects Different?
The side-effect profiles overlap, and both medicines commonly cause gastrointestinal symptoms.
Common side effects include:
- Nausea
- Diarrhea
- Vomiting
- Constipation
- Abdominal pain
- Indigestion
- Reduced appetite
Side effects often become more noticeable after a dose increase. Both FDA labels warn about serious gastrointestinal reactions, dehydration-related kidney injury, gallbladder disease, pancreatitis, allergic reactions and low blood sugar when either medicine is used with insulin or certain diabetes medicines.
Both medicines also carry a boxed warning based on thyroid C-cell tumors observed in rodents. Neither should be used by people with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2.
Tolerability differs from person to person. Someone who cannot tolerate semaglutide may tolerate tirzepatide better, or the reverse. A healthcare professional may delay dose increases or choose a lower maintenance dose when gastrointestinal symptoms are significant.
Which One Should You Choose?
The choice depends on the treatment goal, medical history, tolerability and access.
Factors to discuss with a qualified prescriber include:
- Type 2 diabetes treatment goals
- Cardiovascular disease
- Obstructive sleep apnea
- Previous response to either medicine
- Nausea, vomiting or other gastrointestinal problems
- Insurance coverage and availability
- Other medicines, especially insulin or sulfonylureas
- Pregnancy plans and relevant medical history
Do not combine semaglutide with tirzepatide or use either medicine alongside another GLP-1 medicine unless specifically directed by a qualified prescriber.