The core difference
Semaglutide acts on one gut-hormone receptor (GLP-1). Tirzepatide acts on two (GLP-1 and GIP). The second signal appears to add to the effect on appetite and on how the body handles fat and sugar.
Head-to-head: SURMOUNT-5
In 2025, a trial compared the two directly in 751 adults with obesity and no diabetes, each at the highest tolerated dose, for 72 weeks:
| Outcome at 72 weeks | Semaglutide | Tirzepatide |
|---|---|---|
| Average weight loss | 13.7% | 20.2% |
| Waist reduction | About 13 cm | About 18 cm |
| Most common side effects | Nausea, constipation, diarrhoea | Nausea, constipation, diarrhoea |
Side-by-side
| Semaglutide | Tirzepatide | |
|---|---|---|
| Brands | Ozempic, Wegovy | Mounjaro, Zepbound |
| Receptors | GLP-1 | GLP-1 + GIP |
| Dosing | Weekly injection, stepped up gradually | Weekly injection, stepped up gradually |
| Proven heart benefit | Yes, in people with heart disease (SELECT) | Heart outcome data so far mainly in people with type 2 diabetes |
| Contraception | No known effect on the pill | Can reduce how well the pill works after starting and after each dose increase |
| Kenya status | Registered (several products) | Mounjaro under PPB review |
So which is "better"?
On average, tirzepatide produces more weight loss. That does not make it the right choice for everyone. The decision depends on:
- Your medical history, especially heart disease, diabetes, kidney function and digestive problems
- How much weight loss is clinically needed, and how quickly
- Contraception and pregnancy plans
- How you tolerate the starting doses
- Reliable, legitimate supply of the specific product
Whichever medicine is chosen, protein intake, strength training and sleep matter as much as the injection.
Talk it through with a doctor
Whether any of these medicines is right for you depends on your health, your history and your goals. The first phone consultation is free, and there is no obligation.
Book a free consultationSources
- Aronne et al. Tirzepatide as compared with semaglutide for the treatment of obesity (SURMOUNT-5). N Engl J Med 2025
- Wilding et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). N Engl J Med 2021
- Jastreboff et al. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1). N Engl J Med 2022
- Lincoff et al. Semaglutide and cardiovascular outcomes in obesity without diabetes (SELECT). N Engl J Med 2023