Compare weight-loss injections
Pick any two of Mounjaro, Wegovy, Ozempic and Saxenda to see them side by side: class, doses, pens, storage, NHS access and trial results. It shows the facts, not a verdict.
Updated 30 October 2026
| Mounjaro | Wegovy | |
|---|---|---|
| Active ingredient | tirzepatide | semaglutide |
| Drug class | Dual GIP + GLP-1 | GLP-1 |
| How often | Once a week | Once a week |
| Licensed in the UK for | Weight management (also type 2 diabetes) | Weight management |
| Pen | KwikPen | FlexTouch |
| Starting dose | 2.5 mg | 0.25 mg |
| Maintenance dose | 5, 10 or 15 mg | 2.4 mg (optional 7.2 mg) |
| Highest dose | 15 mg | 7.2 mg |
| Storage once in use | Up to 30 days below 30 °C | Up to 6 weeks below 30 °C |
| Average weight loss in trials | about 21% (SURMOUNT-1, 72 weeks (15 mg)) | about 15% (STEP-1, 68 weeks (2.4 mg)) |
| Trial figures are averages over the whole study, at the top dose. Real-world results vary. | ||
| NHS availability | On NHS weight-management pathways (criteria apply) | Via specialist NHS weight-management services |
Head to head
In SURMOUNT-5, the first head-to-head trial, average weight loss over 72 weeks was 20.2% with tirzepatide versus 13.7% with semaglutide. It was an open-label trial funded by the maker of tirzepatide. SURMOUNT-5 (NEJM).
Thinking of switching?
There’s no simple dose-for-dose swap between these; they’re different medicines. A switch means starting the new one at its lowest dose and titrating up again, under your prescriber. People’s experience of switching varies a lot, so the GLP-1 communities are worth a read for the lived side.
Facts from the UK SmPCs (Mounjaro, Wegovy) and the trials linked above.
This compares the facts; it doesn’t say which is right for you. That’s a decision for you and your prescriber.
Common questions
- Which weight-loss injection is best?
- There’s no single “best”. It depends on your health, what you’re prescribed and what you tolerate. This tool lays out the facts so you and your prescriber can talk it through. In the one head-to-head trial so far (SURMOUNT-5), tirzepatide averaged more weight loss than semaglutide, but averages don’t predict any individual’s result.
- Which of these are licensed for weight loss in the UK?
- Mounjaro, Wegovy and Saxenda are licensed for weight management. Ozempic is licensed for type 2 diabetes, not weight loss.
- Are they all weekly injections?
- Mounjaro, Wegovy and Ozempic are once-weekly. Saxenda is a daily injection.