Ozempic vs Wegovy vs Mounjaro vs Zepbound
Two drugs wearing four names. The molecule decides how it works. The label decides what it is approved for, what dose it comes in, and what insurance will say.
The most useful thing to know is that this is a two-by-two grid. Ozempic and Wegovy are both semaglutide. Mounjaro and Zepbound are both tirzepatide. Within each pair, the diabetes brand and the weight brand are the same drug with a different label, dose range and price negotiation.
| Ozempic | Wegovy | Mounjaro | Zepbound | |
|---|---|---|---|---|
| Molecule | Semaglutide | Semaglutide | Tirzepatide | Tirzepatide |
| Mechanism | GLP-1 receptor agonist | GLP-1 and GIP receptor agonist | ||
| Maker | Novo Nordisk | Eli Lilly | ||
| Approved for | Type 2 diabetes, cardiovascular risk reduction, chronic kidney disease in diabetes | Chronic weight management, cardiovascular risk reduction, MASH | Type 2 diabetes | Chronic weight management, obstructive sleep apnoea |
| Doses | 0.25, 0.5, 1, 2 mg weekly | 0.25 to 2.4 mg weekly | 2.5 to 15 mg weekly | |
| Half-life | About 7 days | About 5 days | ||
| Pivotal weight result | About 15% over 68 weeks (STEP 1, 2.4 mg) | About 21% over 72 weeks (SURMOUNT-1, 15 mg) | ||
| Missed dose window | 5 days | Take if next dose is more than 48 hours away | 4 days | |
Semaglutide vs tirzepatide
Semaglutide acts on one receptor, GLP-1. Tirzepatide acts on that one and on GIP, a second gut peptide receptor. In the head-to-head SURMOUNT-5 trial, people on tirzepatide lost about 20 percent of body weight over 72 weeks against about 14 percent on semaglutide, with similar rates of gut side effects. That is the clearest comparison available and it favours tirzepatide for weight. For diabetes, both lower HbA1c substantially; tirzepatide by somewhat more in the SURPASS-2 trial.
Semaglutide has the longer cardiovascular outcomes record. The SELECT trial showed a 20 percent reduction in major cardiovascular events in people with heart disease and obesity, which is why Wegovy carries that indication. Tirzepatide's cardiovascular outcomes trial reported later and the labels have been catching up.
Ozempic vs Wegovy
Same molecule. Ozempic tops out at 2 mg and is labelled for diabetes. Wegovy goes to 2.4 mg and is labelled for weight, cardiovascular risk and, since 2025, MASH. The pens differ. Insurance treats them differently: a diabetes diagnosis usually unlocks Ozempic, while Wegovy often needs prior authorisation on BMI. Prescribing Ozempic for weight without diabetes is off-label, common, and sometimes the only way coverage works.
Mounjaro vs Zepbound
Same molecule, same doses, same pen. Mounjaro is the diabetes label, Zepbound the weight and sleep apnoea label. Zepbound is also sold as single-dose vials through LillyDirect at self-pay prices, which Mounjaro is not. The costs page has the numbers.
Which one
That is a conversation with a prescriber, and it mostly turns on what you are treating, what coverage you have, and how you tolerate the first weeks. What the log contributes is the second half of that: after a month on either, the side effect curve and the weight line say more than the trial averages do. Peptide AI has all four as compounds, with the label titration set up, on the free tier. Each has its own tracker page: Ozempic, Wegovy, Mounjaro, Zepbound.
Questions people ask
Is Wegovy the same as Ozempic?
Same molecule, semaglutide, from the same maker. Wegovy is labelled for weight management and goes up to 2.4 mg weekly. Ozempic is labelled for type 2 diabetes and goes up to 2 mg.
Is Zepbound the same as Mounjaro?
Same molecule, tirzepatide, same doses and pen, from the same maker. Zepbound is labelled for weight management and sleep apnoea, Mounjaro for type 2 diabetes.
Which is stronger, semaglutide or tirzepatide?
For weight loss, tirzepatide, in the head-to-head SURMOUNT-5 trial: about 20 percent versus about 14 percent over 72 weeks. Gut side effects were similar.
Can I switch from Ozempic to Mounjaro?
With a prescriber, yes. There is no dose conversion between the two drugs; tirzepatide usually starts at 2.5 or 5 mg. Our switching page covers how it normally goes.
Sources
- Ozempic prescribing information, Novo Nordisk
- Wegovy prescribing information, Novo Nordisk
- Mounjaro prescribing information, Eli Lilly
- Zepbound prescribing information, Eli Lilly
- Once-weekly semaglutide in adults with overweight or obesity (STEP 1), New England Journal of Medicine, 2021
- Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1), New England Journal of Medicine, 2022
- Tirzepatide as compared with semaglutide for the treatment of obesity (SURMOUNT-5), New England Journal of Medicine, 2025
