Mounjaro vs Ozempic: which one should you choose?

Medically reviewed by Dr. Jaramillo, a doctor at Goodweigh. Last updated on 16 October 2026

Short answer from Dr. Jaramillo

Mounjaro or Ozempic: in a head-to-head comparison, Mounjaro resulted in greater weight loss than semaglutide, the active ingredient in Ozempic and Wegovy, in people with obesity who do not have diabetes. Ozempic is intended for diabetes, whilst Wegovy is the semaglutide-based medicine for weight management. The side effects are very similar, and your doctor will work with you to decide which medicine is right for you.

Dr. Jaramillo, doctor at Goodweigh

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Anyone looking to lose weight with medication will soon find themselves asking: Mounjaro or Ozempic? The short answer is that, in a direct comparison, Mounjaro resulted in greater weight loss, but this may not necessarily be the best choice for everyone. Below, you can read about what these medicines have in common, how they differ, and what to look out for when making your choice. We’ve also included Wegovy and the Wegovy tablet, as people searching for Ozempic often mean weight loss.

What is the difference between Mounjaro and Ozempic?

The main difference is the active ingredient: Mounjaro contains tirzepatide, whilst Ozempic contains semaglutide. Both are injected under the skin once a week.

Semaglutide mimics the hormone GLP-1. This causes your stomach to empty more slowly, so you feel less hungry. Tirzepatide mimics not only GLP-1 but also the hormone GIP, as described in a review article in Cardiovascular Diabetology. Whether this explains the difference in weight loss has not been demonstrated.

The second difference concerns the marketing authorisation. Ozempic is intended for adults with type 2 diabetes. For weight management, the same semaglutide is available under the name Wegovy, with its own patient information leaflet. Read more in Is Ozempic the same as Wegovy?. Mounjaro covers both indications under a single name: type 2 diabetes and weight management. So, if you’re comparing Mounjaro with semaglutide for weight loss, you’re actually comparing Mounjaro with Wegovy.

Which medicine leads to greater weight loss?

In people without diabetes, Mounjaro resulted in greater weight loss than semaglutide in a head-to-head comparison. In a direct comparison (SURMOUNT-5, New England Journal of Medicine), people taking tirzepatide lost an average of 20.2 per cent of their body weight after almost one and a half years. With semaglutide, the figure was 13.7 per cent. Their waist circumference also decreased more significantly. More people on tirzepatide lost a tenth, a fifth or even a quarter of their weight.

However, clinical studies have limitations: SURMOUNT-5 involved 751 participants with obesity but without diabetes, pushed to the highest tolerated doses, and was funded by the manufacturer (Eli Lilly). These findings do not automatically apply to patients with type 2 diabetes, lower dosing schedules, or standard Ozempic titration regimens. Weight-loss outcomes vary significantly from person to person.

Comparison of Mounjaro, Ozempic, Wegovy and the Wegovy tablet

The table compares the treatments side by side. The weight figures are taken from separate studies involving different participants and of different durations, so do not compare them with one another. Only SURMOUNT-5 directly compares Mounjaro with semaglutide in people without diabetes.

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What is Wegovy and what is the Wegovy tablet?

Wegovy is Ozempic for weight management: the same active ingredient, a separate brand name and a separate indication. In the STEP 8 study, people taking Wegovy lost an average of 15.8% of their body weight after 68 weeks. This figure comes from a different study to SURMOUNT-5. Please also read about the side effects of Wegovy.

The Wegovy tablet contains semaglutide. According to the European Medicines Agency (EMA), you take it once a day on an empty stomach, as an alternative to the injection. You can find out whether and when it is available on the Wegovy tablet page. You can read more about the tablet in Wegovy tablet: oral semaglutide. There is no direct comparison between the tablet and Mounjaro, so we do not provide any figures for this.

How do the dosage and regimen differ?

With all injections, you start with a low dose and build it up gradually so that your body gets used to the medicine. With Mounjaro, you start with 2.5 mg per week, followed by a higher dose after four weeks. The dose can then be increased in stages, up to a maximum of 15 mg.

With Wegovy, you start on a low dose and it takes around 16 weeks to reach the maintenance dose of 2.4 mg.

With Ozempic, the starting dose of 0.25 mg is not the maintenance dose, and the maximum dose is 2 mg.

With Goodweigh, you gradually build up the dose; with Wegovy and Mounjaro, this takes 16 to 20 weeks, and a doctor monitors your symptoms. That pace isn’t the same for everyone.

Which medicine causes the most side effects?

The side effects are very similar. According to the Farmacotherapeutisch Kompas, nausea, vomiting, diarrhoea and constipation are common with semaglutide and tirzepatide, affecting more than 1 in 10 users. In the SURMOUNT-5 trial, gastrointestinal symptoms were the most common in both groups, usually mild to moderate in severity and occurring mainly during dose escalation.

With Mounjaro, nausea, vomiting and diarrhoea tend to ease over time. Drink plenty of fluids during acute episodes of vomiting or diarrhoea to prevent dehydration. Contact your doctor immediately if you experience severe, persistent abdominal pain radiating to the back, as this can be a sign of acute pancreatitis. Use with extreme caution if you have a history of pancreatic conditions. Hair loss is documented in product leaflets following significant weight loss. Rare events such as NAION (non-arteritic anterior ischemic optic neuropathy) are noted in semaglutide literature; seek immediate medical attention if you experience sudden visual changes. You can read more about this under the side effects of tirzepatide.

What do you need to know about contraception and pregnancy?

If you could become pregnant, you should use contraception whilst taking any of these three medicines. If you are trying to conceive or are already pregnant, please discuss this with your doctor first.

Special note on Mounjaro: the contraceptive pill may be absorbed less effectively after a single dose, although the patient information leaflet states that this is not clinically relevant. Our doctors nevertheless advise using a condom for up to four weeks after each dose increase.

What does the difference cost, and can you switch?

We do not comment on the price here, as it varies depending on the period and the dose. For more information, see Weight-loss medication: price and effectiveness or the product page. If you wish to switch from Ozempic to Mounjaro, a doctor will assess this. There is no fixed conversion between the doses, so do not switch on your own initiative.

Would you like to see all the options, including those other than Mounjaro and semaglutide? Then take a look at this comparison of alternatives to Ozempic.

Which medicine is right for you?

That depends on your health, your goal, how well you tolerate the medication and what you’re able to take. If you have type 2 diabetes, could become pregnant, or have previously had pancreatitis, your doctor will take these factors into account. Greater weight loss in a trial does not mean that Mounjaro is necessarily better for you.

At Goodweigh, you complete an online intake. A doctor will review your details and discuss with you which medication is suitable. You can start your online intake whenever you’re ready.

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