Wegovy or Mounjaro? Which GLP-1 Treatment Should You Choose?

Wegovy or Mounjaro: how do they compare in effectiveness and cost?

Wegovy and Mounjaro can help treat obesity. The most suitable option depends on your weight loss goals, health, side effects and budget.

Both are indicated for adults with a BMI of 30 or above, or 27 or above with a weight-related health condition. They are used alongside dietary changes and physical activity.

How do they work?

Wegovy contains semaglutide, which acts on the GLP-1 receptor. Mounjaro contains tirzepatide, which acts on two receptors: GLP-1 and GIP. Both help reduce appetite and are injected once a week.

Both active ingredients are also used to treat type 2 diabetes: tirzepatide under the name Mounjaro, and semaglutide under the name Ozempic. Wegovy is the semaglutide treatment for weight management; the approved uses and doses of Wegovy and Ozempic differ.

Which treatment produces greater weight loss?

In the SURMOUNT-5 trial, which directly compared the treatments in adults with obesity without diabetes, average weight loss after 72 weeks was:

Treatment studiedAverage weight lossWegovy: maximum tolerated dose of 1.7 or 2.4 mg13.7%Mounjaro: maximum tolerated dose of 10 or 15 mg20.2%

For someone starting at 100 kg, these percentages would correspond to approximately 14 kg versus 20 kg. These are averages, not predictions for an individual patient. The results do not automatically apply to lower doses.

The trial was open-label: participants and doctors knew which treatment was being given.

🔴 Important: the SURMOUNT-5 trial was funded by Eli Lilly, the manufacturer of Mounjaro. This does not automatically make the results unreliable, but the funding is relevant when assessing the findings.

This comparison concerns Wegovy doses up to 2.4 mg. The newer 7.2 mg dose is now included in the European product information but was not investigated in this direct comparison.

How much do the treatments cost?

The following retail prices were taken from the Belgian medicines listing dated 5 October 2026. Each pen listed contains four weekly doses.

WegovyPrice for 4 weeksMounjaroPrice for 4 weeks0.25 mg€144.822.5 mg€179.780.5 mg€144.825 mg€241.161 mg€144.827.5 mg€333.231.7 mg€165.5710 mg€333.232.4 mg€189.48——

Doses shown on the same row are not equivalent. These are retail prices before any reimbursement. Prices for Mounjaro 12.5 and 15 mg are not included.

Wegovy 2.4 mg costs €143.75 less per four weeks than Mounjaro 10 mg. Four weeks is not a full calendar month: 52 weeks of treatment requires 13 pens.

Which treatment should you start with — and why?

There is no single best first choice for everyone.

Wegovy may be a reasonable first choice when affordability is a major consideration. At the prices listed, it costs less while still offering the possibility of substantial weight loss.

Mounjaro may be a reasonable first choice when greater weight loss is medically desirable and the higher cost is manageable. The direct comparison supports this consideration at the doses studied.

For people with established cardiovascular disease, the evidence for semaglutide may influence the decision. In the SELECT trial, involving people with overweight or obesity and established cardiovascular disease without diabetes, semaglutide reduced the combined risk of heart attack, stroke or cardiovascular death.

These are considerations, not a fixed prescribing sequence. Dr Didier Hebberecht also reviews your other medicines and medical history. Together with you, he chooses between Wegovy and Mounjaro, taking your health, preferences and financial circumstances into account.

Side effects, contraception and pregnancy

Both treatments can cause digestive symptoms such as nausea, vomiting, diarrhoea or constipation. These occur particularly during dose increases. The dose is therefore increased gradually, with follow-up throughout treatment.

Gallstones or inflammation of the gallbladder can also occur. Pancreatitis, an inflammation of the pancreas, is less common, but requires prompt medical assessment. Seek immediate medical advice if you develop severe, persistent abdominal pain, particularly if it spreads to your back or is accompanied by vomiting.

Mounjaro may make the oral contraceptive pill less reliable, particularly after starting treatment or increasing the dose. Discuss contraception with Dr Hebberecht; additional protection or a non-oral method may be appropriate. Vomiting or severe diarrhoea can also reduce the reliability of the pill.

Do not use Wegovy or Mounjaro during pregnancy. Discuss pregnancy plans beforehand: semaglutide should be stopped at least two months, and tirzepatide at least one month, before a planned pregnancy.

A personal note from Dr Didier Hebberecht

“After four years of experience with GLP-1 treatments, I have seen that results vary from patient to patient. In studies, patients taking Mounjaro lose more weight on average at the doses investigated. In my practice, the difference is smaller than I had expected. This is my personal clinical experience, rather than a direct scientific comparison.

When choosing a treatment, I am guided particularly by the patient’s financial circumstances, alongside the medical indication and tolerability. In my experience, Wegovy is certainly a good alternative to Mounjaro. Treatment also needs to be affordable.

Finally, we aim for the lowest dose that is sufficiently effective and well tolerated. We regularly review whether treatment is still needed and try to limit its duration where medically appropriate, while paying attention to maintaining the weight loss.”