Is Wegovy as effective as Mounjaro for weight loss?

The common misconception: that these two medicines work in roughly the same way

A lot of people assume Wegovy and Mounjaro are broadly interchangeable, two weekly injections, both cutting appetite, both producing significant weight loss. The reality is more interesting. Wegovy (semaglutide) activates a single hormone receptor, GLP-1, which slows gastric emptying and reduces appetite. Mounjaro (tirzepatide) activates two receptors (GLP-1 and GIP) making it the only dual-agonist weight-loss medicine licensed in the UK. That second pathway appears to add meaningful potency.

This isn't a minor pharmacological detail. In the SURMOUNT-5 trial, published in the New England Journal of Medicine in 2025, adults with obesity who took tirzepatide lost significantly more weight on average than those who took semaglutide 2.4mg over 72 weeks. NICE's appraisal of tirzepatide (TA1026) acknowledges indirect comparisons that favour tirzepatide over semaglutide. So the idea that they're equivalent is the misconception this page is here to correct, and if you want to explore whether Wegovy is genuinely as effective as Mounjaro, that question turns out to be more dose-dependent than most people expect.

There is one important caveat. A newer, higher-dose Wegovy pen (7.2mg weekly) was approved by the MHRA in early 2026, with trial data showing around 20.7% average weight loss over 72 weeks. That narrows the gap with Mounjaro 15mg considerably. The comparison is therefore dose-dependent, and it keeps moving.

What the numbers look like side by side

The table below pulls together the headline figures from the main phase-3 trials. Each number refers to average percentage body-weight reduction versus placebo, in adults without type 2 diabetes, over a similar timeframe. They are not directly comparable because the trials used different populations, designs and follow-up periods, but they give a useful order of magnitude.

Sources: STEP 1, NEJM; SURMOUNT-1, NEJM; MHRA approval announcement, April 2026. The SURMOUNT-5 head-to-head comparison (2025) confirmed tirzepatide produced greater average loss than semaglutide 2.4mg when given to matched populations.

What the table can't show: individual variation is substantial. Some people respond exceptionally well to semaglutide and less so to tirzepatide. Genetics, gut motility, baseline metabolic health and tolerability all play a part. A trial average is a population figure, not a personal prediction.

You can read more about how the two medicines compare on the Wegovy vs Mounjaro overview, which covers mechanism, eligibility and cost context in one place.

Eligibility, cost and the practical question of which you can actually access

Effectiveness on paper and effectiveness in practice are different things. Mounjaro may produce higher average results, but Wegovy has been available for longer, clinicians have more prescribing experience with it, and for some patients its tolerability profile suits them better. There is also the question of what you qualify for.

Both medicines are licensed privately for adults with a BMI of 30 or above, or 27 or above with a weight-related condition such as high blood pressure, high cholesterol or obstructive sleep apnoea. Lower BMI thresholds apply for some ethnic backgrounds under UK guidance. Neither medicine is suitable during pregnancy, breastfeeding or for anyone under 18.

On the NHS, eligibility for tirzepatide is phased, our treatment overview covers the current and upcoming cohorts in plain language. Wegovy is available via specialist weight management services under NICE's guidance, though waiting lists are commonly long. Most people who come to us have already weighed up those routes and decided private treatment is the right fit for now.

On price: Mounjaro's UK list price rose significantly in September 2025, and both medicines now sit in a similar private market range, typically £149 to £375 per month by dose and provider, as widely reported. If you're curious why the pricing differs between the two, the reasons Wegovy is often cheaper than Mounjaro come down to supply chain dynamics more than clinical value. Worth reading before you decide the cheaper option is automatically the smarter one.

So which medicine is right for you?

That is genuinely a clinical question, not something a comparison table can settle. Our prescribers look at your full picture (BMI, medical history, any current medicines, lifestyle, previous treatment if relevant) and then recommend the medicine and starting dose that makes sense for you. There is no algorithm. A named, GPhC-registered prescriber reads your consultation and responds the same day.

Some people come to us already set on one medicine; others prefer to be guided. Either way, the consultation is free, and there is no pressure to proceed. If payday falls awkwardly or you want to order before the bank holiday, the 12pm same-day dispatch cut-off applies Monday to Friday, so timing is always worth a quick check on the treatment page.

For a deeper read before you decide, the Mounjaro versus Wegovy comparison and the question of whether Mounjaro is more effective both go into further detail on the evidence. And if you've seen claims that Wegovy simply isn't as effective, that page gives the nuance those headlines often miss. Our clinical team oversees every prescription, and the FAQs cover the questions that come up most often. When you're ready, start your free consultation and a prescriber will take it from there.