Mounjaro®
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Start journey Learn moreHead-to-head evidence, eligibility differences, and what belongs in a clinical conversation
What SURMOUNT-5 actually found when these two medicines competed directly
For years, clinicians compared Mounjaro and Wegovy using separate trials run in different populations under different conditions. That changed with SURMOUNT-5, a 72-week open-label trial published in the New England Journal of Medicine in 2025, which randomised 751 adults with obesity (no diabetes) to either tirzepatide at the maximum tolerated dose or semaglutide 2.4mg weekly. Tirzepatide produced greater average body-weight reduction, and if you want to dig into how the Mounjaro and Wegovy weight loss figures stack up across the key trials, we have pulled the data together in one place. NICE's appraisal of tirzepatide (TA1026) noted that indirect comparisons also favour tirzepatide, and SURMOUNT-5 confirmed the direction of that difference in a controlled head-to-head setting.
The earlier single-drug trials fill in the scale. SURMOUNT-1 (tirzepatide, 72 weeks, published in the New England Journal of Medicine) reported average body-weight reductions of around 20–21% at 15mg; STEP 1 (semaglutide 2.4mg, NEJM 2021) found around 15% over 68 weeks. Those figures come from different participant groups, so they are not a direct race, but they give a sense of scale.
One misconception worth setting aside gently: Wegovy's newer 7.2mg maintenance dose does narrow the gap. The MHRA approved a dedicated single-dose 7.2mg pen on 14 April 2026, and trials at that dose reported around 20.7% average weight loss over 72 weeks — much closer to tirzepatide territory. So the picture is not static. You can explore a detailed breakdown of what that means practically on the Mounjaro vs Wegovy comparison page.
How the two medicines compare side by side
The table below draws on published trial data and MHRA-approved prescribing information. Numbers are from clinical trial populations and reflect averages; individual results vary.
| Factor | Mounjaro (tirzepatide) | Wegovy (semaglutide) |
|---|---|---|
| Mechanism | Dual GIP and GLP-1 receptor agonist | GLP-1 receptor agonist |
| Highest licensed dose (UK) | 15mg weekly | 2.4mg weekly (7.2mg pen from Apr 2026) |
| Average weight loss at highest dose | ~20–21% (SURMOUNT-1, 72 weeks) | ~15% at 2.4mg (STEP 1, 68 weeks); ~20.7% at 7.2mg (72 weeks) |
| Head-to-head result | Greater loss vs semaglutide 2.4mg (SURMOUNT-5, NEJM 2025) | Narrowing gap at 7.2mg dose |
| UK licence for weight management | Yes (BMI ≥30, or ≥27 with a weight-related condition) | Yes (BMI ≥30, or ≥27 with a weight-related condition) |
| NICE recommendation | TA1026 (Dec 2024) | TA875 (Mar 2023); max 2 years, specialist services |
Patients researching the cost angle as well as the clinical one will find the Wegovy vs Mounjaro cost comparison a useful companion read.
Eligibility: where the two medicines take different paths
Both medicines carry the same headline BMI thresholds for private prescribing: adults with a BMI of 30 or above, or from 27 with at least one weight-related condition such as high blood pressure, raised cholesterol, type 2 diabetes, or obstructive sleep apnoea. Adjusted thresholds apply for some ethnic backgrounds under UK guidance. A prescriber looks at the full picture (medical history, current medicines, contraindications) not the number alone.
NICE's NHS-access criteria differ between the two. Tirzepatide (TA1026) is recommended for NHS use at BMI ≥35 with at least one qualifying comorbidity, with a phased rollout broadening over 2025–2027. Semaglutide (TA875) is recommended only within a specialist weight management service for a maximum of two years. Those are NHS rules; private prescribing follows the licensed indications and clinical assessment, which is the route nume operates. Our clinical team's approach sits within those licensed boundaries.
Tirzepatide carries a specific note for women taking oral contraceptives: an additional non-oral method (such as condoms) is advised for the first four weeks of treatment and for four weeks after each dose increase, because pill absorption may be reduced. Many patients also ask whether semaglutide performs as well as Mounjaro overall, and the honest answer is that the practical differences go beyond weight loss averages alone. This is one of several practical differences a prescriber will walk through with you, you can read more about our prescribing team at our clinical lead's profile.
Which medicine is right for you, and how to find out
Choosing between Wegovy and Mounjaro is not a consumer choice. It is a clinical one. The evidence gives a direction, but direction is not destiny: some people respond better to one GIP-plus-GLP-1 mechanism than the other, some have contraindications that rule out one option, and if you are weighing up whether Wegovy is as effective as Mounjaro for weight loss, the answer depends on which dose and which trial you look at. Some patients are better served by Wegovy's tablet form (oral semaglutide received MHRA approval in June 2026 as the UK's first licensed oral GLP-1 for weight management), and for those wondering more broadly whether Wegovy is as good as Mounjaro across all the factors that matter clinically, that question deserves a fuller answer than a single headline figure. For a broader look at the full treatment landscape, the treatment overview page sets out what is available and how the consultation works.
At nume, a GPhC-registered Independent Prescriber reviews your consultation the same day you submit it, your answers land on a person, not a processing queue. If you have questions before starting, the FAQs page covers the most common ones, and you can reach the team directly via the contact page. The answer to which medicine suits you comes from that clinical conversation, not from a comparison table.
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