Mounjaro®
Starting from £179.99/mo
Start journey Learn moreWhat the clinical trials and regulatory decisions tell us about both medicines
Trial results: what the published data actually showed
The clearest picture of how these two medicines compare comes from SURMOUNT-5, a 72-week open-label randomised trial published in the New England Journal of Medicine in 2025. It set tirzepatide (Mounjaro) directly against semaglutide 2.4 mg (Wegovy) in 751 adults living with obesity but without type 2 diabetes. Tirzepatide produced greater average body-weight reduction. That finding fed directly into NICE's technology appraisal of tirzepatide (TA1026), whose committee noted that indirect comparisons across the wider trial programme also favour tirzepatide.
Wegovy's own pivotal STEP 1 trial (68 weeks, 2.4 mg maintenance dose) reported an average weight reduction of around 15%. Mounjaro's SURMOUNT-1 trial at the 15 mg dose reported reductions of around 20–21% over 72 weeks. These are not directly comparable figures (different trial populations, durations and designs) but they set the broad scale of difference between the two, and our page on wegovy compared to mounjaro explores what those differences mean in practice.
One important update: the MHRA approved a higher Wegovy dose of 7.2 mg in January 2026, with a dedicated single-dose pen approved on 14 April 2026. Trials at 7.2 mg reported around 20.7% average weight loss over 72 weeks, which narrows the gap with tirzepatide's top dose considerably. The full Mounjaro vs Wegovy comparison covers that data in more detail.
How the two companies' products differ mechanically, and why it matters clinically
Novo Nordisk's Wegovy targets a single gut-hormone receptor: GLP-1. That pathway reduces appetite, slows gastric emptying and nudges blood-sugar regulation. It is well-established, the STEP programme involved thousands of participants across multiple countries, and semaglutide has a long clinical history in diabetes (as Ozempic) before its weight-management licence arrived. Worth noting: Ozempic is licensed for type 2 diabetes, not weight loss; the two products should not be conflated.
Eli Lilly's Mounjaro works across two receptors simultaneously, GIP and GLP-1. It is the only dual-agonist weight-loss medicine currently licensed in the UK. Whether that dual action explains the larger weight-loss figures seen in trials, or whether other factors (dose ceiling, patient population) play a part, is still being studied. The ingredient-level differences between the two are worth understanding before you commit to a treatment.
Both medicines are administered as once-weekly subcutaneous injections via pre-filled pens. Both start at a low tolerability dose and are titrated upward by the prescriber in roughly four-week steps. Side-effect profiles overlap substantially: nausea, constipation, diarrhoea, indigestion and fatigue are common to both, typically most prominent after starting or after a dose increase. If you want a granular breakdown of how those profiles differ, our wegovy vs mounjaro page sets out the key distinctions clearly, and you can find a more detailed look at how Wegovy's mechanism compares to Mounjaro's if that level of detail is useful.
At a glance: comparing key facts side by side
| Mounjaro (tirzepatide, Eli Lilly) | Wegovy injection (semaglutide, Novo Nordisk) | |
|---|---|---|
| Mechanism | Dual GIP & GLP-1 receptor agonist | GLP-1 receptor agonist |
| Average weight loss in pivotal trial | ~20–21% at 15 mg (SURMOUNT-1, 72 weeks) [NEJM] | ~15% at 2.4 mg (STEP 1, 68 weeks) [NEJM]; ~20.7% at 7.2 mg (72 weeks) |
| Head-to-head result | Greater average loss vs semaglutide 2.4 mg (SURMOUNT-5, NEJM 2025) | 7.2 mg dose narrows the gap significantly |
| UK licence (weight management) | BMI ≥30, or ≥27 with a weight-related condition | BMI ≥30, or ≥27 with a weight-related condition |
| NICE recommended? | Yes (TA1026 (published Dec 2024) | Yes) TA875 (published Mar 2023); max 2 years, specialist services |
| Oral option available? | No (injection only) | Yes (Wegovy tablets approved by MHRA June 2026 (25 mg maintenance) |
Eligibility, NHS access and how a private route differs
NICE recommends tirzepatide (TA1026) for adults with a BMI of 35 or above plus at least one weight-related comorbidity) with thresholds 2.5 kg/m² lower for South Asian, Chinese, Middle Eastern, Black African or African-Caribbean backgrounds. NHS access is being phased in gradually; the second cohort (BMI 35–39.9 with four or more qualifying conditions) activated in June 2026. The NHS England weight-management injections page sets out the current rollout in full.
NICE recommends semaglutide (TA875) only within specialist weight management services, for a maximum of two years. Waiting lists for those services are commonly long. For people who don't meet NHS criteria or don't want to wait, a regulated private pharmacy is the alternative, subject to a prescriber confirming suitability.
At nume, a GPhC-registered Independent Prescriber reviews every consultation personally. They consider both medicines against your health history. Our clinical team are available to discuss the options with you, and the treatment overview page gives a broader picture of what's available. For a full breakdown of how pricing differs between the two, the Mounjaro–Wegovy price comparison is a useful starting point.
Which of these two medicines suits you is a clinical decision our prescribers make with you, not a conclusion this page, or any manufacturer's marketing, can reach on your behalf.
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