Mounjaro®
Starting from £179.99/mo
Start journey Learn moreHow Mounjaro compares with other licensed GLP-1 options in the UK
The misconception: 'GLP-1' is a single category where stronger always means better
Most search results lump all GLP-1 medicines together as though they were interchangeable. They are not. Mounjaro activates two receptors simultaneously (GIP as well as GLP-1) while semaglutide (Wegovy) acts on GLP-1 alone. That biological difference is part of why the average weight losses seen in trials diverge. It is also why saying one medicine is simply 'better' collapses a clinical comparison into marketing language.
The question worth asking is not 'which is best in the abstract' but 'which is appropriate for this person, at this point in their health'. That is the conversation our prescribers have every day. Mounjaro's mechanism and licensed use in the UK is worth understanding before comparing it with anything else, because the dual-agonist distinction shapes nearly every comparison below.
It is also worth being clear about what is not in this comparison. Ozempic is semaglutide, but it is licensed in the UK for type 2 diabetes, not weight loss. Prescribing it for weight management is off-label, and it is not something a regulated UK weight-loss service should be offering. Any comparison between Ozempic and Mounjaro for weight loss is therefore a comparison between a licensed option and an unlicensed one, worth knowing before you read those articles.
What the head-to-head evidence actually shows
The SURMOUNT-5 trial is the only published randomised head-to-head study comparing tirzepatide directly with semaglutide 2.4mg for weight loss. Over 72 weeks, in 751 adults with obesity and no diabetes, tirzepatide produced a greater average weight reduction than semaglutide 2.4mg. NICE's appraisal of tirzepatide (TA1026) noted that indirect comparisons also favour tirzepatide, though the committee acknowledged the uncertainty inherent in indirect methods.
Semaglutide 2.4mg (Wegovy) is not without strong evidence of its own. The STEP 1 trial recorded around 15% average weight reduction over 68 weeks, and a higher 7.2mg dose (approved by the MHRA in early 2026) showed approximately 20.7% average loss, which narrows the gap with tirzepatide at its highest dose considerably. If you are also weighing up where older GLP-1 medicines such as exenatide sit in relation to tirzepatide, our comparison of exenatide and tirzepatide sets out how those two treatments differ.
You can review how other medicines compare with tirzepatide more broadly if you want a wider lens on this, or explore which treatments people consider when asking if something beats Mounjaro. Neither page will give you a single winner, and that is deliberate. The table below sets out the key factual differences.
| Factor | Mounjaro (tirzepatide) | Wegovy injection (semaglutide) |
|---|---|---|
| Mechanism | Dual GIP + GLP-1 agonist | GLP-1 agonist only |
| UK weight-loss licence | Yes (BMI ≥30, or ≥27 with a weight-related condition) | Yes (BMI ≥30, or ≥27 with a weight-related condition) |
| Average weight loss in trials | ~20–21% at 15mg over 72 weeks (SURMOUNT-1) | ~15% at 2.4mg over 68 weeks (STEP 1); ~20.7% at 7.2mg over 72 weeks |
| Head-to-head result | Greater average loss than semaglutide 2.4mg (SURMOUNT-5, NEJM 2025) | 7.2mg dose narrows the gap with tirzepatide 15mg |
| Administration | Once-weekly subcutaneous injection (KwikPen) | Once-weekly subcutaneous injection |
| NICE recommendation | TA1026 (Dec 2024, updated Sep 2025) | TA875 (Mar 2023); max 2 years within specialist services |
What the numbers cannot tell you
Trial averages describe populations. Your prescriber is interested in you, your starting weight, any comorbidities, medicines you already take, and how you respond to treatment over the first months. Some people tolerate one GLP-1 agonist better than another. Some have contraindications that rule one option out entirely. The side-effect profiles of tirzepatide and semaglutide are broadly similar (gastrointestinal symptoms, particularly early in treatment, are the most commonly reported) but individual experience varies.
Cost is a real factor too, and it deserves honest treatment. Private prices for both medicines have shifted notably; if that context matters to you, our guide to Mounjaro costs in the UK covers what legitimate private prescriptions typically include and why the cheapest listing is rarely the right test for a prescription medicine.
Retatrutide and other pipeline medicines are sometimes raised in these comparisons. Our prescribers are asked about them regularly, how retatrutide compares with Mounjaro is worth reading if that question came up for you, though neither is a decision you should reach without a full clinical assessment.
Which medicine is right for you, and how to find out
The clinical answer depends on a conversation, not a comparison table. Some people order on a Monday and have their treatment by Tuesday, orders placed before 12pm on a weekday are dispatched the same day once clinically approved. Others take longer because their picture is more complex, and that extra time is the right call.
At nume, a named GPhC-registered prescriber reads every consultation personally. They will consider both licensed options where appropriate, ask follow-up questions where needed, and issue a prescription only when the evidence supports it. If you want to understand the weight-loss treatment options available through nume before you start, that overview page covers both Mounjaro and Wegovy side by side. And if you would like a sense of who is reviewing your information, our clinical team profile is there to read.
Which medicine suits you best is a clinical decision, one our prescribers make with you, not for a generic version of you. Start your free consultation and find out.
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