Mounjaro®
Starting from £179.99/mo
Start journey Learn moreHow the two medicines compare, and what actually drives the decision
The honest answer to 'is Wegovy as good as Mounjaro?'
A question our prescribers hear most weeks, in almost exactly those words. The short version: Wegovy works. Mounjaro, on average, works a little more. Whether that gap matters for you is a different question entirely.
The clearest evidence comes from SURMOUNT-5, a 72-week open-label trial in 751 adults with obesity and no diabetes, published in the New England Journal of Medicine (2025). Participants taking tirzepatide lost more body weight on average than those taking semaglutide 2.4mg, a finding that NICE also noted when appraising both medicines. Earlier, SURMOUNT-1 had shown average reductions of around 20–21% at tirzepatide's 15mg dose, while STEP 1 put semaglutide 2.4mg at roughly 15% average over 68 weeks. Those figures come from separate trials with different populations, so they aren't a clean head-to-head, but the SURMOUNT-5 data now provides that direct comparison.
One wrinkle worth knowing: Wegovy now comes in a higher 7.2mg dose, approved by the MHRA in April 2026, with trial data showing around 20.7% average weight loss over 72 weeks at that strength. That narrows the gap with tirzepatide considerably. So the question of whether Wegovy is just as good as Mounjaro is more nuanced in 2026 than it was a year ago.
Both medicines are prescription-only. A prescriber makes the call, not a comparison article.
Mechanism, tolerability and who tends to do well on which
Mounjaro activates two receptors: GIP and GLP-1. Wegovy activates GLP-1 only. That dual action is why tirzepatide is the only medicine of its kind licensed for weight management in the UK, and it partly explains the larger average weight loss in trials. Both slow gastric emptying, reduce appetite and affect blood-sugar regulation, so the day-to-day experience of being on either medicine has real similarities.
Tolerability matters as much as headline efficacy. Both carry a GI-led side-effect profile: nausea, diarrhoea, constipation and reflux are common, particularly after starting or a dose increase, and usually settle within a week or two. The NHS medicines page for semaglutide and the equivalent page for tirzepatide set out what to expect and when to seek medical advice. Neither medicine suits everyone, and some people find one tolerable where the other caused problems.
There are also practical differences worth discussing at consultation. For tirzepatide specifically, women taking oral contraceptives should use an additional non-oral method for the first four weeks of treatment and for four weeks after each dose increase, because pill absorption may be affected. NHS England's guidance on weight-management injections covers this, along with advice on HRT and surgery. The same absorption concern doesn't apply in the same way to semaglutide. That's the sort of detail that shapes a prescriber's recommendation for a specific person.
What the numbers look like side by side
A clean comparison of the headline trial figures, for context. These come from separate trials (SURMOUNT-5 is the only direct head-to-head) so treat the individual trial numbers as indicative rather than directly comparable.
| Factor | Mounjaro (tirzepatide) | Wegovy (semaglutide) |
|---|---|---|
| Mechanism | Dual GIP & GLP-1 agonist | GLP-1 agonist |
| Licensed UK doses | 2.5mg–15mg (once weekly) | 0.25mg–7.2mg (once weekly) |
| Average weight loss (pivotal trial) | ~20–21% at 15mg (SURMOUNT-1, 72 weeks) | ~15% at 2.4mg (STEP 1, 68 weeks); ~20.7% at 7.2mg |
| Head-to-head result | Greater average loss (SURMOUNT-5, NEJM 2025) | Lower average loss vs tirzepatide in SURMOUNT-5 |
| UK licence, weight management | Yes (BMI ≥30, or ≥27 with a weight-related condition) | Yes (BMI ≥30, or ≥27 with a weight-related condition) |
| Black Triangle status | Yes (additional MHRA monitoring) | Yes (additional MHRA monitoring) |
For a closer look at how cost factors into the decision alongside efficacy, the tirzepatide vs semaglutide cost page covers the pricing picture in detail.
Eligibility, access and how a decision actually gets made
Both medicines require a prescription following clinical assessment. On the NHS, eligibility criteria differ between the two: NICE's appraisal of tirzepatide (TA1026) sets thresholds around BMI and qualifying conditions for phased rollout in primary care, while NICE's appraisal of semaglutide (TA875) restricts it to specialist weight management services for a maximum of two years. NHS waiting lists exist for both. Private prescribing through a regulated online pharmacy is the route many people take when they don't meet NHS criteria or don't want to wait.
At a private consultation, your prescriber weighs your BMI, your health history, any medicines you already take, and your preference. The Wegovy vs Mounjaro comparison page goes deeper on those practical differences, and how semaglutide compares to Mounjaro more broadly covers the wider semaglutide picture, including Ozempic, which is licensed for type 2 diabetes, not weight loss, an important distinction that we explore further on our page looking at whether Ozempic is as good as Mounjaro. You can also read about our clinical team and the oversight behind every consultation.
The bottom line: Mounjaro produces greater average weight loss in trials. If you're weighing up what a Wegovy equivalent to Mounjaro actually looks like in practice, the 7.2mg dose has changed the conversation considerably. Which is right for you is a clinical decision our prescribers make with you. Check your eligibility and start your free consultation today.
Looking to start your weight loss journey?
Take a quick eligibility quiz to explore your options and see how we can support you.