Wegovy vs Mounjaro: how the two compare in the UK

Why "which is better" is the wrong first question

People land on this comparison expecting a clean verdict, and honestly, that's fair. When you've spent months on waiting lists or scrolling contradictory advice, you want someone to just tell you which pen to buy. We understand the pull of that. But treating Wegovy and Mounjaro as rivals with a fixed ranking misses how prescribing actually works.

Both medicines are licensed in the UK for the same broad purpose: weight management alongside a reduced-calorie diet and more physical activity, for adults with a BMI of 30 or above, or 27 and above with a weight-related condition such as high blood pressure, prediabetes or obstructive sleep apnoea. Lower BMI thresholds can apply for people from South Asian, Chinese, Middle Eastern, Black African or African-Caribbean backgrounds under UK guidance, because cardiometabolic risk rises at a lower BMI in these groups.

So the two overlap heavily on paper. Where they diverge is in the detail: how your body tolerates each, your medical history, what you're already taking, and how the doses are structured. That's why our prescribers treat the choice as a conversation rather than a coin toss. If you want a fuller walk-through of the practical trade-offs, our page on choosing between Wegovy or Mounjaro takes it slowly. The rest of this page gives you the facts to weigh, without pretending the answer is universal.

The core difference: one hormone pathway or two

Here's the mechanical distinction that everything else hangs off. Wegovy is a brand of semaglutide, made by Novo Nordisk, and it works as a GLP-1 receptor agonist. It mimics one gut hormone your body releases after eating, which slows how quickly your stomach empties and dampens appetite signals in the brain.

Mounjaro is a brand of tirzepatide, made by Eli Lilly, and it's a dual agonist. It activates the GLP-1 receptor and a second one, GIP, both involved in appetite and blood-sugar control. It's currently the only dual-action medicine of its kind licensed in the UK for weight management, according to the NHS's guidance on tirzepatide.

Does two pathways automatically mean more weight loss? Not as a rule you can lean on. The extra GIP action is part of why tirzepatide performed strongly in trials, but individual response varies enormously, and tolerability matters just as much as theoretical potency. Some people settle beautifully on semaglutide and struggle on tirzepatide, or the reverse. If the mechanism side interests you, our breakdown of the differences between Mounjaro and Wegovy goes deeper into how each one behaves in the body. Both are Black Triangle (▼) medicines, meaning the MHRA is gathering extra safety data on them.

What the head-to-head trial actually showed

This is where evidence beats anecdote. The clearest direct comparison comes from the SURMOUNT-5 trial, published in the New England Journal of Medicine in 2025. It was an open-label study running 72 weeks across 751 adults living with obesity but without type 2 diabetes, and it compared tirzepatide against semaglutide at its then-standard 2.4mg dose.

In that trial, tirzepatide produced greater average weight reduction than semaglutide 2.4mg. NICE's committee, in its appraisal of tirzepatide (TA1026), also noted that indirect comparisons pointed the same way. So if you're asking purely about average trial numbers at those doses, tirzepatide came out ahead.

But the picture has moved. In January 2026 the MHRA approved a higher 7.2mg maintenance dose of Wegovy, with trials reporting roughly 20.7% average weight loss over 72 weeks, approaching the results seen with tirzepatide 15mg. That higher dose narrows the gap the SURMOUNT-5 comparison exposed. It's a useful reminder that a single trial captures a moment, not a permanent hierarchy. If you like seeing the numbers laid out, our page comparing the Mounjaro and Wegovy trial results visualises them, and the underlying study detail is worth a read before drawing conclusions from headline percentages alone.

A factual side-by-side

Numbers help, so here's a plain comparison of the two as licensed in the UK. Treatment figures are averages from clinical trials, not promises about what any individual will experience.

Sources for those figures are the SURMOUNT-1 and STEP 1 trials in the New England Journal of Medicine and NICE's appraisals. One caveat worth holding onto: the highest doses drive the biggest average results, and not everyone reaches or tolerates them. Our guide to Wegovy and Mounjaro dosing explains how each ladder is climbed.

How the dosing schedules compare in practice

The two follow different escalation paths, and this matters more day-to-day than the mechanism. Mounjaro starts at 2.5mg once weekly. That first strength isn't there to treat your weight; it's there to let your gut settle before the dose climbs. Prescribers typically step it up in roughly four-week intervals through 5, 7.5, 10, 12.5 and up to 15mg, always guided by how you're tolerating it.

Wegovy begins lower, at 0.25mg weekly, and titrates through 0.5, 1.0 and 1.7mg toward its maintenance doses. With the newer 7.2mg approval, the ceiling has risen, though the starting point stays the same gentle 0.25mg to reduce early nausea.

Neither schedule is something you self-manage from a webpage. Timing of increases, what to do if a dose feels rough, and whether to hold at a level are all prescriber decisions, and the Patient Information Leaflet is your reference for the exact detail. We don't publish do-it-yourself titration instructions, because that's precisely the judgement a clinician is meant to apply to you specifically. If you're weighing which ladder suits your life, the honest starting point is our page on whether Wegovy or Mounjaro is better for different circumstances, and if you're already on one and curious about the other, switching from Mounjaro to Wegovy covers what that transition involves.

Side effects: more alike than different

Both medicines share a broadly similar side-effect profile, because both lean on the GLP-1 pathway. The common effects are gastrointestinal: feeling sick, being sick, loose stools or constipation, reflux, burping, plus tiredness, headaches and reactions at the injection site. These tend to be most noticeable when you first start or step up a dose, and for many people they ease within a couple of weeks.

There's a more serious signal to know. In January 2026 the MHRA issued a Drug Safety Update flagging acute pancreatitis as an uncommon but potentially serious effect of GLP-1 medicines. The warning sign is severe, persistent stomach pain that may spread through to your back, sometimes with vomiting. If that happens, seek urgent medical help rather than waiting it out. Suspected side effects can be reported through the MHRA's Yellow Card scheme.

Because tirzepatide can reduce how well the contraceptive pill is absorbed, women using oral contraception are advised to add a barrier method such as condoms for the first four weeks of treatment and for four weeks after each dose increase. NHS guidance notes there's no equivalent evidence of reduced pill effectiveness with semaglutide, which is a genuine practical difference between the two. Our detailed comparison of Wegovy and Mounjaro side effects unpacks the nuances, and there's a common question about whether Wegovy quietens food noise the way Mounjaro does.

Cost context in the UK, without the sales pitch

Private weight-loss treatment in the UK is priced per pen or per month, and it varies between providers by dose and by what's bundled in. For context, Eli Lilly raised Mounjaro's UK list price from September 2025, with the highest dose's list price rising from around £122 to around £330 per four-week pen. Reported private prices since then typically range from roughly £149 to £375 a month depending on dose and provider.

Headline prices often leave things out: the consultation, the prescription itself, delivery, and aftercare when a dose needs reviewing. That's the part worth scrutinising before comparing two figures side by side. We're deliberately not the cheapest option, and we're comfortable saying so, because one transparent price at nume covers your free consultation, prescription, treatment, free next-working-day tracked delivery and seven-day aftercare, with no subscription quietly renewing in the background.

For a prescription medicine, the lowest listing answers the wrong question anyway; a genuine supply chain and real clinical oversight are what actually keep you safe. If cost is your deciding factor between the two, our dedicated page on Wegovy versus Mounjaro cost lays out how to compare like for like, and current treatment pricing sits on our weight-loss treatments page.

NHS access versus a private route

Getting either medicine on the NHS is possible but tightly rationed. For tirzepatide, NICE (TA1026) sets a phased rollout: as things stand, it's for adults with a BMI of 40 or above plus four or more qualifying conditions from a defined list, with the criteria widening in stages over the coming years. Every NHS patient must also take part in wrap-around diet and activity support, and from April 2026 some GP practices can prescribe it, though participation is optional so availability varies by area.

Wegovy on the NHS runs through specialist weight management services under NICE TA875, capped at a maximum of two years of use, and waiting lists are commonly long. You can read the detail on NHS England's page about weight-management injections.

If you don't meet those thresholds, or you can't face the wait, a regulated private route is the alternative. At nume that means a free online consultation reviewed the same working day by a GPhC-registered Independent Prescriber, a real clinician reading your answers rather than an algorithm rubber-stamping them. We verify your identity with photo ID and confirm your weight on video. It's a legitimate path, and it's the same medicines from the licensed UK supply chain. Criteria differ in Scotland, Wales and Northern Ireland, so nation-specific rules may not match England's.

Who each medicine suits, and who neither suits

Licensed eligibility for both is broadly the same: adults with a BMI of 30 or above, or 27 and above with at least one weight-related condition. But meeting a BMI number never guarantees a prescription. Our prescribers look at your whole picture, including your medical history and anything you already take.

Certain histories mean these medicines need careful discussion or aren't suitable: a personal or family history of medullary thyroid cancer or MEN2, previous pancreatitis, and some gastrointestinal conditions. Neither is recommended if you're pregnant, breastfeeding, or trying to conceive, and if conception is part of your picture, our page on Mounjaro, Wegovy and pregnancy covers what you need to know before starting or continuing treatment. Neither is licensed for anyone under 18. The contraception point above is part of why conception plans matter to the conversation.

A frequent question is whether you can combine them or run them together. You can't, and you shouldn't try to; there's no benefit and real risk, which we explain on our page about taking Mounjaro and Wegovy together. Another honest topic people raise is weight regain after stopping, covered in our piece on why many users regain weight after treatment ends. If you're comparing across a wider field, our overview of Saxenda, Wegovy and Mounjaro sets them in context. As a footnote worth clearing up: Ozempic and Rybelsus are also semaglutide but are licensed for type 2 diabetes, not weight loss, so they don't belong in this comparison as weight-loss options.

How we'd help you decide

Reading all this, you might still want a straight answer. What we can give you instead is a good process. Which medicine suits you is a clinical decision our prescribers make with you, weighing your history, tolerance, goals and any interactions, rather than a rank we can print in advance.

The consultation is free and honest. If neither is right for you, we'll say so. If one clearly fits your circumstances better, our clinical team will explain why in plain terms. You can read about the clinicians behind nume and how our GPhC-registered pharmacy operates before you commit to anything.

Order by 12pm on a working day and, once you're clinically approved, your treatment is dispatched the same day and delivered free the next working day by DPD, tracked, in plain packaging that gives nothing away. No subscription, no auto-renewal; every repeat is clinically re-reviewed. If you'd rather browse the fuller topic first, our weight-loss overview and our look at Mounjaro and Wegovy reviews are good next steps. When you're ready, checking your eligibility takes a few minutes.