Mounjaro and Wegovy Compared: Making the Right Choice for You

The decision you're really making

Most people arrive at this comparison having heard one name more than the other, or having seen a headline about one drug outperforming the second. The honest framing is simpler than the noise suggests. Mounjaro and Wegovy both slow gastric emptying, reduce appetite and support clinically meaningful weight loss alongside a reduced-calorie diet. Where they differ is in their mechanism, their trial results, and the specific criteria under which a UK prescriber can lawfully offer them to you.

Mounjaro acts on two gut-hormone receptors (GIP and GLP-1) making it the only dual-agonist weight-loss medicine currently licensed in the UK. Wegovy activates GLP-1 receptors only. In practice, that biological difference shows up in the trial data, though neither medicine is appropriate for everyone, and the more impressive headline figure does not automatically make it the right choice for a given patient.

If you want to understand how the two compare on sales and clinical uptake across the UK, the Mounjaro and Wegovy sales comparison page covers what the prescribing data shows. This page focuses on the clinical picture.

What the evidence shows, and what it can't tell you about yourself

The trial results are worth stating plainly. In SURMOUNT-1, adults taking tirzepatide at the highest dose achieved an average body-weight reduction of around 20–21% over 72 weeks, published in the New England Journal of Medicine. In STEP 1, semaglutide 2.4mg produced approximately 15% average weight loss over 68 weeks in a comparable population. The SURMOUNT-5 head-to-head trial, also published in the New England Journal of Medicine in 2025, directly compared the two medicines in adults with obesity and no diabetes: tirzepatide produced greater average weight reduction over 72 weeks. NICE's appraisal of tirzepatide (TA1026) notes that indirect comparisons favour tirzepatide on weight outcomes, while acknowledging that direct evidence was limited at the time of appraisal.

Two things to hold alongside those figures. First, averages conceal wide individual variation, some people on Wegovy lose more than the mean tirzepatide figure; some on Mounjaro lose less than expected. Second, Wegovy's recently approved 7.2mg maintenance dose, assessed in trials reporting around 20.7% average weight loss at 72 weeks, narrows the gap considerably. If you'd like a thorough Mounjaro and Wegovy weight loss comparison covering how the two medicines stack up across different doses and trial populations, a dedicated page goes into the granular detail, including the weight-loss percentages for semaglutide and tirzepatide.

One practical note many patients raise: Mounjaro sits in the fridge door between uses, same as Wegovy. Both have a limited room-temperature window, the exact number of hours differs between the two, and for both it is the Patient Information Leaflet rather than any comparison page that carries the definitive answer.

Eligibility: where they overlap and where they part ways

The private licensed eligibility criteria are broadly similar. Both are indicated for adults with a BMI of 30 or above, or 27 and above where at least one weight-related health condition is present, hypertension, dyslipidaemia, type 2 diabetes, obstructive sleep apnoea and cardiovascular disease among the most common examples. Lower BMI thresholds apply for some ethnic backgrounds under UK guidance. A prescriber assesses the whole clinical picture: weight alone does not determine approval.

On the NHS the picture diverges more. NICE recommends tirzepatide under TA1026 for adults with a BMI of 35 or above and at least one weight-related comorbidity, through an NHS-phased rollout that is currently expanding. Wegovy on the NHS is available only through specialist weight management services, under TA875, for a maximum of two years. Waiting lists for both NHS routes are commonly long; private treatment through a regulated pharmacy is the alternative for people who qualify clinically but cannot access NHS provision quickly. The full eligibility comparison for Mounjaro and Wegovy sets out the detail.

If you are considering switching from one to the other, or have been on one previously, the Mounjaro to Wegovy guide covers what that transition looks like in practice.

Side effects, practical differences, and how to choose

The side-effect profiles of the two medicines overlap significantly. Nausea, diarrhoea, constipation, indigestion, burping, fatigue and injection-site reactions are well-documented for both, typically peaking around dose increases and easing over days to a couple of weeks. Pancreatitis is a known but infrequent risk with GLP-1 medicines; the MHRA issued a specific Drug Safety Update in January 2026 emphasising that severe stomach pain radiating to the back warrants urgent medical attention. Both carry Black Triangle status, meaning MHRA monitoring continues post-approval. The NHS tirzepatide page and the parallel semaglutide page carry the full patient-level side-effect information for each.

Practically, the injection technique and storage requirements are similar. One real difference is the oral option: Wegovy is now also available as a tablet (approved by the MHRA on 11 June 2026), which some patients find easier to manage than injections. Mounjaro has no equivalent oral form. If needle-free treatment matters to you, that changes the comparison.

On cost, tirzepatide's list price rose substantially from September 2025 and private market prices vary by dose and provider. A detailed look at how the two medicines compare on price sits on the tirzepatide vs semaglutide cost page. At nume, one transparent price covers everything (consultation, prescription, delivery and aftercare) with no subscription and no hidden charges. Our prescribers review your case before every repeat order. Which medicine makes sense for you is a clinical decision, and our team makes it with you. Start your free consultation and we'll work through the options together.