The difference between Mounjaro and Wegovy for weight loss

Step 1, understand how each medicine works in the body

Mounjaro contains tirzepatide, made by Eli Lilly. It is the only weight-loss medicine in the UK that acts on two receptors simultaneously: GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1). Both pathways are involved in appetite regulation and the slowing of gastric emptying, so the stomach empties more slowly, fullness arrives sooner and calorie intake falls. Being a dual agonist sets it apart from every other option currently available.

Wegovy contains semaglutide, made by Novo Nordisk. It targets only the GLP-1 receptor (the same mechanism used by older GLP-1 medicines) but at a higher dose than earlier formulations. It still slows gastric emptying and reduces appetite effectively; single-pathway does not mean ineffective. Most people find the side-effect profiles of Wegovy and Mounjaro broadly similar, dominated by gastrointestinal effects during titration.

One misconception worth clearing up: Ozempic is also semaglutide, but it is licensed for type 2 diabetes, not weight management. It is not the same product as Wegovy and should not be obtained for weight loss. If you want to understand how Ozempic and Mounjaro differ from each other, that question has its own dedicated page; this page focuses on the two medicines that are actually licensed for weight loss in the UK.

Step 2, look at what the trial evidence shows

Clinical trial results are the clearest way to compare the two. SURMOUNT-1 (72 weeks) found that tirzepatide produced an average body-weight reduction of around 20–21% at the highest dose, the results that led NICE to recommend it. The STEP 1 trial (68 weeks) found semaglutide 2.4mg produced an average reduction of around 15%. Both figures are from trials of adults with obesity without diabetes, with lifestyle support.

A direct head-to-head comparison followed. In the SURMOUNT-5 trial, published in the New England Journal of Medicine in 2025, tirzepatide produced greater average weight reduction than semaglutide 2.4mg over 72 weeks in adults with obesity. That is the closest thing we have to a definitive comparison on a like-for-like basis. The gap narrows at semaglutide's newer 7.2mg dose, approved by the MHRA in early 2026, which showed around 20.7% average weight loss in trials, approaching tirzepatide's figures at maximum dose.

Numbers alone do not settle the question. Individual response varies. Tolerability, existing health conditions, and which medicine a prescriber judges most suitable all matter. You can explore the main clinical differences between Mounjaro and Wegovy in more depth if the evidence question is your starting point.

Step 3, check the eligibility picture for each

For private prescribing, both medicines are licensed for adults with a BMI of 30 or above, or BMI 27 or above alongside at least one weight-related condition such as high blood pressure, high cholesterol, obstructive sleep apnoea or type 2 diabetes. Lower BMI thresholds apply for some ethnic backgrounds under UK clinical guidance. The licensed criteria are similar; which medicine fits also depends on your full medical history.

On the NHS the picture is different, and NICE's recommendations for each medicine carry different conditions. Mounjaro (TA1026, updated September 2025) is available via a phased NHS rollout, starting with BMI 40 and four or more qualifying conditions, read more on how NHS and private weight-loss treatment access compares. Wegovy (TA875) requires a specialist weight management service and is recommended for a maximum of two years. NHS waiting lists for both are substantial in most areas. Full eligibility details are on the NICE tirzepatide appraisal and the NICE semaglutide appraisal.

For private treatment through a GPhC-registered pharmacy, there is no referral and no waiting list, your consultation is reviewed the same day by a named prescriber who considers your full circumstances before any prescription is issued.

Step 4, weigh cost alongside the clinical picture

Price is worth factoring in, though it is rarely the right place to start with a prescription medicine. Since Eli Lilly raised Mounjaro's UK list price in September 2025, the top dose commands a list price of around £330 per four-week pen; typical private prices across the market run roughly £149–£375 a month depending on dose and provider. Wegovy sits in a broadly similar private-market range. If you want to understand how Mounjaro and Wegovy compare across dose, mechanism and practical use, that page covers the full picture; the price difference shifts as doses change, so a direct monthly comparison depends heavily on where you are in the titration schedule.

At nume, one price covers consultation, prescription, delivery and aftercare, no subscription, no auto-renewal, no hidden charges. You can see current treatment pricing on the treatment page. We are not trying to be the cheapest option on the market; we are trying to be a service a prescriber is proud to put their name to. Given that counterfeit weight-loss pens are a documented problem in the UK (the MHRA has reported large seizures of fake pens) verifying any pharmacy on the GPhC register before purchasing is the step that actually protects you. Our registration number is 9012878.

Which of these two medicines suits you is not a question a comparison page covering what sets Wegovy and Mounjaro apart can answer, and if you want a broader overview before that conversation, our page on the difference between Mounjaro and Wegovy is a useful place to start. It is a clinical decision, made with our prescribers after reviewing your health history, and that conversation starts with a free consultation.