Mounjaro or Ozempic: Which Is Actually Licensed for Weight Loss in the UK?

Step 1, Understand what each medicine is licensed to do

Ozempic and Wegovy are both semaglutide made by Novo Nordisk, but they carry different UK marketing authorisations. Ozempic (0.5mg, 1mg, 2mg weekly injection) is licensed for type 2 diabetes. Wegovy (up to 2.4mg weekly, with a higher 7.2mg dose approved by the MHRA in January 2026) is licensed for weight management. Using Ozempic to treat weight is off-label: the dose is lower, the licence doesn't cover it, and a prescriber would need specific clinical justification. That distinction matters practically, not just on paper, because dosing and monitoring differ between the two products.

Mounjaro is a different medicine entirely. Tirzepatide activates both the GIP and GLP-1 receptors, whereas semaglutide targets GLP-1 alone. That dual action is why Mounjaro is described as a different class within the GLP-1 family, the only dual-agonist weight-loss medicine with a UK licence. Its weight-management authorisation covers adults with BMI ≥30, or ≥27 with at least one weight-related condition such as high blood pressure, high cholesterol or obstructive sleep apnoea. You can read more about how the two medicines sit in UK clinical practice on our explainer comparing Mounjaro and Ozempic directly.

The short practical upshot: if someone in the UK is looking for a licensed weight-loss injection, the real choice is between Mounjaro and Wegovy, and our guide to Ozempic and Mounjaro explains where Ozempic fits into that picture.

Step 2, Look at what the trial evidence actually shows

For semaglutide at the weight-loss dose (2.4mg weekly), the STEP 1 trial over 68 weeks found an average body-weight reduction of around 15% among adults without diabetes, published in the New England Journal of Medicine. That is the evidence base for Wegovy's weight-management licence, not Ozempic's diabetes trial data.

For tirzepatide, the SURMOUNT-1 trial (72 weeks, 2,539 adults with obesity) reported average weight reductions of around 20–21% at the 15mg maintenance dose, cited in NICE's appraisal TA1026. The SURMOUNT-5 head-to-head trial, published in the New England Journal of Medicine in 2025, compared tirzepatide directly against semaglutide 2.4mg over 72 weeks and found greater average weight loss with tirzepatide. The gap narrows with the newer Wegovy 7.2mg dose, which showed approximately 20.7% average loss in trials.

One table to put the numbers side by side:

Trial results are averages in selected study populations alongside lifestyle support, individual results vary, and no outcome is guaranteed. Ozempic's diabetes trial figures are not directly comparable to the weight-loss trial results above, which is another reason the licence distinction matters.

For a closer look at how Mounjaro and Wegovy sit against each other, our Wegovy vs Mounjaro comparison covers the evidence and eligibility criteria in more depth.

Step 3, Consider side-effect profiles and what they mean for you

Both medicines share a gastrointestinal side-effect profile. The most commonly reported effects are nausea, diarrhoea, constipation, indigestion, burping and fatigue. These tend to be most noticeable after starting treatment or after a dose increase, and they often settle within days to a couple of weeks. Injection-site reactions and headache are also reported with both.

The MHRA issued a Drug Safety Update in January 2026 drawing attention to acute pancreatitis as an infrequent but potentially serious effect across GLP-1 medicines: severe or persistent stomach pain that radiates to the back, with or without vomiting, needs urgent medical assessment. That applies to tirzepatide and semaglutide products alike.

Neither is recommended during pregnancy, while breastfeeding, or when actively trying to conceive. Both are contraindicated in under-18s. Women using oral contraceptives starting tirzepatide should add a non-oral method for the first four weeks of treatment and for four weeks after each dose increase, because tirzepatide can reduce pill absorption; NHS guidance does not flag the same concern for semaglutide products. That is a meaningful practical difference between the two medicines worth raising at consultation, and if you are weighing up both options it is also worth reading our detailed look at Ozempic v. Mounjaro before speaking to a prescriber. A prescriber can walk through the full side-effect picture for your situation; the Patient Information Leaflet for each medicine carries the complete detail.

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Step 4 (Know what the licensed UK route looks like

Ozempic cannot be prescribed for weight loss through a legitimate UK private weight-management service) a prescriber has no licence-compliant basis to use it for that purpose when weight-loss-licensed alternatives exist. So if you came here asking about Ozempic for weight loss, the honest answer is: the medicine you're probably thinking of is either Wegovy or Mounjaro, and our page on whether you can take Wegovy with Mounjaro is worth reading if you have been wondering about combining them.

At nume, our prescribers review Mounjaro consultations personally, a real clinician reads your answers the same day (if you submit before noon on a working day, dispatch happens the same afternoon via DPD). The clinical team profile on our lead prescriber's page gives you a sense of who's doing that reviewing. More detail on both treatment options, including current pricing, is on the treatment overview page. If you want to see how Mounjaro and Wegovy prices stack up against each other, our cost comparison page lays that out without the marketing noise.

Which of the two licensed medicines is right for you is a clinical decision made with a prescriber, not a comparison article. Our team is available seven days a week if questions come up after you start.