Can you swap from Mounjaro to Ozempic for weight loss?

Why Ozempic cannot be prescribed for weight loss in the UK

This is probably the most common misunderstanding our prescribers encounter. Ozempic and Wegovy both contain semaglutide, made by Novo Nordisk, but they carry different UK marketing authorisations. Ozempic is licensed by the MHRA for glycaemic control in adults with type 2 diabetes. Wegovy is licensed for weight management in adults with a BMI of 30 or above, or 27 or above alongside a weight-related condition. The MHRA's public guidance on GLP-1 medicines is clear: these medicines are not assessed or authorised for cosmetic or incidental weight loss, and prescribing Ozempic off-label for weight loss in a private weight-management setting falls outside what a responsible prescriber should do. So the question of whether you can swap from Mounjaro to Ozempic for weight loss has a clean answer: not through any legitimate UK route. The medicine to ask about is Wegovy.

For a broader comparison of semaglutide and tirzepatide products, our Ozempic and Mounjaro overview covers the licensing landscape in detail.

How Mounjaro and Wegovy actually compare, and what the trial data shows

Mounjaro (tirzepatide, Eli Lilly) activates two gut-hormone receptors, GIP and GLP-1. Wegovy (semaglutide 2.4mg, Novo Nordisk) targets GLP-1 alone. That dual-pathway mechanism is relevant to the results. In SURMOUNT-1, published in the New England Journal of Medicine, tirzepatide at its highest dose produced average weight reductions of around 20–21% over 72 weeks in adults with obesity. The STEP 1 trial of semaglutide 2.4mg reported around 15% average reduction over 68 weeks. In the SURMOUNT-5 head-to-head trial (2025, NEJM), tirzepatide produced greater average weight loss than semaglutide 2.4mg directly. The newer Wegovy 7.2mg dose, approved by the MHRA in April 2026, has reported around 20.7% average loss over 72 weeks, which narrows that gap considerably. Neither trial declares a universal winner, individual response varies, tolerability differs between people, and the right medicine is the one that works for you at a dose you can sustain.

What a switch to a weight-loss medicine actually involves

If you are on Mounjaro and wondering whether to move to a semaglutide-based option, the relevant page is our guide on switching from Mounjaro to Wegovy, which walks through what a prescriber considers: how long you have been on your current medicine, what dose you have reached, how well it is working, whether side effects are driving the question, and whether there is a clinical reason to prefer a different mechanism. A switch is not a simple like-for-like substitution, and our detailed guide on moving from Mounjaro to Ozempic explains why the dosing schedules, starting doses, and tolerability considerations mean your prescriber needs to confirm suitability before any change. Timing and washout are not self-managed decisions. The NHS tirzepatide medicine page and its semaglutide equivalent both note that changes to treatment should be made with clinical guidance, not independently.

People sometimes wonder whether Ozempic is the same thing at a lower price. It is not: the doses used for diabetes are different from Wegovy's weight-management doses, and the clinical monitoring context differs too. Licensing exists for good reasons. For context on how the two weight-loss medicines compare side by side, our Wegovy vs Mounjaro comparison sets out the evidence clearly. If cost is part of your thinking, the price difference between Wegovy and Mounjaro has its own explanation. Which of these is right for you is a clinical decision, one our prescribers work through with you individually. Start your free consultation and we will review your details the same day.