Switching to Wegovy After Mounjaro: What the Evidence Actually Shows

You're midway through Mounjaro and wondering whether Wegovy would suit you better

It is a situation our prescribers encounter regularly. Perhaps you have read that Wegovy now comes in a 7.2mg dose and want to understand how that stacks up against the Mounjaro dose you are already on. Perhaps your circumstances have changed, or you are simply weighing your options before a renewal. Whatever the reason, the question is a sensible one, and there is a common misconception worth clearing up gently: many people assume the two medicines are interchangeable because both are weekly injections used for weight management. They are not the same drug, and switching is not as simple as adjusting a dose.

Mounjaro (tirzepatide) activates two gut-hormone receptors (GIP and GLP-1) which is why it is described as a dual agonist. Wegovy (semaglutide) works on the GLP-1 receptor alone. Both slow gastric emptying and reduce appetite, but the dual action of tirzepatide produces a meaningfully different hormonal response. That distinction matters when a prescriber is deciding whether switching makes clinical sense for you specifically.

If you are thinking about taking both at once, that is a separate question, and if you are wondering whether you can take Mounjaro and semaglutide at the same time, the short answer is that concurrent use is not supported. There is also more detail on the page about taking Mounjaro and Wegovy together.

What the trial data shows when you place them side by side

The SURMOUNT-5 trial, published in the New England Journal of Medicine in 2025, is the first large head-to-head comparison of tirzepatide against semaglutide 2.4mg in adults with obesity and no diabetes. Over 72 weeks, tirzepatide produced greater average weight reduction. NICE's appraisal of tirzepatide (TA1026) also notes that indirect comparisons favour tirzepatide over semaglutide at the doses previously studied.

Since then, Wegovy's picture has shifted. The MHRA approved a 7.2mg semaglutide dose in early 2026, and trials reported around 20.7% average weight loss at that dose over 72 weeks, considerably closer to the tirzepatide 15mg results. The table below summarises the key factual differences between the two medicines as they currently stand in the UK.

For a fuller side-by-side discussion of the two medicines, the Wegovy vs Mounjaro comparison covers the evidence in more depth.

What a prescriber looks at before agreeing to a switch

A prescriber reviewing a switch request will want to understand a few things: how long you have been on your current treatment, what dose you reached, how your body responded, and whether you experienced side effects that are driving the switch or simply a curiosity about whether the alternative might work better. Neither medicine is suitable for everyone, and clinical suitability is assessed individually.

Both Mounjaro and Wegovy are prescription-only medicines regulated in the UK under the Human Medicines Regulations 2012. NHS guidance on tirzepatide and the equivalent semaglutide page set out the standard side-effect profiles, both medicines have a broadly GI-led profile (nausea, changes to digestion, altered appetite), though individual experience varies considerably. Side effects on one may not predict your experience on the other.

Oral contraceptive users switching to or from Mounjaro should note that tirzepatide can reduce pill absorption during the first four weeks of treatment and after each dose increase; adding a barrier method during those windows is recommended by NHS guidance. Wegovy does not carry the same documented interaction with oral contraceptives. That kind of practical detail is exactly what a prescriber factors in during a switch review.

Cost is sometimes part of the conversation too. There is a genuine price difference between the two, and if that is on your mind, the page on why Wegovy is generally cheaper than Mounjaro explains the background. What a switch should never be is a cost-saving shortcut taken without clinical input.

How to explore a switch through nume

At nume, every prescription decision is made by a GPhC-registered Independent Prescriber. If you are an existing patient wanting to discuss a switch, our aftercare team is available seven days a week, you do not need to start from scratch. If you are new and coming from another provider, a transfer assessment looks at your current dose and treatment history before any new prescription is issued.

There is no algorithm making these calls. A prescriber reads your notes, considers the clinical picture and decides what is appropriate for you. That is true at the start of treatment and equally true when switching is on the table. You can find out more about how our clinical team approaches these decisions on the clinical team page.

Which medicine suits you best is a clinical decision, not a marketing one. Check your eligibility with our prescribers and the conversation starts from there.