Swapping from Mounjaro to Wegovy: what changes, what stays the same

Step 1, understand why people consider the switch (and why the direction matters)

The most common reasons someone looks at swapping Mounjaro to Wegovy come down to three things: tolerability, access, or cost. Some people find the gastrointestinal side effects of tirzepatide harder to manage than expected; others have a gap in supply at their current provider; a smaller group is curious whether semaglutide suits their body better. The reverse switch (moving from Wegovy to Mounjaro) is equally valid and often prompted by the head-to-head trial evidence published in the New England Journal of Medicine: in the SURMOUNT-5 study, tirzepatide produced greater average weight reduction than semaglutide 2.4mg over 72 weeks in adults with obesity but without diabetes.

Neither direction is inherently right. What matters is why you want to switch and whether the clinical picture supports it. If you are on, say, Mounjaro 10mg and tolerating it well with good early results, switching is unlikely to be what your prescriber recommends. If you are struggling at 5mg and wondering whether a single-receptor medicine suits you better, that is a different conversation, and our guide to whether Mounjaro or Ozempic is the right fit can help you think through the broader choice before speaking to a prescriber. Our clinical team page gives you a sense of the prescribers who review these cases every day.

One practical note: if you are planning around supply, keep in mind that delivery windows can shift over bank holidays and school breaks, so build a buffer into any transition timing rather than leaving yourself mid-switch over a long weekend.

Step 2, the clinical review before any switch is approved

Before a prescriber approves a switch in either direction, they need a clear picture of where you currently are. That means your current dose, how long you have been on it, your weight trajectory, any side effects, and the reason you want to change. For transfer patients, the consultation process at nume includes evidence checks, you will be asked to confirm your current treatment and dose rather than simply self-reporting.

The two medicines are not dose-equivalent in any straightforward way. Mounjaro's licensed UK schedule runs from 2.5mg up to 15mg; Wegovy's standard maintenance dose has been 2.4mg weekly, with a higher 7.2mg dose now also approved by the MHRA following the single-dose pen authorisation in April 2026. When switching, a prescriber will generally not simply map one dose onto the other, they consider your response, your tolerance history, and the appropriate starting point on the new medicine's own ladder, which is why our full guidance on swapping from semaglutide to tirzepatide walks through what that process looks like in practice.

The NHS England guidance on weight-management injections is a useful background read on what clinical oversight of these medicines involves. It applies to NHS pathways but the underlying clinical principles are the same in private practice.

Step 3, comparing the two medicines before deciding

A structured look at the differences helps frame the clinical conversation. The table below covers the main factual contrasts between Mounjaro and Wegovy as licensed weight-management medicines in the UK.

For a fuller side-by-side breakdown, the Wegovy vs Mounjaro comparison on this site covers mechanism, eligibility and cost context in more depth. Numbers above are clinical-trial averages; individual results vary and are never guaranteed.

Step 4, what happens after the switch is approved

Once a prescriber approves the switch, the new medicine typically starts at its own introductory dose rather than at the level implied by your outgoing dose. Your body has not encountered this receptor profile before, and beginning partway up the dose schedule without settling-in time raises the risk of the side effects both medicines share: nausea, diarrhoea, constipation, reflux, and fatigue are all common in the first weeks, as the NHS medicines page for semaglutide explains plainly.

The prescriber will want to review your progress after the transition, which is why clinical re-assessment before every repeat order matters, not just at the initial switch. People sometimes ask whether reading others' experiences of the same switch is a useful guide; it can be reassuring context, but individual responses to these medicines differ enough that someone else's timeline is not a reliable predictor of yours. Our dedicated page on how to swap from Mounjaro to Wegovy sets out the step-by-step process our prescribers follow, so you know what to expect before your consultation.

If your reasons for considering this switch are primarily about cost, a comparison of Wegovy and Mounjaro pricing in the UK sets out the market context honestly. One transparent price at nume covers consultation, prescription, delivery and 7-day aftercare (no add-ons) but cost alone is rarely the right basis for a medicine switch. Which treatment suits you is a clinical decision our prescribers make with you, not one made on a price comparison alone.