Switching Medicines: Converting from Mounjaro to Wegovy

Step 1, understand why these two medicines do not convert like-for-like

Mounjaro activates two gut-hormone receptors: GIP and GLP-1. Wegovy activates GLP-1 alone. Because the underlying mechanisms differ, the clinical effects (and the body's adaptation) are not directly equivalent at matching doses. If you are thinking through how a mounjaro to wegovy conversion actually works in practice, the starting point is understanding that you cannot simply map "5mg Mounjaro = X mg Wegovy" and expect the same response. The clinical differences between Wegovy and Mounjaro go beyond the number on the pen.

This matters practically because both medicines have their own titration ladders. Mounjaro runs from 2.5mg to 15mg across six steps; Wegovy's licensed schedule runs from 0.25mg to 2.4mg, with the newer 7.2mg pen now approved by the MHRA for eligible adults with obesity. A prescriber reviewing your switch needs to consider where you are on the Mounjaro ladder, how well you tolerated each dose increase, and what starting point on the Wegovy schedule gives your system the best chance of adjusting without unnecessary side effects. Rushing that re-titration is one of the most common problems our prescribers see in patients arriving from other services.

The dose equivalence question is covered in detail for those who want the full breakdown, but the core point here is simple: a switch is a clinical decision, not a calculation.

Step 2, know what the evidence says about each medicine before deciding

Both medicines have strong clinical trial data, and a clear-eyed look at the numbers is worth your time before any switch. In the SURMOUNT-1 trial, tirzepatide produced average body-weight reductions of around 20–21% at the 15mg dose over 72 weeks, among thousands of adults with obesity as published in the New England Journal of Medicine. Semaglutide 2.4mg produced around 15% average reduction in the STEP 1 trial over 68 weeks. Head-to-head, the SURMOUNT-5 trial (72 weeks, 751 adults with obesity) showed tirzepatide producing greater average weight loss than semaglutide 2.4mg, a finding that informed NICE's appraisal process.

That said, the gap narrows at the newer 7.2mg Wegovy dose. The MHRA approved the single-dose 7.2mg pen in April 2026, with trials reporting around 20.7% average weight loss over 72 weeks, close to tirzepatide's results at its highest doses. The head-to-head comparison page goes through the full evidence table if you want to read both trial datasets side by side.

Why switch from Mounjaro to Wegovy? Common reasons include tolerability (some people find the GIP component of tirzepatide drives more GI discomfort), availability, or a clinical decision that one pathway suits a specific health background better. None of these is a reason to switch without prescriber input, but they are legitimate questions to raise.

Step 3, check the practical details before you request a switch

A switch consultation is not just about picking a new pen. Your prescriber will want to understand your full picture: how long you have been on Mounjaro, your current dose, any side effects you experienced during titration, and your weight trend over recent months. If you have been on a higher Mounjaro dose and tolerated it well, restarting Wegovy at 0.25mg can feel like a significant step back, and it is, because your system needs to re-adapt to a different molecule. That re-titration period is real, and skipping steps to get back to a comparable dose faster is not the right approach.

One practical check you can do right now: pull up the GPhC pharmacy register entry for nume and confirm that premises registration 9012878 is live and accurate. It takes under a minute. Any legitimate online pharmacy offering a switch consultation should be equally easy to verify; if you cannot find a pharmacy on the GPhC register, that is a clear red flag.

It is also worth knowing that Ozempic (which is also semaglutide) is licensed for type 2 diabetes, not for weight management. The Mounjaro to Ozempic page clarifies that distinction fully, because the two are frequently confused. For weight management, Wegovy is the correct semaglutide product. NICE's appraisal of tirzepatide (TA1026) and NICE's recommendation for semaglutide (TA875) both set out the clinical criteria clearly if you want to read the official guidance yourself.

How a switch consultation at nume works

The process is straightforward. You complete a free online consultation, your answers go directly to one of our GPhC-registered Independent Prescribers the same day. They read your full history, including any current treatment you are transferring from, before making any prescribing decision. Transfer patients provide evidence of their existing treatment; dose decisions are based on clinical review, not on what you request. If Wegovy is appropriate and available, and you order before 12pm on a working day, your prescription is dispatched the same day and arrives free the next working day via DPD. The full guide to switching between these two medicines covers what to bring to the consultation if you are already on Mounjaro.

Which medicine suits your situation is a clinical decision. Our prescribers make it with you, not for you, but it does require that conversation. You can read more about the team behind those consultations on our clinical team page, or explore the full range of weight-loss treatments we support on our treatment overview. When you are ready to take the next step, start your free consultation here.