Thinking About Transitioning from Mounjaro to Wegovy? Here's What the Evidence Says

You've been doing well, or not quite well enough — and now you're weighing your options

Perhaps Mounjaro has worked well but supply has been patchy in your area. Perhaps you started on Wegovy, saw good early progress, and have since heard about tirzepatide's results. Or maybe your prescriber has raised the question of switching direction (from Wegovy to Mounjaro) and you want to understand what that comparison actually looks like before your next conversation. That uncertainty is entirely understandable, and the honest answer is that both medicines are effective, licensed, and meaningfully different in how they work.

Mounjaro (tirzepatide) activates two gut-hormone receptors (GIP and GLP-1) which is why it is described as a dual agonist. Wegovy (semaglutide) targets only the GLP-1 receptor. Both slow gastric emptying, reduce appetite and influence how the body regulates blood sugar, but the dual-receptor action of tirzepatide produces a different physiological effect, and the trial data reflects that. The head-to-head evidence between tirzepatide and semaglutide is worth reading alongside this page for the fuller picture.

Neither medicine should be started, stopped or swapped without a prescriber making that call. These are prescription-only medicines; the clinical review is the point, not a formality around it.

What the trial data shows, and what it doesn't settle for you personally

The SURMOUNT-1 trial (2,539 adults with obesity, no diabetes, 72 weeks) reported an average body-weight reduction of around 20–21% at the 15mg tirzepatide dose, published in the New England Journal of Medicine. The STEP 1 trial for semaglutide 2.4mg (68 weeks) reported approximately 15% average reduction. In the SURMOUNT-5 open-label head-to-head trial (72 weeks, 751 adults with obesity), tirzepatide produced greater average weight reduction than semaglutide 2.4mg, the clearest direct comparison available.

NICE acknowledged this in its appraisal of tirzepatide (TA1026), noting that indirect comparisons favoured tirzepatide. That said, the gap narrows with Wegovy 7.2mg, a higher maintenance dose approved by the MHRA in January 2026, with trial data showing around 20.7% average weight loss over 72 weeks.

The side-effect profiles of both medicines are broadly similar: nausea, digestive discomfort, and changes in bowel habit are the most commonly reported, particularly after starting treatment or following a dose increase. They generally settle within days to a couple of weeks. For further detail on what to expect, this comparison of Wegovy and Mounjaro goes deeper into the tolerability data.

What switching actually involves in practice

Transitioning from Mounjaro to Wegovy (or from Wegovy to Mounjaro) is not as simple as swapping one pen for another the following week. The doses do not correspond directly between the two medicines, and your prescriber will need to consider what dose to start you on in the new treatment, how quickly to titrate, and whether any washout period is appropriate. There is no single protocol that applies to everyone.

At nume, a switch is treated with the same level of clinical review as a new start. Our GPhC-registered Independent Prescriber will ask for evidence of your current treatment, review your recent weight history, and assess your full medical picture before deciding whether and how to proceed. The same ID verification and live weight check that applies to new patients applies here. You can explore what that process involves on our treatment page, or read about our clinical team's approach on the clinical team profile.

One thing worth knowing: NHS eligibility criteria for these two medicines differ. Mounjaro is recommended by NICE under TA1026 for adults with a BMI of 35 or above and at least one weight-related condition, within an NHS phased rollout. Wegovy falls under TA875, which requires a specialist weight management service and has a maximum two-year treatment duration attached to it. The Wegovy vs Mounjaro page covers the NHS access picture in more detail. Privately, the licensed eligibility is broader: BMI 30 or above, or 27 or above with a weight-related condition, for both medicines, but the prescriber's clinical assessment still applies regardless of which route you take.

Which medicine is right for you, and how that decision gets made

There is no universal answer to whether Mounjaro or Wegovy is the better fit for a given person. The trial data gives a population average, not a personal prediction. Factors a prescriber weighs include your response to whichever medicine you are currently on, how well you tolerated it, any relevant medical history, and what outcomes matter most to you. Cost and practical considerations (including pen availability) are also legitimate parts of that conversation.

If you are currently on Wegovy and are curious about switching to Mounjaro, or the other way around, the right starting point is a clinical conversation. Stopping treatment abruptly, or starting a new one at the wrong dose, carries real risks. The practical guide to going from Mounjaro to Wegovy and our overview of the switch process have more detail on the specific steps involved. For cost considerations between the two, this page compares the pricing context.

Which medicine suits you is a clinical decision our prescribers make with you, not something this page, or any page, can settle on your behalf. If you're ready to have that conversation, check your eligibility and start your free consultation.