Mounjaro®
Starting from £179.99/mo
Start journey Learn moreThe key factors that shape a switch from Wegovy 2.4mg to Mounjaro
What your decision actually hinges on
If you've reached the 2.4mg maintenance dose of Wegovy and your progress has slowed, the question isn't really "which pen is better" — it's whether a different mechanism might suit your physiology better at this point. Wegovy (semaglutide) activates one receptor pathway, GLP-1. Mounjaro (tirzepatide) activates two (GLP-1 and GIP) which is why clinicians sometimes describe it as working through a broader hormonal signal. That dual action is the main pharmacological reason someone on a plateau might be offered tirzepatide instead.
The other factor is where you are in the dose ladder. Mounjaro starts at 2.5mg and is titrated up by your prescriber, typically in monthly steps. If you switch from Wegovy 2.4mg, you don't begin at an equivalent therapeutic level, you restart at the bottom of the Mounjaro schedule to let your system adjust. Our page on how the dose conversion works in practice covers why a like-for-like swap isn't how the clinical maths operates.
Timing matters too. A switch mid-month, before a repeat order, or just before a holiday can disrupt the supply chain unnecessarily, many people find it cleaner to plan the change at a natural prescription renewal point, for instance aligning with payday or the start of a new month when it's easy to track. Your prescriber can advise on the washout timing.
What the trial evidence actually shows, and what it doesn't settle
In the SURMOUNT-1 trial (2,539 adults with obesity, 72 weeks), tirzepatide at its highest dose produced an average body-weight reduction of around 20–21%, as published in the New England Journal of Medicine. The STEP 1 trial for semaglutide 2.4mg showed around 15% average reduction over 68 weeks. In the SURMOUNT-5 head-to-head study (751 adults, 72 weeks), tirzepatide produced greater average weight loss than semaglutide 2.4mg, the most direct comparison available.
Those are population averages. Individual responses vary considerably. Some people lose more weight on semaglutide; some find tirzepatide's side-effect profile harder to tolerate. The newer comparison between Wegovy 2.4mg and Mounjaro is also shifting as Wegovy's 7.2mg dose enters the picture, and if you're wondering whether Wegovy 2.4mg has a meaningful equivalent on the Mounjaro scale, that's a question worth exploring before you decide. Worth reading about if you're mid-decision.
| Factor | Wegovy (semaglutide 2.4mg) | Mounjaro (tirzepatide, up to 15mg) |
|---|---|---|
| Mechanism | GLP-1 receptor agonist | GIP + GLP-1 dual receptor agonist |
| Average weight loss in trials | ~15% at 2.4mg (STEP 1, 68 weeks) | ~20–21% at highest dose (SURMOUNT-1, 72 weeks) |
| Maintenance dose | 2.4mg weekly (7.2mg pen now also approved) | Up to 15mg weekly, titrated by prescriber |
| If switching to Mounjaro | Treatment restarts at 2.5mg; no direct dose equivalence | |
| UK licence | Weight management (BMI ≥30, or ≥27 with condition) | Weight management (BMI ≥30, or ≥27 with condition) |
Side effects, tolerability, and what changes when you switch
Both medicines share a broadly similar side-effect profile: nausea, loose stools, constipation, reflux and fatigue are the most commonly reported, and they tend to be strongest in the first few weeks after starting or increasing a dose. The NHS patient page for tirzepatide covers the full list clearly.
When you switch from Wegovy to Mounjaro, the gut-hormone signalling changes, and GI symptoms can resurface even if you'd settled on semaglutide. Starting at 2.5mg helps manage that, but it's not a guarantee of a smooth first few weeks. One practical difference that matters for some patients: tirzepatide can reduce absorption of oral medicines (including the contraceptive pill) in the first four weeks of treatment and after each dose increase. An additional non-oral contraceptive method is recommended during those windows. Our FAQs include a section on contraception and GLP-1 medicines if you want more detail before your consultation.
Pancreatitis is an infrequent but potentially serious risk with GLP-1 medicines generally. Severe, persistent stomach pain that radiates to the back is a reason to seek urgent medical help, not to wait it out. The MHRA highlighted this in a Drug Safety Update in January 2026, side effects from either medicine can be reported at the MHRA Yellow Card scheme.
How a prescriber makes the call, and how the nume consultation works
A switch from 2.4mg Wegovy to Mounjaro isn't a decision a prescriber makes on mechanism alone. They'll consider how much weight you've lost on semaglutide, how long you've been at maintenance dose, your current BMI, any conditions that affect eligibility (hypertension, dyslipidaemia, type 2 diabetes, obstructive sleep apnoea and cardiovascular disease all factor into the licensed criteria), and how you've been tolerating treatment so far. Transfer patients at nume provide evidence of their current treatment; dose increases after switching require the same.
If you want to understand how the two medicines are priced privately, our page on the cost difference between Wegovy and Mounjaro is a useful read before committing to a switch, private prices vary by dose and provider. For a broader view of the two treatments side by side, the full Wegovy vs Mounjaro comparison covers the clinical picture in more depth. Which medicine suits you is a clinical decision our prescribers make with you.
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