Mounjaro®
Starting from £179.99/mo
Start journey Learn moreThe factors that shape the Mounjaro vs Wegovy switching decision
What you are actually choosing between
Mounjaro (tirzepatide, made by Eli Lilly) works on two gut-hormone receptors simultaneously — GIP and GLP-1 — making it the only dual-agonist weight-loss medicine licensed in the UK. Wegovy (semaglutide, made by Novo Nordisk) acts on the GLP-1 receptor alone. Both slow gastric emptying and reduce appetite; the mechanisms overlap but are not identical, which is part of why some people respond differently to each.
In the SURMOUNT-5 trial, published in the New England Journal of Medicine in 2025, tirzepatide produced greater average weight reduction than semaglutide 2.4mg over 72 weeks in adults with obesity and no diabetes. That said, the NICE appraisal of tirzepatide (TA1026) notes that indirect comparisons favour tirzepatide but that individual responses vary. A trial average does not predict your outcome.
One practical difference worth knowing before you switch: Mounjaro is injected once weekly from a KwikPen kept in the fridge door; Wegovy uses a different pre-filled pen, also weekly and refrigerated. The routine is broadly similar. What changes is the molecule, the titration schedule, and, for some people, the side-effect experience. People switching from Wegovy to Mounjaro are often chasing stronger results; people switching the other way sometimes find Wegovy's side-effect profile easier to tolerate at certain doses. Neither pattern is universal.
If you want a structured side-by-side breakdown of both medicines, the Wegovy vs Mounjaro comparison on this site covers efficacy, dosing timelines and eligibility in full.
| Factor | Mounjaro (tirzepatide) | Wegovy (semaglutide) |
|---|---|---|
| Receptor target | Dual GIP + GLP-1 | GLP-1 only |
| Licensed UK strengths | 2.5, 5, 7.5, 10, 12.5, 15 mg | Up to 2.4 mg (7.2 mg pen approved Apr 2026) |
| Average weight loss in trials | ~20–21% at 15 mg (SURMOUNT-1, NEJM) | ~15% at 2.4 mg (STEP 1, NEJM); ~20.7% at 7.2 mg |
| Head-to-head evidence | Greater average loss vs semaglutide 2.4 mg (SURMOUNT-5, NEJM 2025) | 7.2 mg narrows the gap; dedicated pen approved 14 Apr 2026 |
| Oral option available | No | Yes, Wegovy tablets (MHRA-approved June 2026) |
| UK licence (weight management) | BMI ≥30, or ≥27 with a weight-related condition | BMI ≥30, or ≥27 with a weight-related condition |
Why people switch, and what the evidence actually says
Supply disruption has driven many switches over the past two years. When a specific pen strength is unavailable, a prescriber may recommend moving to the alternative medicine rather than leaving someone without treatment. That is a pragmatic clinical call, not a reflection of one medicine being categorically superior.
Side effects are the other common driver. The gastrointestinal profile of both medicines (nausea, loose stools, occasional vomiting, reflux) is broadly similar in character, but individual tolerance varies. Some people find they handle one molecule better than the other. That is a legitimate reason to discuss a switch with your prescriber; it is not a reason to make the change unilaterally. The evidence on whether switching from Mounjaro to Wegovy produces continued results depends heavily on where in the titration schedule each person is and why the switch is being made.
Switching to semaglutide from tirzepatide mid-treatment also raises a practical question about where to start on the new medicine's schedule. The prescriber decides, not a dose calculator, not a forum recommendation. If you have read accounts on community forums about switching from Mounjaro to Wegovy, treat them as starting points for a conversation with a clinician, not as a protocol.
The NHS England guidance on weight-management injections provides useful context on both medicines in the broader clinical picture.
What a switch involves in practice at nume
At nume, every prescription is clinically reviewed, including transfers and switches. A GPhC-registered Independent Prescriber reads your consultation responses and checks evidence of your current treatment and dose before approving anything. There are no shortcuts here, and that applies just as much to switching from Wegovy to Mounjaro as it does to the reverse.
If you are already on Mounjaro through another provider and want to transfer, or if you are currently on Wegovy and want to discuss moving across, the process starts with a free consultation. You will be asked about your current dose, how long you have been on it, your experience so far and your reason for considering the change. That information goes to a prescriber the same day. You can read more about switching back to Mounjaro from Wegovy if you have previously been on tirzepatide and are considering returning to it.
Cost context: since Eli Lilly raised Mounjaro's UK list price in September 2025, private prices for both medicines typically fall in a similar range depending on dose and provider, roughly £149–£375 per month as widely reported. For a more detailed breakdown, the Mounjaro vs Wegovy cost comparison works through what those figures include and what they do not. At nume, one transparent price covers the consultation, prescription, treatment and free next-working-day delivery. Which medicine that applies to is determined by your prescriber, not by the price tag.
Which option suits you is a clinical decision our prescribers make with you, not something we can answer in a comparison table. Check your eligibility and start your free consultation to get a prescriber's view on your specific situation.
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