Mounjaro®
Starting from £179.99/mo
Start journey Learn moreHow a Wegovy-to-Mounjaro switch works in the UK: the process, the dosage comparison, and the evidence
Step 1, Understand what you are actually switching between
There is a common misconception worth clearing up gently: some people arrive at this search believing Zepbound is a separate medicine that might be available in the UK, perhaps at a different dose or price. It is not. Zepbound is simply the name Eli Lilly uses in the United States for tirzepatide; the UK name is Mounjaro, and the medicine, the pen design, and the licensed doses are the same substance. Any dosage chart described as 'Wegovy to Zepbound' translates directly to 'Wegovy to Mounjaro' for UK patients.
That distinction matters because it affects which clinical guidelines apply. In the UK, Mounjaro's licensed strengths run from 2.5 mg through to 15 mg in six steps, while Wegovy's maintenance pathway tops out at 2.4 mg weekly (with a 7.2 mg higher-dose pen approved by the MHRA in April 2026 for eligible patients). The two medicines act on appetite and glucose regulation differently (semaglutide targets GLP-1 receptors alone, while tirzepatide activates both GLP-1 and GIP receptors) meaning they cannot simply be swapped milligram for milligram. You can read more about how the two medicines compare in our Wegovy vs Mounjaro overview.
This is the first step: knowing that the switch you are researching is a Wegovy-to-Mounjaro switch, governed by UK licensing and assessed by a UK prescriber.
Step 2, What the dosage chart actually shows (and what it cannot tell you)
A dosage comparison between semaglutide and tirzepatide is useful as orientation, not as a prescription. The table below sets out the licensed UK dose steps for each medicine alongside the trial weight-loss data associated with the highest maintenance doses, so you can see what you might be moving between.
| Medicine | Lowest UK dose | Standard maintenance | Higher-dose option | Average weight loss (highest dose, trial data) |
|---|---|---|---|---|
| Wegovy (semaglutide injection) | 0.25 mg/week | 2.4 mg/week | 7.2 mg/week (MHRA-approved Apr 2026) | ~15% at 2.4 mg (STEP 1, 68 weeks); ~20.7% at 7.2 mg |
| Mounjaro (tirzepatide injection) | 2.5 mg/week | Up to 15 mg/week | 15 mg (highest licensed UK strength) | ~20–21% at 15 mg (SURMOUNT-1, 72 weeks) |
Source: SURMOUNT-1, New England Journal of Medicine; STEP 1, New England Journal of Medicine; MHRA approval of 7.2 mg Wegovy pen, GOV.UK.
The SURMOUNT-5 trial (a direct head-to-head published in the New England Journal of Medicine in 2025) found tirzepatide produced greater average weight reduction than semaglutide 2.4 mg over 72 weeks in adults with obesity who did not have diabetes. The 7.2 mg Wegovy dose narrows that gap, and which outcome matters most for you personally depends on factors only a prescriber can weigh. Detailed dose-step comparisons are covered in our Wegovy vs Mounjaro dosage chart.
What the chart cannot show: it cannot account for your individual tolerance, your history on semaglutide, any side effects you experienced, or your prescriber's clinical judgement about where to restart. Those variables determine the actual starting dose, not the table.
Step 3, How a prescriber approaches the switch in practice
When someone moves from Wegovy to Mounjaro, a prescriber will typically review several things before recommending a dose. How long you have been on semaglutide and at which dose, how well you tolerated it, whether you experienced significant gastrointestinal effects, and how much weight you lost all inform where to begin on tirzepatide.
Mounjaro's 2.5 mg starting dose exists partly to let the body adjust to a new mechanism (the addition of GIP receptor activity) rather than simply to replicate the therapeutic effect of 2.4 mg semaglutide. Prescribers generally restart at 2.5 mg regardless of the dose you were on before, then titrate in four-week steps. This is the standard approach described in the Mounjaro SmPC, published on the electronic Medicines Compendium (eMC).
If you have been switching the other way, our page on switching from Mounjaro to Wegovy covers the equivalent process. For those already on Mounjaro who are considering semaglutide specifically, the Mounjaro-to-Wegovy dose conversion page goes into more clinical detail. And if cost is part of the decision, our Mounjaro and Wegovy price comparison sets out what each typically costs through a private service in the UK.
The consistent message from UK clinical guidance (including the NHS England weight management injections guidance) is that switches between GLP-1 or dual-agonist medicines should be managed with prescriber oversight, not self-directed.
What IS available in the UK, and how to explore a switch with a prescriber
Both Mounjaro and Wegovy are licensed for weight management in the UK and are dispensed by our GPhC-registered pharmacy. Zepbound, by contrast, exists only in the US market and is not obtainable through any UK pharmacy or clinical service. If you have seen references to Zepbound dosing online, those figures apply to a different regulatory context and should not be used as a guide for UK treatment.
For anyone thinking about switching from Wegovy to Mounjaro (or starting one of these medicines for the first time) our free consultation puts your question in front of a GPhC-registered prescriber, not software. A real clinician reads your answers the same day. If Mounjaro is clinically suitable, your prescription is written and your treatment is dispatched. You can also explore the broader range of weight-loss treatment options we offer, or read about moving from Wegovy 2.4 mg to Mounjaro specifically.
Which medicine is right for you is a clinical decision our prescribers make with you, based on your history, your health, and your goals, not on a dosage chart alone.
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