Mounjaro®
Starting from £179.99/mo
Start journey Learn moreHow tirzepatide and semaglutide dose ladders compare at the starting stage, and what that means for switching or comparing
Why 2.5 mg Mounjaro does not map to a single Wegovy dose
A question our prescribers hear most weeks is some version of this: if I am on 2.5 mg Mounjaro, what is that in Wegovy? The honest answer is that the figure itself is not translatable. Tirzepatide and semaglutide are different molecules acting on different receptor combinations. Mounjaro activates both GIP and GLP-1 receptors; Wegovy acts on GLP-1 receptors only. Their dose ladders were calibrated independently in separate clinical programmes. The milligram quantities reflect the pharmacology of each drug, not a shared scale.
At 2.5 mg, Mounjaro is at its starter rung, prescribed for the first four weeks specifically to reduce gastrointestinal side effects while the body acclimatises. It is not the dose at which meaningful weight loss is expected. Wegovy's equivalent starting point is 0.25 mg, also a tolerability dose, also not the maintenance target. So in functional terms the two starting doses share the same purpose, even though the numbers look nothing alike, and you can read more about what 2.5 mg Mounjaro corresponds to in Wegovy terms if you want a closer look at that comparison. For a fuller picture of how the two titration schedules compare across their full ranges, our dose conversion guide walks through each step.
The NHS describes tirzepatide's licensed schedule, including the 2.5 mg starting dose, in detail on the NHS tirzepatide medicines page, worth reading alongside any dose comparison.
What the clinical evidence says about comparing these medicines at equivalent stages
Head-to-head evidence matters here. The SURMOUNT-5 trial, published in the New England Journal of Medicine in 2025, compared tirzepatide directly against semaglutide 2.4 mg in adults with obesity over 72 weeks. Tirzepatide produced greater average weight reduction. NICE's appraisal of tirzepatide (TA1026) notes that indirect comparisons favour tirzepatide over semaglutide, while also acknowledging the evidence base continues to develop.
That said, Wegovy 7.2 mg, approved by the MHRA in early 2026, narrows the gap meaningfully, with trial data reporting around 20.7% average weight loss at 72 weeks, closer to tirzepatide's higher-dose results. Neither medicine wins universally: tolerability, your medical history, and how your body responds all influence which produces better outcomes for you. You can explore more about how these medicines compare across their full maintenance doses on our Wegovy vs Mounjaro comparison page.
The table below sets out where each medicine stands at the start of treatment, factually and without editorialising.
| Feature | Mounjaro 2.5 mg (starter) | Wegovy 0.25 mg (starter) |
|---|---|---|
| Molecule | Tirzepatide | Semaglutide |
| Receptor action | Dual GIP + GLP-1 agonist | GLP-1 agonist only |
| Purpose of this dose | Tolerability / acclimatisation | Tolerability / acclimatisation |
| Duration at this dose (typical) | ~4 weeks, per prescriber | ~4 weeks, per prescriber |
| Next step on the ladder | 5 mg | 0.5 mg |
| Maximum licensed dose (UK) | 15 mg | 2.4 mg (or 7.2 mg pen, MHRA-approved April 2026) |
Switching between Mounjaro and Wegovy: what the decision actually turns on
If you are considering switching rather than simply comparing, the clinical picture shifts again. Someone established on 2.5 mg Mounjaro who wants to move to Wegovy is not switching between equivalent doses, they are starting a different medicine from scratch, which means returning to a tolerability starting dose on the new drug. The timing, wash-out considerations, and clinical rationale all require prescriber input. How Mounjaro's higher doses map against Wegovy's 2.4 mg maintenance dose is a separate question, and one that matters more once you are past the starting phase. If you are further along your titration, our page on what dose of Wegovy is equivalent to 7.5 mg Mounjaro covers that mid-treatment comparison in detail.
Cost sometimes drives the switching question. There is a real price difference between the two medicines in the UK private market, and how Wegovy's cost compares to Mounjaro's depends on the dose you are on and the provider you use. Price is a legitimate factor. It is not, however, a substitute for the clinical conversation about which medicine suits your history, your other medications, and how your body is responding. Which suits you is a clinical decision our prescribers make with you. Speak to our prescribers to start that conversation, the consultation is free and reviewed personally the same day.
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