Mounjaro®
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Start journey Learn moreHow Mounjaro and Wegovy doses sit alongside each other, and why the decision is more than arithmetic
The decision you're actually making: same drug, different routes, or different drugs altogether?
A question our prescribers hear most weeks goes something like this: "I'm on 1 mg Ozempic for diabetes, what would that be in Mounjaro?" It is a reasonable instinct, but it rests on an assumption the science does not support. Mounjaro (tirzepatide) activates both the GIP and GLP-1 receptors; Wegovy (semaglutide) acts on GLP-1 alone. Because the underlying receptor pharmacology differs, the dose numbers carry different units of biological effect. If you are wondering how 1 mg semaglutide relates to a tirzepatide dose, the milligram labels alone cannot answer that question any more than you would compare a litre of petrol with a litre of diesel by volume alone.
The decision that matters is which medicine is clinically suitable for you, at which starting dose, and that is precisely what a prescriber assesses. Understanding both schedules is a useful part of that conversation, so here is what the evidence actually shows, drawn from NICE technology appraisal TA1026 for tirzepatide and TA875 for semaglutide.
The two titration schedules laid out clearly
Both medicines start low to let your system adjust, then increase roughly every four weeks until you reach the highest dose your prescriber judges appropriate. The licensed UK schedules look like this:
| Step | Mounjaro (tirzepatide) | Wegovy injection (semaglutide) |
|---|---|---|
| Starting dose | 2.5 mg / week | 0.25 mg / week |
| Step 2 | 5 mg / week | 0.5 mg / week |
| Step 3 | 7.5 mg / week | 1.0 mg / week |
| Step 4 | 10 mg / week | 1.7 mg / week |
| Step 5 | 12.5 mg / week | 2.4 mg / week (standard maintenance) |
| Maximum dose | 15 mg / week | 7.2 mg / week (MHRA-approved, April 2026) |
Numbers aside, both schedules ask your body to do broadly the same thing at each stage: tolerate a small increase, then settle before the next one. The MHRA approved a 7.2 mg semaglutide maintenance dose in January 2026 and a dedicated single-dose 7.2 mg Wegovy pen in April 2026, narrowing the gap between the two medicines' maximum efficacy. Sources: MHRA approval announcement, 14 April 2026; BNF tirzepatide monograph.
What the trial results tell us, and why they do not translate into a conversion ratio
The SURMOUNT-1 trial (tirzepatide, 72 weeks) reported average body-weight reductions of roughly 20–21 % at 15 mg. The STEP 1 trial (semaglutide 2.4 mg, 68 weeks) reported around 15 % average reduction. In the head-to-head SURMOUNT-5 trial, published in the New England Journal of Medicine series of GLP-1 trials, tirzepatide produced greater average weight loss than semaglutide 2.4 mg over 72 weeks in adults with obesity and no diabetes. If you are considering how 2.4 mg semaglutide compares when moving to tirzepatide, the trial data show around 20.7 % average loss at 7.2 mg semaglutide, closer to tirzepatide's results, though the trials were run separately and a direct numerical comparison should be treated with caution.
None of those percentages tell you that, say, Mounjaro 7.5 mg equals Wegovy 1.7 mg. The titration steps exist for tolerability, not because each rung delivers a proportional slice of the maximum effect. Patients respond individually; two people on the same dose can have meaningfully different experiences. If you are weighing up Wegovy against Mounjaro more broadly, the evidence page covers the head-to-head data in full.
Switching between treatments: what this means in practice
If you are already on semaglutide and considering a move to tirzepatide, or the other way around, the dose you were taking does not determine the dose you start on with the new medicine. Prescribers assess your current weight, response to treatment, any side effects and your wider health picture. Most people switching medicines restart from the beginning of the new schedule, both for safety and to let the body adjust to a different mechanism.
For a closer look at specific cross-medicine dose questions, the Mounjaro to Wegovy dose conversion page covers the switching process, and if you want to explore how a semaglutide dose maps onto a tirzepatide equivalent in more detail, that page is a useful starting point. For the other direction, Mounjaro equivalent doses to Wegovy covers what a prescriber considers when someone moves from tirzepatide to semaglutide.
The short version: which medicine suits you, and at which dose, is a clinical decision our prescribers make with you, not a calculation you can do from a milligram table. If you are ready to have that conversation, check your eligibility with a free consultation.
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