Mounjaro®
Starting from £179.99/mo
Start journey Learn moreHow the 2.5mg Mounjaro and Wegovy starting doses sit within their respective schedules
Step 1, understand what each 'starter' dose is actually for
Mounjaro (tirzepatide, made by Eli Lilly) begins at 2.5mg. That first pen exists almost entirely to let your body adjust, the nausea, digestive grumbling and general unsettled feeling that some people get on GLP-1-type medicines is far less likely when the dose starts low. The NHS tirzepatide page describes this clearly: 2.5mg is the tolerability starting point, typically held for four weeks before a prescriber considers moving up.
Wegovy (semaglutide, made by Novo Nordisk) follows the same logic. It starts at 0.25mg for the first four weeks, then steps through 0.5mg, 1.0mg, 1.7mg, before reaching the standard 2.4mg maintenance dose. A common misconception is that 2.5mg Mounjaro and 0.25mg Wegovy are both 'starter doses, so they must be equivalent.' They serve the same purpose on their own schedules, but they are different molecules, different receptor targets, and different dose ranges entirely, the similarity ends at 'we both begin gently.'
If you want to think through how the full Wegovy schedule maps across, the Mounjaro-to-Wegovy dose conversion guide on this site works through the comparison in detail. The short version: there is no single conversion table that applies cleanly, because the two medicines are not interchangeable.
Step 2, compare the dose structures side by side
The table below sets out the licensed UK dose ladders for both medicines. Numbers are drawn from the respective Summary of Product Characteristics, referenced via the electronic Medicines Compendium (eMC).
| Feature | Mounjaro (tirzepatide) | Wegovy injection (semaglutide) |
|---|---|---|
| Starting dose | 2.5mg once weekly | 0.25mg once weekly |
| Dose steps | 2.5 → 5 → 7.5 → 10 → 12.5 → 15mg | 0.25 → 0.5 → 1.0 → 1.7 → 2.4mg (→ 7.2mg) |
| Standard maintenance | Highest tolerated dose up to 15mg | 2.4mg; 7.2mg now also approved |
| Receptor target | Dual GIP and GLP-1 agonist | GLP-1 agonist only |
| Injection frequency | Once weekly | Once weekly |
| Average weight loss at top dose (trial data) | ~20–21% at 15mg (SURMOUNT-1) | ~15% at 2.4mg (STEP 1); ~20.7% at 7.2mg |
A few things stand out. Tirzepatide's dose range runs from 2.5mg to 15mg, a sixfold increase from start to finish. Semaglutide's runs from 0.25mg to 7.2mg, which in milligrams sounds smaller but reflects a completely different molecule at a different potency per milligram. Comparing '2.5mg' to '2.4mg' as if they are near-identical doses misses that entirely.
For a closer look at how mid-range doses sit against each other, the Wegovy 2.4mg versus Mounjaro equivalence page covers the maintenance-dose comparison in the same format.
Step 3, what the evidence says about outcomes at each end of the scale
The SURMOUNT-5 trial, published in the New England Journal of Medicine in 2025, compared tirzepatide and semaglutide 2.4mg head-to-head over 72 weeks in adults with obesity and without diabetes. Tirzepatide produced greater average weight loss. That is the best direct comparison available, and NICE's appraisal of tirzepatide (TA1026) acknowledged indirect comparisons that favour it. The gap narrows at semaglutide's higher 7.2mg dose, which the MHRA approved in early 2026.
None of this tells you which medicine is right for you. Outcomes in trials are averages across thousands of participants; your response depends on your starting weight, your health history, how you tolerate each dose step, and factors a prescriber weighs up at consultation. The SURMOUNT-1 trial enrolled 2,539 adults (a large, well-powered study) but you are not the average participant.
People transferring between the two medicines sometimes ask about the 5mg Mounjaro step in particular. The 5mg Mounjaro and Wegovy equivalence page addresses that transition question specifically. And if you are curious how the mid-range Wegovy doses sit against Mounjaro, the Wegovy 1mg equivalent page is the relevant comparison, while those moving on to the 7.5mg Mounjaro step can find out which Wegovy dose is considered equivalent to Mounjaro 7.5mg before making any decisions about switching.
Step 4, what this means if you are deciding between the two
Which medicine a prescriber recommends comes down to your individual picture: BMI, comorbidities, any medicines you already take, how you feel about injections versus tablets (the oral Wegovy tablet is now also MHRA-approved for weight management), and your tolerance history. Neither medicine is 'better' as a blanket statement. The stronger average trial results for tirzepatide at high doses are real, but so is the fact that not everyone reaches the maximum dose, and not everyone responds the same way.
Cost is a separate consideration. Both are private prescriptions for most people right now. The price difference between Wegovy and Mounjaro page explains why the list prices differ and what that means in practice. It is worth reading before you assume price reflects quality.
At nume, our prescribers go through your consultation properly, your answers land with a named clinician, not a queue for automated processing. If you want to explore which treatment suits your situation, or you have been on one medicine and are wondering about switching, starting a free consultation is the right next step. There is no obligation and no hidden cost to finding out.
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