Is 0.25mg Wegovy the Same as 2.5mg Mounjaro? Starting Doses Compared

You've been told to start low, but low means something different for each medicine

Picture this: you've done your research, you're comparing Wegovy and Mounjaro side by side, and you notice that one starts at 0.25mg while the other starts at 2.5mg. It's natural to assume the Mounjaro figure represents a larger, stronger dose. It doesn't. The two numbers exist on entirely separate scales.

Wegovy (semaglutide) is a GLP-1 receptor agonist made by Novo Nordisk. Its dose ladder runs 0.25mg, 0.5mg, 1.0mg, 1.7mg and 2.4mg, with the recently approved 7.2mg as the highest maintenance option. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist made by Eli Lilly, the only medicine licensed in the UK that activates both of those gut-hormone pathways. Its dose ladder runs 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg. The different molecules have different potencies per milligram, so comparing 0.25 to 2.5 across brands is a bit like comparing kilometres to miles: the unit names look familiar but the scales don't line up. If you're wondering whether Wegovy 2.4mg and Mounjaro 2.5mg are the same, that question gets its own dedicated answer because the similarity in numbers causes genuine confusion. For a fuller overview of how the two medicines sit alongside each other, the Wegovy vs Mounjaro comparison on this site covers both in detail.

In both cases, the starter dose exists to settle your system, not to drive weight loss. Prescribers step the dose up every four weeks or so, assessing tolerance at each stage. The therapeutic work happens further up the ladder.

What the evidence shows at maintenance, not at the starting point

Neither the 0.25mg Wegovy nor the 2.5mg Mounjaro starting dose is what the clinical trial results were built on, so it helps to know what the maintenance figures actually show.

In the STEP 1 trial (published in the New England Journal of Medicine), participants on 2.4mg semaglutide lost around 15% of their body weight on average over 68 weeks. Tirzepatide's SURMOUNT-1 trial showed roughly 20–21% average reduction at the 15mg dose over 72 weeks. In the SURMOUNT-5 head-to-head trial, published in the NEJM in 2025, tirzepatide produced greater average weight loss than 2.4mg semaglutide over 72 weeks, a finding the NICE tirzepatide appraisal (TA1026) references when discussing indirect comparisons. That said, the newer 7.2mg Wegovy dose, approved by the MHRA in January 2026, narrows the gap considerably, reporting around 20.7% average loss in trials.

The table below sets out the key factual differences between the two starting doses in context.

For readers specifically curious about how the next steps compare, the 0.5mg Wegovy versus 5mg Mounjaro comparison looks at the second rung of each ladder, and 1mg Wegovy versus 10mg Mounjaro takes that further up.

A quick check you can do right now

If you're already on one of these medicines and wondering whether you're at the equivalent dose to a friend on the other, there is no reliable conversion table, the milligrams do not map across. A clinician can look at your current dose, your response so far and your medical history and give you a meaningful answer in minutes. That's a very different exercise from reading a number off a box.

One practical habit worth building: before any repeat order or dose change, pull up the GPhC register entry for your pharmacy and confirm it is still active. It takes under a minute and is the fastest way to verify you're dealing with a legitimate, regulated dispensing service. If the pharmacy isn't on that register, don't order from them, the MHRA has warned repeatedly about fake pens sold without any clinical oversight, some containing substances far more dangerous than the medicine on the label.

For a broader look at how dose progressions compare across the two treatments, the Mounjaro to Wegovy dose conversion page explores what switching can actually involve. And if cost is part of the picture, why Wegovy is priced differently to Mounjaro explains the market context without the spin.

Which starting dose is right for you is a clinical question

Choosing between Wegovy and Mounjaro isn't a matter of picking the one that starts at a more familiar-looking number. A prescriber will look at your BMI, your weight-related health conditions, any medicines you already take (particularly oral contraceptives, where tirzepatide carries specific guidance about adding a non-oral method for the first four weeks and after each dose increase), and your personal circumstances. Both medicines are licensed for adults with a BMI of 30 or above, or from 27 upwards with at least one weight-related condition. BMI alone doesn't determine suitability, that's what the consultation is for.

The weight loss treatment overview sets out both options side by side, and our clinical team handles every consultation personally. Which suits you is a clinical decision our prescribers make with you, not something a comparison article can settle. Speak to our prescribers through a free consultation and get a straightforward answer based on your actual situation.