Wegovy 0.25mg Compared to Mounjaro: What the Starting Doses Actually Tell You

Step 1: Understand what the starter dose is actually for

A question our prescribers hear most weeks is whether 0.25mg of Wegovy is 'stronger' or 'weaker' than Mounjaro's 2.5mg. The numbers look wildly different, but the two doses serve the same purpose: settling your digestive system before the real titration begins. Wegovy (semaglutide) and Mounjaro (tirzepatide) work differently at the receptor level, so their dose scales are completely separate and cannot be read against each other in milligrams.

Semaglutide activates the GLP-1 receptor; tirzepatide activates both the GIP and GLP-1 receptors. Because of those different mechanisms, the therapeutic windows are different, and the numbers on the pen are not a shared currency. Comparing 0.25mg Wegovy to 2.5mg Mounjaro as if they were on the same scale is a bit like comparing kilometres to miles, the unit means something different in each system. You can read more about how the two medicines work differently on our detailed 0.25mg Wegovy versus Mounjaro page.

What both starter doses share is intentional restraint. The prescriber sets the lowest rung deliberately; the goal for the first four weeks is tolerance, not weight loss.

Step 2: Map the full titration sequence side by side

Seeing both ladders together makes the structure clearer. The table below shows the licensed UK schedules for each medicine, with the approximate pace of titration per the Summary of Product Characteristics. Your actual titration is managed by your prescriber based on how you respond, these are the licensed steps, not a personal plan.

*The MHRA approved the dedicated 7.2mg single-dose Wegovy pen on 14 April 2026 for adults with BMI ≥30. Source: GOV.UK, MHRA announcement, 14 April 2026.

If you are already on Wegovy and want to understand how a mid-ladder semaglutide dose compares, the 1mg Wegovy equivalent page covers that step in detail. For the equivalent question from Mounjaro's side, our dose-conversion guide walks through the clinical considerations.

Step 3: Look at what the evidence says at maintenance, that's the relevant comparison

Because both starter doses are temporary, the clinically meaningful comparison is at maintenance. In SURMOUNT-1, tirzepatide at 15mg produced an average body-weight reduction of around 20–21% over 72 weeks among adults with obesity, as published in the New England Journal of Medicine. Semaglutide 2.4mg in the STEP 1 trial delivered around 15% average reduction over 68 weeks. The SURMOUNT-5 head-to-head trial (NEJM, 2025) confirmed tirzepatide produced greater average weight loss than semaglutide 2.4mg in a direct comparison over 72 weeks, narrowed somewhat when semaglutide is taken to the 7.2mg maintenance dose.

NICE's appraisal of tirzepatide notes these differences but does not position one medicine as universally preferable; the NICE TA1026 recommendations set eligibility criteria rather than rank the medicines. Individual response, tolerability, medical history and lifestyle factors all shape the outcome. That is precisely why the 5mg Mounjaro equivalent question (or any dose-equivalence question) is best resolved by a prescriber who has your full picture, not by a milligram comparison alone.

For a broader look at how the cost of each treatment compares over time, the tirzepatide versus semaglutide cost page sets out what to expect at different dose stages.

Step 4: Know the eligibility picture for each medicine in the UK

Both medicines carry a Black Triangle (▼) designation, meaning they are under additional MHRA monitoring. The licensed eligibility for private prescription broadly covers adults with a BMI of 30 or above, or from 27 with at least one weight-related condition such as high blood pressure, type 2 diabetes or obstructive sleep apnoea. Lower thresholds apply for some ethnic backgrounds under UK guidance.

Wegovy is not recommended for use beyond two years under NICE's TA875 framework within NHS specialist services, though private prescribing follows the SmPC and clinical judgement. Mounjaro has no equivalent two-year cap in its licence. Pregnancy, breastfeeding, and actively trying to conceive are contraindications for both; neither is licensed for under-18s. Women using oral contraceptives starting tirzepatide should add a non-oral method for the first four weeks of treatment and for four weeks after each dose increase, because the pill's absorption may be reduced, an important practical difference between the two medicines that the NHS England weight-management injections guidance sets out clearly.

Which of the two is right for you depends on your health history, your response to treatment, and a clinical assessment. Our prescribers work through that with you. Check your eligibility by starting a free consultation.