Wegovy 2.4mg Compared to Mounjaro: What the Evidence Shows

What do the trial results actually show at these doses?

The STEP 1 trial (68 weeks, adults with obesity and no diabetes) found that semaglutide 2.4mg (Wegovy) produced an average weight reduction of around 15% compared with roughly 2.4% on placebo. That figure, published in the New England Journal of Medicine, became the benchmark for GLP-1 weight-loss medicines.

Then SURMOUNT-1 arrived. Tirzepatide (Mounjaro) at 15mg produced an average reduction of around 20–21% over 72 weeks in adults with obesity and no diabetes, according to the same journal. At 10mg the figure was roughly 19%; at 5mg, around 15%. If you are curious how that 5mg tirzepatide result stacks up in more detail, our page on 0.5 Wegovy compared to Mounjaro explores the early-dose picture further. That 5mg result lands in the same territory as Wegovy 2.4mg, a detail worth noticing if tolerability is a concern.

The most direct comparison came with SURMOUNT-5: an open-label, head-to-head trial of 751 adults with obesity and no diabetes, run over 72 weeks, published in the New England Journal of Medicine in 2025. Tirzepatide produced greater average weight reduction than semaglutide 2.4mg. NICE's appraisal of tirzepatide noted indirect comparisons also favoured it. None of that makes Wegovy a poor result, 15% average weight loss from an injection is substantial. It does suggest that, on population averages, Mounjaro has the edge at directly comparable maintenance doses.

Individual response varies considerably. Some people lose more on Wegovy than the average Mounjaro participant; others plateau earlier than the numbers suggest. That is precisely why a prescriber assesses the full picture rather than handing over a pen based on a chart.

How do the two medicines differ in how they work, and does that matter at 2.4mg?

Wegovy works on a single receptor: GLP-1, a gut hormone that slows gastric emptying, curbs appetite and signals fullness to the brain. Mounjaro acts on two: GLP-1 and GIP. That dual mechanism is thought to explain a meaningful share of the additional weight loss tirzepatide produces. The NHS tirzepatide page describes this as the only dual GIP/GLP-1 receptor agonist currently licensed for weight management in the UK.

Whether the dual pathway matters specifically at the 2.4mg semaglutide level is a slightly different question. Semaglutide 2.4mg is the standard Wegovy maintenance dose, the dose that delivered the STEP 1 result. Mounjaro does not have a single fixed maintenance dose in the same way: prescribers titrate through 2.5, 5, 7.5, 10, 12.5 and 15mg depending on response and tolerance. So the comparison is less "dose vs dose" and more "one medicine's maintenance target vs another medicine's range", and our page covering 1 mg Wegovy compared to Mounjaro looks at where an earlier point in the semaglutide titration sits relative to tirzepatide's steps.

It is also worth checking whether you are looking at Wegovy or Ozempic, both contain semaglutide, but Ozempic is licensed for type 2 diabetes, not weight management. The medicines are not interchangeable for this purpose. You can read more about how doses across the two medicines relate on our Wegovy dose compared to Mounjaro page.

Are the side-effect profiles different enough to influence the choice?

Both medicines share a broadly similar side-effect profile: nausea, vomiting, diarrhoea, constipation, indigestion and fatigue are the most commonly reported, and they tend to be most noticeable after starting or after a dose increase, easing within days to a couple of weeks for most people. That pattern holds for both GLP-1 and dual GIP/GLP-1 medicines. The NHS semaglutide page sets out the full list for Wegovy, and the equivalent NHS tirzepatide page does the same for Mounjaro.

There are practical differences a prescriber weighs. Tirzepatide has a specific interaction with oral contraceptive pills: for the first four weeks of treatment and for four weeks after each dose increase, an additional non-oral method of contraception (such as condoms) is recommended, because absorption of the pill may be reduced. There is no equivalent evidence of that interaction for semaglutide. If you take oral contraception, that is a relevant conversation to have at consultation, not a reason to avoid Mounjaro, but a reason to plan.

For a broader look at how tolerability compares across the two medicines generally, the Wegovy vs Mounjaro page goes into more depth. Both carry a Black Triangle (▼) status from the MHRA, meaning they are subject to additional monitoring while post-market safety data accumulates.

How do Wegovy 2.4mg and Mounjaro compare on cost and NHS availability?

Cost is a real factor for most people weighing these options. Eli Lilly raised Mounjaro's UK list price substantially from 1 September 2025, typical private prices now range roughly £149–£375 per month by dose and provider, as widely reported. That makes dose-level cost meaningful: lower Mounjaro doses cost less per pen, which partly explains why the comparison between Wegovy 2.4mg and Mounjaro's mid-range doses is so frequently asked, and our page on 1mg Wegovy compared to Mounjaro unpacks how costs and outcomes shift at that earlier semaglutide dose. There is a fuller discussion of the pricing picture on our page on why Wegovy tends to cost less than Mounjaro.

On the NHS, tirzepatide (NICE TA1026, December 2024) and semaglutide/Wegovy (NICE TA875) are both recommended, but criteria and access routes differ. Tirzepatide is available through a phased rollout based on BMI and the number of weight-related conditions; Wegovy is available through specialist weight management services, with a maximum treatment duration of two years under TA875. Waiting lists for both NHS routes can be long.

Private treatment through a regulated pharmacy is the route for people who do not yet meet NHS criteria or do not want to wait. Our free consultation is the starting point: a prescriber reviews your medical history, weight, and circumstances, and discusses which medicine is clinically appropriate for you. No medicine is recommended before that conversation.

Which of these medicines suits you is a clinical decision our prescribers make with you, based on your health history, what you have tried before, and what matters most to you in a treatment. Check your eligibility to start that conversation.