Is Mounjaro Better Than Wegovy for Weight Loss?

Step 1: What the head-to-head trial found

The most direct comparison available is SURMOUNT-5, a 72-week open-label randomised trial involving 751 adults living with obesity but without type 2 diabetes, published in the New England Journal of Medicine in 2025. Participants were assigned either tirzepatide (the active ingredient in Mounjaro) at its maximum tolerated dose or semaglutide 2.4mg (the injection in Wegovy). Tirzepatide produced a meaningfully greater average body-weight reduction than semaglutide over the trial period. The NICE committee's appraisal of tirzepatide, published as TA1026, noted that indirect comparisons across the programme also favoured tirzepatide on average weight loss.

A few things are worth keeping in mind before reading too much into that. SURMOUNT-5 compared semaglutide at 2.4mg, the standard maintenance dose available when the trial was designed. The MHRA has since approved a higher 7.2mg Wegovy dose, including a single-dose pen, and early data for that dose report around 20.7% average weight loss at 72 weeks, which narrows the gap considerably. Trials study populations; your individual outcome will depend on factors no trial can control for.

The comparison table below pulls together the main factual markers side by side.

Step 2: How eligibility and access differ in practice

Both medicines share nearly identical private eligibility criteria under their UK licences. A BMI of 30 or above qualifies, as does a BMI from 27 upward if you have at least one weight-related condition such as high blood pressure, high cholesterol, prediabetes or obstructive sleep apnoea. Lower BMI thresholds apply for some ethnic backgrounds under UK clinical guidance. In both cases, a prescriber assesses the full picture, BMI alone is not the deciding factor.

On the NHS, the routes diverge more sharply. Wegovy is available through specialist weight management services under NICE TA875, with access largely limited to those services and waiting lists that can run long. Mounjaro is now being rolled out through GP practices under the new 2026/27 QOF arrangements, though GP participation is voluntary and eligibility criteria are strict. For anyone who does not meet those NHS thresholds or prefers not to wait, a private regulated pharmacy is the practical alternative, you can read more about how that process works on our treatment consultation page.

Cost is another practical variable. Private pricing for both medicines has shifted following Eli Lilly's list-price increase from September 2025, with Mounjaro typically ranging from around £149 to £375 per month by dose and provider. A fuller breakdown of what private weight-loss treatment costs, and what those prices do and do not include, is on our Wegovy price comparison page.

Step 3: Side-effect profiles and what they mean for your choice

Both medicines share a GI-led side-effect profile: nausea, loose stools, constipation, indigestion, and fatigue are the most commonly reported, particularly in the early weeks of treatment or after a dose increase. These effects are generally mild to moderate and tend to settle as the body adjusts. The NHS tirzepatide page and its semaglutide equivalent carry detailed lists for each.

There are a few differences worth noting clinically. Tirzepatide specifically may reduce absorption of oral medicines taken around the same time, including the contraceptive pill. Women taking oral contraceptives are advised to add a barrier method for the first four weeks of treatment and for four weeks after each dose increase. NHS England also advises discussing transdermal HRT with your doctor if you use it alongside tirzepatide. These are points a prescriber will go through with you during assessment, they are not reasons to rule out either medicine without that conversation.

The MHRA's guidance on GLP-1 medicines covers both, including a January 2026 Drug Safety Update noting acute pancreatitis as an infrequent but serious risk. Severe, persistent stomach pain that reaches the back warrants urgent medical attention regardless of which medicine you are taking.

Which one is right for you?

On average weight loss in trials, Mounjaro has produced stronger results to date. That is a factual statement, not a prescription. The gap narrows with Wegovy's newer 7.2mg dose, individual responses vary considerably, and some people tolerate one medicine better than the other. A person's existing medical conditions, other medicines, and preferences all influence which is more appropriate, and if you are weighing up whether Wegovy is better than Mounjaro for your situation, that page sets out the clinical picture in more detail.

Our prescribers discuss exactly these factors in every consultation. If you want a broader view of how the two medicines compare on other dimensions, the detail is on our Mounjaro vs Wegovy page. For a closer look at what makes one option better than the other depending on your circumstances, we cover the key variables there too. You can also read more about Wegovy specifically on our Wegovy overview, or explore the wider picture of weight loss treatment options available in the UK, including treatments that may suit people for whom Wegovy is not the right fit. Which medicine suits you is a clinical decision our prescribers make with you, not one an article can settle.