Is Tirzepatide Better Than Wegovy? What the Trial Data Actually Shows

What SURMOUNT-5 and the wider trial record actually found

For years, comparisons between tirzepatide and semaglutide rested on indirect analysis, stacking results from separate trials that used different designs and different populations. That changed with SURMOUNT-5, a 72-week, randomised, open-label trial published in the New England Journal of Medicine in 2025, which put the two medicines head-to-head directly in 751 adults with obesity and no diabetes. Tirzepatide produced a greater average reduction in body weight than semaglutide 2.4 mg over that period. A fuller breakdown of those result figures shows the gap was meaningful, though not universal, some participants did better on semaglutide.

NICE took note. Its appraisal of tirzepatide (NICE technology appraisal TA1026) acknowledges that indirect comparisons favour tirzepatide, and SURMOUNT-5 now adds a direct data point. The earlier SURMOUNT-1 trial, which recruited 2,539 adults with obesity, recorded around 20 to 21 per cent average weight loss at the 15 mg dose over 72 weeks. The STEP 1 trial for semaglutide 2.4 mg reported roughly 15 per cent over 68 weeks, published in the New England Journal of Medicine. One important caveat: trial populations, protocols and follow-up lengths differ, so headline percentages should not be read as a simple scoreboard.

Semaglutide has not stood still. The MHRA approved a 7.2 mg maintenance dose of Wegovy in 2026, including a dedicated single-dose pen, and trials at that higher dose reported around 20.7 per cent average loss, a figure that narrows the gap with tirzepatide's top dose considerably. If you want to explore whether tirzepatide is better than Ozempic, that page covers semaglutide in its earlier licensed forms and how the evidence stacks up there too. The comparison that was settled last year may look different again as 7.2 mg data matures.

The mechanism difference and what it means in practice

Tirzepatide is a dual GIP and GLP-1 receptor agonist, it activates two gut-hormone pathways involved in appetite regulation and blood-sugar control. Wegovy acts on GLP-1 receptors alone. That biological distinction is one reason researchers expected tirzepatide to outperform on average weight outcomes, and the SURMOUNT-5 results are consistent with that hypothesis.

In everyday terms, both medicines slow gastric emptying and reduce appetite. People taking either one typically feel fuller sooner and find it easier to eat less without consciously restricting. The practical difference most patients notice is a matter of degree rather than kind, though side-effect profiles and individual tolerability vary. A side-by-side look at tirzepatide and Wegovy goes further into how those lived experiences differ, and if you are specifically trying to work out whether Mounjaro is better than Wegovy for your situation, that page addresses the question in more depth.

For people who have already tried one and found it well-tolerated but limited in effect, switching to the other is a conversation worth having with a prescriber. That is not a decision to make based on a forum post, it needs a clinical review of your current dose, your progress and your overall health.

Licensed eligibility: where the two medicines align and where they diverge

Both medicines share the same core private eligibility threshold: adults with a BMI of 30 or above, or 27 to 29.9 alongside at least one weight-related health condition such as high blood pressure, type 2 diabetes or high cholesterol. Lower BMI thresholds apply for some ethnic backgrounds under UK clinical guidance. A prescriber looks at the whole picture, not just the number on a BMI chart.

On the NHS the routes differ. NICE's recommendation for tirzepatide (TA1026) covers adults with a BMI of 35 or above plus at least one weight-related comorbidity, through a phased rollout tied to GP commissioning. NICE's recommendation for semaglutide (TA875) is narrower: it specifies use for a maximum of two years, within specialist weight management services with multidisciplinary support. Waiting lists for those services can be long. For people who do not meet current NHS criteria or prefer not to wait, a private prescription route through a regulated UK pharmacy is the practical alternative, you can find out more about the process on the treatment overview page.

The table below sets out the key factual differences between the two medicines.

Which one is right for you, and why that is a clinical question

Trial averages describe populations. Your prescriber is interested in you: your weight history, your existing conditions, the medicines you already take, how your gut tolerates GLP-1-type treatment, and what you are hoping to achieve. Someone who has tried semaglutide and lost meaningful weight without troublesome side effects may have no reason to switch. Someone who struggled with tolerability on one might find the other suits them better. Neither of those conclusions can be drawn from a comparison article.

Cost is part of the picture too, a detailed price comparison between Mounjaro and Wegovy covers what each typically costs privately and what those figures include. And if you are weighing tirzepatide against semaglutide in the broader sense (not just the injectable form) our prescribers cover that comparison separately.

At nume, our prescribers review every consultation personally, the same day it arrives, before anything is dispensed. If you want a clinical view on which medicine fits your situation, the right starting point is a conversation. Speak to our prescribers through a free consultation and get an answer based on your health, not a headline.