Is Mounjaro Better Than Wegovy for Weight Loss?

The biggest myth: that this comparison has a settled, universal answer

Most people searching this question expect a clear winner. The reality is more nuanced. Mounjaro (tirzepatide) and Wegovy (semaglutide) work differently at a biological level: Mounjaro activates two gut-hormone receptors (GIP and GLP-1), while Wegovy targets GLP-1 alone. That mechanistic difference has real-world consequences in trial data, but clinical trials measure population averages, not individual responses. Some people do better on one than the other for reasons that aren't fully predictable in advance.

The misconception that one is simply superior across the board leads people to request whichever scored highest in a trial, when the more useful question is which is the right fit given their specific medical picture. That is exactly what a prescriber is there to work out. If you want a deeper look at what drives the difference in mechanism and outcomes between the two medicines, our page on tirzepatide versus semaglutide covers the pharmacology alongside cost context.

What we can say with confidence is that both medicines are well-studied, both are licensed in the UK, and both are meaningfully effective for many adults with obesity or a weight-related health condition.

What the SURMOUNT-5 trial found when they went head to head

The most direct evidence comes from SURMOUNT-5, a 72-week open-label trial published in the New England Journal of Medicine in 2025, which randomised 751 adults with obesity and no diabetes to receive either tirzepatide or semaglutide 2.4mg. Tirzepatide produced a greater average reduction in body weight over the trial period. Earlier data from SURMOUNT-1 (72 weeks, 2,539 participants) had already shown average weight loss of around 20–21% at the 15mg dose. STEP 1, Wegovy's pivotal trial, reported an average of around 15% at the 2.4mg maintenance dose over 68 weeks.

The gap narrows with Wegovy's higher 7.2mg dose, approved by the MHRA in January 2026, which reached around 20.7% average weight loss over 72 weeks in trials. Whether Wegovy at 7.2mg closes the gap for a given person is something the evidence is still building on. The table below summarises the headline comparators.

Ozempic, which also contains semaglutide, is not licensed for weight loss in the UK) it is a diabetes medicine. That distinction matters when interpreting comparisons you might find elsewhere online. Our Mounjaro versus Ozempic page covers that clearly.

Side effects and tolerability: broadly similar, with some differences

Both medicines share a GI-led side-effect profile: nausea, vomiting, diarrhoea, constipation, indigestion and fatigue are the most commonly reported, particularly in the early weeks of treatment or after a dose increase. These effects are usually mild to moderate and tend to settle as the body adjusts. The NHS medicines pages for tirzepatide and semaglutide set out the full side-effect profiles for each.

Some people find one medicine better tolerated than the other, again, not in a predictable pattern that makes a blanket recommendation sensible. The MHRA's January 2026 Drug Safety Update highlighted acute pancreatitis as a known but infrequent risk with GLP-1 medicines: if you develop severe stomach pain that spreads to your back, seek urgent medical help. Both medicines carry a Black Triangle (▼) designation in the UK, meaning the MHRA actively collects safety data as clinical experience grows.

One practical point: Mounjaro uses a KwikPen delivering four weekly doses per pen; Wegovy comes as a pre-filled injection pen. Both go in the fridge. When your order arrives in its plain DPD box, the pen comes with everything you need and a Patient Information Leaflet that your prescriber will have walked you through.

Which one is right for you? That is a clinical question

Trial averages are a starting point, not a prescription. A prescriber reviewing your consultation considers your BMI, any existing conditions, medicines you already take, and your preferences, including, where relevant, the oral Wegovy tablet option approved by the MHRA in June 2026. The question of whether Wegovy or Mounjaro suits your situation becomes a concrete, answerable question in that context, rather than an abstract debate.

NICE recommends tirzepatide under TA1026 for adults with a BMI of 35 or above plus at least one weight-related comorbidity, with lower thresholds applying for some ethnic backgrounds. Semaglutide (Wegovy) is recommended under TA875, but with a maximum two-year duration and within a specialist weight management service. Private prescribing through a regulated online pharmacy operates under the licensed eligibility criteria in the product SmPCs rather than NICE's NHS-commissioning criteria, your prescriber will explain what applies to you. For more background on how the two medicines compare in practice, our Wegovy vs Mounjaro overview goes into further detail.

At nume, a real clinician reads every consultation before anything is prescribed. No algorithm makes that decision. Start your free consultation and a GPhC-registered prescriber will review whether Mounjaro, Wegovy, or another licensed option is the right fit for you.