Is Ozempic or Mounjaro Better for Weight Loss in the UK?

You searched for Ozempic vs Mounjaro — here is the licencing reality you need first

Imagine you have just spent twenty minutes searching and every result seems to assume you already know which is which. You do not want a biology lecture; you want a straight answer. So here it is: in the UK, Ozempic is not licensed for weight loss. It is licensed for type 2 diabetes. Its close relative Wegovy contains the same active ingredient, semaglutide, but is the formulation approved by the MHRA for weight management. Mounjaro (tirzepatide), made by Eli Lilly, is also licensed for weight management in adults with a BMI of 30 or above, or 27 or above with at least one weight-related health condition. The NHS medicines page for tirzepatide explains this clearly.

So the real question most people are trying to answer is: what is better, Mounjaro or Wegovy? That is a fair and useful question, and one with clinical trial data to support a proper answer.

A quick check worth doing right now: if a seller is offering you Ozempic described as a weight-loss medicine, that is a red flag. The MHRA has warned repeatedly about medicines sold online without a prescription in misleading contexts. Spending sixty seconds verifying any online pharmacy on the GPhC pharmacy register before handing over payment is the fastest way to protect yourself.

Mounjaro vs Wegovy: what the trial results show

Both Mounjaro and Wegovy reduce body weight substantially in clinical trials, but the numbers point in the same direction consistently. In the SURMOUNT-1 trial, participants taking tirzepatide at the highest dose lost an average of around 20–21% of their body weight over 72 weeks. In the STEP 1 trial, semaglutide 2.4mg produced an average reduction of approximately 15% over 68 weeks. The SURMOUNT-1 results published in the New England Journal of Medicine and the STEP 1 paper are both publicly available if you want to read the primary data.

The most direct comparison came from the SURMOUNT-5 head-to-head trial, published in the New England Journal of Medicine in 2025, which ran for 72 weeks in adults with obesity and no diabetes. Tirzepatide produced greater average weight reduction than semaglutide 2.4mg. NICE's appraisal of tirzepatide (TA1026) also notes that indirect comparisons favour tirzepatide. It is worth knowing that a newer, higher-dose 7.2mg Wegovy pen was approved by the MHRA in April 2026, with trial data showing around 20.7% average weight loss, narrowing the gap with tirzepatide's top dose considerably. The picture is still developing.

Neither medicine is described usefully as a winner in isolation. Results depend on starting weight, dose reached, how long treatment continues, side-effect tolerance, and the lifestyle support alongside it.

Side-effect profiles and practical differences between the two

Both medicines share a gastrointestinal side-effect profile: nausea, loose stools, constipation, reflux and reduced appetite are the most common complaints. These tend to be most noticeable in the early weeks or after a dose step-up, and they often settle as the body adjusts. You can read the full NHS-level side-effect information for tirzepatide and for semaglutide directly.

Mounjaro works on two receptors simultaneously (GIP and GLP-1) making it the only dual-agonist weight-loss medicine currently licensed in the UK. Wegovy acts on the GLP-1 receptor alone. Whether that mechanistic difference translates into a meaningfully better experience for a given person is something a prescriber works through with you individually, taking into account your health history, any other medicines you take, and your personal preferences.

One practical note worth raising with a prescriber: women using oral contraceptives starting Mounjaro should use an additional non-oral method for the first four weeks of treatment and for four weeks after each dose increase, because absorption of the pill may be reduced. NHS guidance notes no equivalent evidence of this effect with semaglutide. It is a small logistical difference that is easy to miss.

For a broader look at how these two medicines sit against each other on the key criteria, the table below pulls the facts together.

What is licensed for weight loss in the UK, and how to access it

To be clear about what you can actually be prescribed: the two injectable weight-loss medicines currently licensed in the UK are Mounjaro and Wegovy. Ozempic is not one of them, regardless of what circulates online. If you want to explore the differences between Mounjaro and Ozempic in more depth, or understand why tirzepatide tends to produce stronger results than semaglutide in head-to-head data, those questions are answered separately.

For people weighing up the two licensed options, the comparison between Wegovy and Mounjaro covers the clinical picture in more detail, including eligibility thresholds and how NICE has appraised each one. If you are still working out which is better, Ozempic or Mounjaro, that page walks through the key differences between the two semaglutide options and tirzepatide, including the licensing distinction that matters most. For anyone who wants a closer look at what is better, Ozempic or Mounjaro, covering the practical and clinical considerations side by side, that page goes into further detail. The cost angle has its own page too: how Wegovy compares to Mounjaro on price explains what private treatment typically costs and what that price should include.

At nume, our prescribers review every consultation personally. Which of these medicines suits you is not a decision made by an algorithm or a comparison table. It is a clinical one, shaped by your full health picture. If you are ready to start that conversation, start your free consultation and a GPhC-registered prescriber will review your answers the same day.