Is Tirzepatide Better Than Ozempic for Weight Loss?

The licence gap: why Ozempic is not the weight-loss comparison you think

Semaglutide comes in several products. Ozempic (0.5mg, 1mg, 2mg) is licensed by the MHRA for type 2 diabetes, not weight management. Wegovy (a higher-dose formulation of the same molecule) is the version licensed for weight loss in the UK. Prescribing Ozempic for weight loss is off-label, which means no formal safety-and-efficacy review for that purpose has been completed under UK licensing law. The NHS medicines page for semaglutide sets this out plainly.

Tirzepatide (Mounjaro) carries a full UK weight-management licence from the MHRA for adults with a BMI of 30 or above, or 27 or above alongside a weight-related condition such as hypertension or prediabetes. So a like-for-like comparison on weight loss really means tirzepatide versus Wegovy, not tirzepatide versus Ozempic, and if you are weighing up which of those two medicines comes out ahead, our guide to whether tirzepatide or Ozempic is better walks through the key considerations. You can read that direct comparison in detail on our tirzepatide versus Wegovy page.

If you have type 2 diabetes, Ozempic and tirzepatide (which also holds a diabetes licence) are both relevant — but that is a conversation for a diabetes specialist, not a weight-loss consultation.

What the clinical evidence actually shows

The most useful head-to-head data comes from SURMOUNT-5, a 72-week open-label trial published in the New England Journal of Medicine in 2025. It compared tirzepatide directly with semaglutide 2.4mg (Wegovy's standard maintenance dose) in 751 adults with obesity and no diabetes. Tirzepatide produced greater average weight reduction. SURMOUNT-1 (involving 2,539 participants) reported around 20–21% average body-weight loss at the 15mg dose over 72 weeks. STEP 1, the equivalent Wegovy trial, reported roughly 15% average loss at the 2.4mg maintenance dose over 68 weeks.

The gap narrows with Wegovy's newer 7.2mg dose, approved by the MHRA in January 2026, which in trials produced around 20.7% average weight loss. Tirzepatide's edge in trials is real but not enormous at the higher semaglutide doses, and individual responses vary considerably. Our fuller breakdown of tirzepatide versus Ozempic/semaglutide covers the trial figures and what they mean in practice. NICE's appraisal of tirzepatide (TA1026) also notes that indirect comparisons favour tirzepatide, while acknowledging the limitations of cross-trial data.

Side-effect profiles: broadly similar, individual variation matters

Both medicines produce a broadly similar set of side effects, driven by the GLP-1 pathway they share. Nausea, loose stools, constipation, indigestion and fatigue are the most commonly reported, particularly in the weeks after starting or after a dose increase. They tend to settle as the body adjusts. Tirzepatide adds the GIP receptor to the mix, but this does not translate into a markedly different side-effect picture in practice.

One practical difference worth knowing: for women taking oral contraceptive pills, the MHRA advises adding a non-oral method of contraception for the first four weeks of tirzepatide and for four weeks after each dose increase, because tirzepatide may reduce how well the pill is absorbed. This guidance does not currently apply to semaglutide. If that matters to your situation, it is worth discussing at consultation. You can explore the wider comparison of how these medicines sit alongside each other on our tirzepatide versus semaglutide page.

For any suspected side effect, the MHRA's Yellow Card scheme lets patients report directly, and if you experience severe, persistent stomach pain that reaches the back, seek urgent medical help given the known (though infrequent) risk of pancreatitis with GLP-1 medicines.

What IS licensed and dispensed for weight loss, and how nume prescribes it

At nume we prescribe and dispense Mounjaro (tirzepatide) and Wegovy (semaglutide) for weight management, both fully MHRA-licensed for that purpose, sourced through the authorised UK supply chain. Ozempic is not part of what we prescribe for weight loss; directing patients towards an off-label medicine would not meet our clinical standards.

If you are trying to decide between Mounjaro and Wegovy, the Wegovy versus Mounjaro comparison lays out the practical differences. A note on cost context: there is no meaningful price argument for Ozempic over its licensed equivalents, especially given it is not the appropriate product for weight management. Our cost comparison of Mounjaro and Wegovy covers what the numbers actually look like. You can also explore the full range of weight-loss treatments we offer.

Which medicine suits you is not a decision made by reading a comparison article. A real clinician (not an algorithm) reviews your consultation and makes that call with you. Our clinical team brings that prescriber judgement to every case. Place your order before 12pm on a weekday and, once approved, your treatment is dispatched the same day.