Is Tirzepatide Better Than Semaglutide for Weight Loss?

The biggest misconception: this is settled science with a clear winner

A lot of people arrive at this question already half-convinced that tirzepatide wins, full stop. The head-to-head data does lean that way, but framing it as a straightforward knockout misses something important. People respond differently to these medicines. Someone who loses 12% of their body weight on semaglutide and tolerates it well has had an excellent result, even if a trial average slightly favours the alternative. Both medicines work through overlapping but distinct mechanisms: semaglutide activates the GLP-1 receptor, while tirzepatide (sold in the UK as Mounjaro) activates both GLP-1 and GIP receptors, making it the only dual-agonist weight-loss medicine licensed here. Whether that dual action translates into a meaningfully better outcome for a specific person is precisely what a prescriber assesses, and if you want to dig into the evidence before your consultation, our page on whether tirzepatide works better than semaglutide walks through the data in detail. The trial data gives us probabilities, not predictions.

It is also worth noting that the comparison looks different depending on which semaglutide dose you are comparing against. The newer 7.2mg semaglutide maintenance dose, approved by the MHRA in January 2026, narrowed the gap considerably, trials reported around 20.7% average weight loss over 72 weeks at that dose, much closer to tirzepatide 15mg results. So the question of whether tirzepatide is better than Wegovy has become more nuanced since 2025.

Head-to-head trial data: what SURMOUNT-5 actually found

The most direct evidence comes from SURMOUNT-5, a large open-label trial published in the New England Journal of Medicine in 2025, involving 751 adults with obesity and no diabetes, followed over 72 weeks. Participants received either tirzepatide at its maximum tolerated dose or semaglutide 2.4mg weekly. Tirzepatide produced statistically greater average weight reduction. The NICE committee reviewing tirzepatide also noted, in its appraisal published in December 2024, that indirect comparisons favoured tirzepatide over semaglutide for weight loss outcomes.

Below is a factual summary drawn from clinical trial evidence and licensed indications.

A quick note on naming: Ozempic is also semaglutide, but licensed in the UK for type 2 diabetes, not weight loss. If you have seen comparisons involving Ozempic, our page on tirzepatide versus Ozempic explains the distinction clearly.

Where semaglutide still has a strong case

Trial averages do not tell the whole story. Semaglutide has a longer track record in clinical use and a broader body of evidence across different patient groups, including its STEP programme involving thousands of adults. Some people find its GI side-effect profile more manageable during the early weeks than tirzepatide's, though both medicines share a broadly similar tolerability picture. Semaglutide also holds additional UK approvals: reduction of major cardiovascular event risk in eligible adults, and, from July 2026, a conditional authorisation for a form of fatty liver disease, indications tirzepatide does not yet hold.

Then there is the practical question of cost. Wegovy has typically been priced lower than Mounjaro in the UK private market, and for some patients the difference matters when weighing a long-term treatment. That cost context is part of the clinical conversation too.

For a fuller look at how the two medicines compare across access, evidence and tolerability, our detailed tirzepatide vs semaglutide guide covers each dimension in depth. You can also read about whether Mounjaro specifically is better than semaglutide if the brand names are where you started.

Which one might suit you, and how that question gets answered

This is where the debate moves from population-level data to your situation. A prescriber considers your BMI, any weight-related conditions, your medication history, contraceptive use (tirzepatide requires an additional method for the first four weeks of treatment and after each dose increase, because it can reduce oral contraceptive absorption), your tolerance of GI side effects, and your goals. Lower BMI thresholds can apply for some ethnic backgrounds under UK guidance. None of that is captured in a trial average.

At nume, every consultation is read the same day by a named prescriber on our clinical team. They are the ones who weigh whether tirzepatide or semaglutide is the more appropriate starting point for you, or whether you meet the criteria for either. You can explore both treatment options before you start, and our frequently asked questions cover a lot of the practical detail. If you are ready to find out where you stand, check your eligibility with a free consultation and a prescriber will take it from there.