Does semaglutide work better than tirzepatide for some people?

What does the head-to-head trial actually show?

The SURMOUNT-5 trial (published in the New England Journal of Medicine in 2025) compared tirzepatide and semaglutide 2.4mg directly in 751 adults with obesity but without type 2 diabetes over 72 weeks. Tirzepatide produced greater average weight reduction. That result now sits alongside NICE's appraisal of tirzepatide (TA1026), which noted that indirect comparisons also favour tirzepatide over semaglutide.

But a trial average is not a personal forecast. The SURMOUNT-5 distribution included participants who lost substantially more weight on semaglutide than many tirzepatide users did, and if you are curious about the specific circumstances where that pattern emerges, our page on whether Wegovy works better than Mounjaro for some people explores that question in detail. Biology is individual. Genetics, gut-hormone signalling, metabolic history and other medicines all shape the response, none of which a trial average captures.

There is also the question of dose. Wegovy's 7.2mg maintenance option, approved by the MHRA in January 2026 and available as a dedicated single-dose pen from April 2026, narrows the average gap with tirzepatide's highest doses. At 7.2mg, trials reported around 20.7% average weight loss over 72 weeks, closer to tirzepatide 15mg results than the standard 2.4mg data suggests.

The short answer: on population data, tirzepatide leads. On an individual level, semaglutide may be the better fit.

Are there clinical reasons a prescriber might favour semaglutide over tirzepatide?

Several real-world factors shift the balance. Tirzepatide is a dual GIP and GLP-1 receptor agonist, it activates two pathways simultaneously. That dual action is largely why the trial numbers favour it, and for a closer look at how those mechanisms translate to real outcomes, our page examining whether tirzepatide works better than semaglutide goes into the evidence in depth. For some patients, that single-pathway approach produces fewer gastrointestinal side effects at equivalent weight-loss outcomes, which matters practically: a medicine you tolerate is more effective than one you stop.

Contraception is another concrete example. Women taking the combined oral contraceptive pill need to add a barrier method for the first four weeks of tirzepatide and for four weeks after each dose increase, because tirzepatide's effect on gastric emptying can reduce pill absorption. NHS England's guidance on weight-management injections does not flag the same requirement for semaglutide. For someone who relies on oral contraception, that practical difference is relevant.

HRT formulation is a related consideration, NHS England advises discussing transdermal HRT with a doctor while on tirzepatide. Again, no equivalent concern applies to semaglutide. These are not reasons to avoid tirzepatide, but they are reasons the choice is genuinely clinical rather than simply statistical.

For a broader look at how the two medicines compare across several dimensions, the tirzepatide vs semaglutide overview covers the full picture.

How do the two medicines compare on the key facts?

Numbers cited from SURMOUNT-1 (NEJM) and STEP 1 (NEJM); SURMOUNT-5 published NEJM 2025.

Which medicine is right for you?

That is not a question this page (or any comparison article) can settle. A prescriber weighs your BMI, your comorbidities, your current medicines, your tolerance history and your practical circumstances. Someone who keeps their weekly pen in the fridge door alongside everyday groceries and rarely forgets a dose may prioritise efficacy data. Someone managing oral contraception, or who struggled with nausea on a previous GLP-1, may find the clinical case for semaglutide more compelling.

The Wegovy vs Mounjaro comparison looks at the same question through the lens of the brand names, and the guide to switching between the two is useful if you are already on treatment and wondering about a change. Cost is a real factor too, how Wegovy and Mounjaro compare on price runs through what private treatment typically costs by dose.

At nume, every consultation is reviewed personally by a GPhC-registered Independent Prescriber, a real clinician reads your answers, not software. You can verify our pharmacy on the GPhC register (premises number 9012878). If you would like to discuss which treatment suits your circumstances, check your eligibility and start a free consultation, there is no obligation and no upfront cost.