Which Is Stronger: Semaglutide or Tirzepatide?

The SURMOUNT-5 head-to-head: what the numbers show

The clearest comparison available comes from SURMOUNT-5, an open-label randomised trial published in the New England Journal of Medicine in 2025. It enrolled 751 adults living with obesity (without type 2 diabetes) and ran for 72 weeks, pitting tirzepatide directly against semaglutide 2.4 mg, the standard maintenance dose for Wegovy at the time. Tirzepatide produced a meaningfully greater reduction in average body weight across the trial period. This was the first large-scale, head-to-head comparison in people without diabetes, and its findings informed the NICE committee's discussion in technology appraisal TA1026, which recommended tirzepatide on the NHS under specific criteria.

What makes tirzepatide different mechanically is that it activates two gut-hormone receptors simultaneously: GIP and GLP-1. Semaglutide targets GLP-1 only. That dual action appears to produce a stronger appetite-suppressing signal and greater metabolic effect in the trials conducted so far, though if you want a detailed look at which is best, tirzepatide or semaglutide, the clinical picture is more nuanced than any single mechanism can explain. Neither medicine is a simple linear equation. A higher average result in a trial population does not mean everyone on tirzepatide does better than everyone on semaglutide.

It is also worth noting that semaglutide is not standing still. The MHRA approved a 7.2 mg Wegovy pen in April 2026, the highest licensed semaglutide dose in the UK. Trials at that dose reported average weight loss of around 20.7% over 72 weeks, which narrows the gap with tirzepatide 15 mg considerably. That context matters when comparing peak efficacy across the two medicines.

A factual comparison: tirzepatide vs semaglutide across key measures

The table below draws on published trial data and UK licensing. Numbers reflect average outcomes in clinical trial populations and are not predictions for any individual. All figures should be read alongside their trial conditions.

A fuller breakdown of how these medicines compare on safety grounds is covered on our semaglutide vs tirzepatide safety page, and if you want to explore the broader clinical picture, the semaglutide or tirzepatide overview is a good starting point.

Where the word 'stronger' gets complicated

Average trial outcomes are real data. They are also averages, and averages hide a lot. Some people respond remarkably well to semaglutide and less well to tirzepatide. Tolerability, existing health conditions, other medicines, how a person's body processes these drugs, and how consistently they can take them all shape what 'stronger' means in practice for a given individual. A medicine that produces a marginally lower average in a trial but suits a person's situation perfectly is the better medicine for that person.

Tolerability is a concrete example. Both medicines carry a GI-led side-effect profile. Nausea, loose stools and constipation are the most common complaints with each. If one medicine causes side effects severe enough to disrupt daily life, the titration schedule stalls and the effective dose stays lower, which affects results regardless of what the 15 mg peak suggests. This is one reason the question of which is clinically appropriate is answered at consultation, not by a league table.

There is also the oral option to consider. The Wegovy tablet, approved by the MHRA in June 2026, adds a needle-free route using semaglutide. Its trial data showed around 13.6% average weight loss over 64 weeks. Comparing that directly to injectable tirzepatide is not straightforward (different trial designs, populations and durations) but it is now part of the landscape when patients and prescribers are choosing.

For a side-by-side look specifically at Mounjaro and Wegovy as UK products, the Wegovy vs Mounjaro comparison goes into more detail on the practical differences between the two, and whether Mounjaro is stronger than Wegovy approaches the same question from a slightly different angle.

Getting the right medicine: what happens at a nume consultation

Tirzepatide, on the current evidence, produces greater average weight loss at its highest doses. That makes it the stronger medicine in the population-level sense. Whether it is the right medicine for you is a separate question. Our prescribers look at BMI, existing health conditions, any medicines you already take (including contraception and HRT, which interact differently with each), and whether you have tried either treatment before.

Both Mounjaro (tirzepatide) and Wegovy (semaglutide) are prescription-only medicines assessed individually. At nume, a named GPhC-registered Independent Prescriber reviews every consultation, not a screening algorithm. If you're switching from one to the other, there are washout considerations; our Wegovy to Mounjaro washout period page covers what the evidence says on timing.

Our clinical team makes the suitability assessment with you, not for you. That conversation starts with a free consultation, no referral, no waiting list. Start your free consultation to find out which option fits your situation.