Tirzepatide vs liraglutide: what does the evidence actually show?

Do tirzepatide and liraglutide actually work differently, or is the distinction just marketing?

The difference is pharmacological, not cosmetic. Liraglutide mimics one gut hormone (GLP-1) slowing gastric emptying, reducing appetite and nudging blood-sugar regulation via a single receptor pathway. Tirzepatide activates two receptors simultaneously: GLP-1 and GIP. GIP (glucose-dependent insulinotropic polypeptide) plays a separate role in energy balance, and combining both signals appears to amplify the appetite-suppressing effect beyond what either achieves alone. The NHS medicines page for tirzepatide describes it as the only licensed dual-agonist in its class, and the NICE technology appraisal TA1026 notes this dual mechanism when setting out the clinical case.

In practical terms, both medicines are once-daily or once-weekly subcutaneous injections, liraglutide requires a daily injection at its Saxenda dose, tirzepatide a once-weekly pen. That frequency difference matters to many people, and it came up repeatedly in our prescribers' conversations long before the trial data was published.

Neither medicine is a substitute for the other. They sit in the same therapeutic neighbourhood but are not interchangeable, and switching between them requires a prescriber's assessment rather than a simple swap.

What do the trial results for liraglutide vs tirzepatide actually show?

The SURMOUNT-1 trial, published in the New England Journal of Medicine, followed 2,539 adults with obesity over 72 weeks. Those on tirzepatide 15mg lost an average of around 20–21% of body weight. That is a substantial figure by any clinical measure. The liraglutide SCALE Obesity trial, also in the NEJM, reported average weight loss of around 5–8% over 56 weeks at the 3mg Saxenda dose. The studies used different designs, populations and durations, so direct comparison has limits, but NICE's own analysis in TA1026 acknowledged that indirect comparisons favour tirzepatide over older GLP-1 agents including liraglutide.

The gap in average results does not tell the whole story. Some people respond well to liraglutide; some experience side effects on tirzepatide that change the clinical picture. Individual response, tolerability and medical history all shape what a prescriber would recommend, and our page on whether liraglutide is better than tirzepatide works through those nuances in more detail. Trial averages are a starting point, not a prediction.

If you are considering moving between these treatments, the page on switching from liraglutide to tirzepatide covers what that process involves clinically.

Is liraglutide still prescribed for weight loss in the UK, and who would be offered it?

Liraglutide (Saxenda) holds a UK licence for weight management and can be prescribed privately. It is not available from nume; our prescribers work with tirzepatide (Mounjaro) and semaglutide (Wegovy) for weight loss. If you have been offered liraglutide elsewhere and want to understand your options, the weight-loss treatment overview sets out what is licensed and dispensed through our pharmacy.

Liraglutide at a lower dose is also the active ingredient in Victoza, which is licensed for type 2 diabetes. These are separate products at different doses, Saxenda (3mg for weight management) and Victoza (up to 1.8mg for diabetes) are not the same thing and should not be treated as interchangeable.

For people who do not meet the criteria for one medicine or who find a particular side-effect profile difficult, the choice between available treatments is genuinely clinical. A prescriber looks at your full history, not just your BMI, and our liraglutide vs Mounjaro comparison explains how the two treatments differ across the factors that typically shape that decision. The difference between liraglutide and tirzepatide page goes into more depth on how that assessment tends to play out.

Which weight-loss medicines does nume actually dispense, and how does the process work?

nume dispenses tirzepatide (Mounjaro) and semaglutide (Wegovy) for weight management, both are licensed in the UK for adults with a BMI of 30 or above, or 27 or above with at least one weight-related condition such as high blood pressure, high cholesterol or type 2 diabetes. Lower thresholds apply for some ethnic backgrounds under UK guidance. Liraglutide is not part of our formulary.

Every consultation at our GPhC-registered pharmacy is personally reviewed by a GPhC-registered Independent Prescriber, a real clinician reads your answers. Order by midday Monday to Friday and, once clinically approved, treatment is dispatched the same day and delivered free by DPD the next working day. (If you are planning around a payday or a Monday after a bank holiday, it is worth bearing the cut-off in mind.) Plain packaging, tracked, no hidden fees.

For a full picture of Mounjaro specifically, the Mounjaro treatment page covers mechanism, eligibility and what to expect. If cost is a consideration, the page on Mounjaro pricing in the UK explains what a legitimate private price includes and why very low prices are a warning sign rather than a bargain.

Which of the licensed medicines suits you is a clinical decision our prescribers make with you, not a call you need to make from a comparison table. Start your free consultation and a prescriber will assess your full picture.