Mounjaro®
Starting from £179.99/mo
Start journey Learn moreThe practical and clinical factors behind a Saxenda-to-Mounjaro switch
Why people are looking to switch in the first place
Saxenda's manufacturer, Novo Nordisk, announced a UK market withdrawal in early 2024. Existing users have had to think about next steps, and tirzepatide has become the most discussed alternative. That makes sense at a headline level: both are injectable weight-management medicines taken alongside a reduced-calorie diet, and both slow gastric emptying. But liraglutide (Saxenda) activates only the GLP-1 receptor, while tirzepatide activates both GLP-1 and GIP receptors. That dual action is why the SURMOUNT-1 trial reported average weight reductions of around 20–21% at the highest dose over 72 weeks, versus the approximately 6–7% seen with Saxenda in its own pivotal trials. The two medicines are in different classes.
The practical question, then, is not simply which is stronger. It is whether Mounjaro is clinically appropriate for you, what happens to your current dose of liraglutide during the changeover, and how quickly you can realistically start. A full comparison of both medicines side by side is set out in our Saxenda vs Mounjaro guide, which covers mechanism, eligibility and the trial evidence in more detail.
What the evidence says when you set both medicines alongside each other
Numbers are useful here, so the table below brings the main facts together. All figures are from published clinical trials and UK regulatory sources.
| Factor | Saxenda (liraglutide) | Mounjaro (tirzepatide) |
|---|---|---|
| Mechanism | GLP-1 receptor agonist | Dual GIP and GLP-1 receptor agonist |
| Injection frequency | Once daily | Once weekly |
| Average weight loss (pivotal trial) | ~6–7% body weight (SCALE trial) | ~20–21% body weight at 15mg (SURMOUNT-1, NEJM) |
| UK licence for weight management | Withdrawn from UK market (2024) | Yes (BMI ≥30, or ≥27 with a weight-related condition |
| Dispensed by nume for weight loss | No | Yes |
Saxenda is no longer available in the UK, so this is not a choice between two active options) it is a question of whether tirzepatide is the right next step for you specifically. The eligibility criteria for Mounjaro cover BMI, any weight-related health conditions, medicines you take and your medical history. A prescriber weighs all of that, not just your current treatment. The SURMOUNT-5 head-to-head trial (published in the New England Journal of Medicine in 2025) also showed tirzepatide producing greater average weight reduction than semaglutide 2.4mg, the next most commonly considered alternative, which adds context to the switching conversation.
How a switch actually works, the practical steps
There is no universal protocol for crossing from liraglutide to tirzepatide, and the details of how the switch is managed depend on factors your prescriber will review: how long you have been on Saxenda, whether you are still taking it, your current dose and any side effects you experienced. In most cases there is no required washout period before starting tirzepatide, but the starting dose is always 2.5mg regardless of what you were on before. That first pen is a tolerability step; it exists to let your system adjust to a new mechanism, not to produce immediate weight change.
Timing matters practically too. If Saxenda has run out and you are waiting until the end of the month before ordering, it may be worth knowing that orders placed at our consultation page before 12pm any weekday are dispatched the same day, so there is no need to stretch the gap further than your clinical review requires.
Evidence checks are part of the process for patients transferring from another medicine. At nume, a prescriber reviews your clinical picture on the same day you apply. There is no algorithm making the call. Our clinical team looks at your full history before any prescription is issued.
What is licensed for weight loss in the UK now, and what comes next
Because Saxenda has been withdrawn and Ozempic is licensed only for type 2 diabetes, the injectable weight-management medicines currently licensed in the UK are tirzepatide (Mounjaro) and semaglutide (Wegovy). For people exploring what else might be available further down the line, retatrutide is the most discussed pipeline medicine; our retatrutide vs Mounjaro comparison covers what the early trial data shows and why it is not yet a clinical option. There is also a growing conversation about switching from one licensed medicine to another once NICE guidance evolves, covered in our piece on what switching from tirzepatide might eventually look like.
Right now, Mounjaro is the most clinically supported option for people moving away from liraglutide. Which suits you depends on your health picture. That is a decision our prescribers make with you, not for you, after a proper review.
Looking to start your weight loss journey?
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