Mounjaro®
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Start journey Learn moreOzempic, Mounjaro, and weight loss: what the UK licences actually say
You're on Mounjaro for weight loss (why Ozempic isn't the straight swap it sounds like
Picture the situation: you've been using Mounjaro for weight management, something has changed) maybe supply, maybe cost, maybe a prescriber has mentioned alternatives, and you're researching whether Ozempic covers the same ground. It's a reasonable question. Both drugs involve GLP-1 receptor pathways, both are injected weekly, and in everyday conversation people often treat them as interchangeable.
They are not interchangeable. Mounjaro (tirzepatide, made by Eli Lilly) is a dual GIP and GLP-1 receptor agonist with a UK marketing authorisation for weight management in adults with a BMI of 30 or above, or 27 or above alongside a weight-related health condition. Ozempic is semaglutide, made by Novo Nordisk, and its UK licence covers type 2 diabetes, not weight loss. The MHRA is explicit on this point: the government's GLP-1 guidance for patients sets out clearly which medicines are and are not licensed for weight management.
A prescriber cannot legitimately write Ozempic for weight loss in private practice; it would be off-label prescribing in a context where an on-label alternative exists. That matters both clinically and from a regulatory standpoint. If someone has offered you Ozempic for weight loss without acknowledging this, that is worth raising with them.
The medicine that fills the Ozempic-shaped gap in weight management
The semaglutide product licensed for weight loss in the UK is Wegovy, not Ozempic. Same active ingredient, different dose, different licence. Wegovy's top maintenance dose is 2.4mg weekly (with a 7.2mg option now available following MHRA approval in 2026); Ozempic tops out at 1mg for most diabetes indications. The dosing architectures reflect the different clinical purposes.
So if you are currently on Mounjaro and want to understand whether semaglutide-based treatment could work for you, the relevant comparison is Mounjaro to Wegovy, not Mounjaro to Ozempic. That page works through dose equivalences and the clinical considerations involved in that specific switch. Wegovy is dispensed by nume's GPhC-registered pharmacy through a private prescription; NICE's appraisal of semaglutide for weight management (TA875) confirms its place in the evidence base, and the NHS medicines page for semaglutide covers how it works and what to expect.
The short version: the switch you may actually be looking for (from a dual-agonist to a GLP-1 agonist for weight loss) exists, and it involves Wegovy, not Ozempic.
How Mounjaro and Ozempic compare on the numbers (and why the trial context matters)
| Factor | Mounjaro (tirzepatide) | Ozempic (semaglutide) |
|---|---|---|
| UK licence | Weight management + type 2 diabetes | Type 2 diabetes only |
| Mechanism | Dual GIP and GLP-1 receptor agonist | GLP-1 receptor agonist |
| Injection frequency | Once weekly | Once weekly |
| Average weight reduction in trials | ~20–21% at 15mg over 72 weeks (SURMOUNT-1, NEJM) | Not trialled primarily for weight loss at Ozempic doses; Wegovy 2.4mg showed ~15% over 68 weeks (STEP 1, NEJM) |
| Dispensed by nume for weight loss | Yes | No |
The trial figures in that table carry an important caveat: the Ozempic dose used in diabetes trials is lower than the Wegovy dose used in weight-loss trials. Comparing Mounjaro's weight results directly against Ozempic's diabetes-indication results is not a fair read of the evidence. A fuller evidence comparison of Ozempic and Mounjaro goes into this in more detail. For the head-to-head between the two weight-loss-licensed medicines, the Wegovy vs Mounjaro comparison is the right place to start.
If you're considering a switch, here's what happens at consultation
Any change to a GLP-1 treatment (medicine, dose, or frequency) goes through clinical review. At nume, that means a named prescriber reads your answers, checks your current dose, reviews your history, and decides whether a different treatment is appropriate. It is not a tick-box process. If you're already on Mounjaro and exploring whether Wegovy might suit you better, our guidance on converting from Mounjaro to Wegovy is worth reading before your consultation, alongside the conversion chart between the two, which gives a practical reference point for what a prescriber might consider.
Transfer patients and people requesting dose changes provide supporting evidence so our prescribers can make the call safely. The same-day clinical review applies: order before 12pm on a working day, and if your prescription is approved, it goes out the same afternoon. Your pen arrives the next working day in a plain DPD parcel, no branding, no indication of what's inside, tracked to your door.
Ozempic for weight loss is not something our prescribers can prescribe, because it is not licensed for that purpose in the UK. If weight management is the goal, the conversation is about Mounjaro or Wegovy. Our free consultation is where that conversation starts. You can also read more about how the two licensed treatments compare before you do.
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