Mounjaro®
Starting from £179.99/mo
Start journey Learn moreHow Ozempic, Wegovy and Mounjaro compare — and what a switch really involves
The licensing difference that changes everything
The most important thing to understand before asking about switching is that Ozempic and Mounjaro are not direct equivalents. Ozempic contains semaglutide at doses up to 2mg and is licensed solely for type 2 diabetes in the UK, as the MHRA makes clear. It has never held a UK weight-management licence. Wegovy is also semaglutide, but at a 2.4mg maintenance dose (now up to 7.2mg following MHRA approval in January 2026), specifically licensed for weight management in adults with a BMI of 30 or above, or 27 or above with a weight-related health condition.
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, the only medicine of its kind licensed for weight loss in the UK. It works on two gut-hormone pathways rather than one. If you have been taking Ozempic for weight management, the clinically appropriate comparison is usually semaglutide versus tirzepatide, using the licensed weight-management form of semaglutide (Wegovy) as the benchmark. That distinction matters when your prescriber is weighing up a switch.
Under NICE appraisal TA1026, tirzepatide is recommended for NHS use in adults with a BMI of 35 or above and at least one weight-related comorbidity (with lower thresholds for some ethnic backgrounds). Wegovy carries its own NICE recommendation under TA875. Neither recommendation applies to Ozempic in a weight-loss context.
What the trial data shows about Mounjaro versus semaglutide for weight loss
The SURMOUNT-5 trial, published in the New England Journal of Medicine in 2025, compared tirzepatide directly against semaglutide 2.4mg over 72 weeks in adults with obesity and no diabetes. Tirzepatide produced greater average weight reduction. In the earlier SURMOUNT-1 trial (2,539 participants), tirzepatide 15mg led to an average body-weight reduction of around 20–21% over 72 weeks. The STEP 1 trial of semaglutide 2.4mg, also published in the NEJM, reported approximately 15% average weight loss over 68 weeks.
The table below summarises the key factual differences. Numbers from clinical trials are averages; individual results vary, and no medicine guarantees a specific outcome for any one person.
| Factor | Ozempic (semaglutide) | Wegovy (semaglutide) | Mounjaro (tirzepatide) |
|---|---|---|---|
| UK licence | Type 2 diabetes only | Weight management | Weight management & type 2 diabetes |
| Mechanism | GLP-1 receptor agonist | GLP-1 receptor agonist | Dual GIP + GLP-1 receptor agonist |
| Maintenance dose range | Up to 2mg weekly | Up to 7.2mg weekly (MHRA-approved, 2026) | Up to 15mg weekly |
| Average weight loss in trials | Not studied for weight loss at this dose | ~15% (STEP 1, 68 weeks) [NEJM] | ~20–21% at 15mg (SURMOUNT-1, 72 weeks) [NEJM] |
| NICE recommendation for weight loss | No | Yes (TA875) | Yes (TA1026) |
| Dispensed by nume for weight management | No | Yes | Yes |
How a switch is handled in practice
There is no single universal protocol for moving between these medicines, and timing matters. A prescriber will typically consider which dose of Ozempic you have been taking, how long you have been on it, how well your body has tolerated it, and what your weight-management goals are. The overlap between semaglutide and tirzepatide at the receptor level means switching is not a simple one-for-one substitution, dose equivalence does not translate cleanly between the two.
A practical habit worth building before your consultation: check the date on your last Ozempic injection and note it down. Knowing exactly when you last dosed helps a prescriber calculate the safest timing for any change. That single piece of information takes under a minute to confirm and can meaningfully shape the clinical conversation. For more on the mechanics of how a switch from Ozempic to Mounjaro is structured, our detailed guide walks through the key steps.
People also ask about going in the other direction. If you are already on tirzepatide and wondering whether switching back to Ozempic is sensible, the same principle applies, and in most weight-management contexts, Wegovy rather than Ozempic would be the clinically logical comparator. You can also read about switching from Mounjaro to semaglutide more broadly if Wegovy is your intended destination.
Which medicine is right for you, and how to find out
nume prescribes Mounjaro and Wegovy for weight management; we do not prescribe Ozempic for this purpose because it does not hold that UK licence. If you are currently taking Ozempic off-label for weight loss and want to move onto a licensed pathway (whether that is tirzepatide, Wegovy, or a switch between the two) the right first step is a clinical consultation. You can also compare Wegovy and Mounjaro side by side or look at the cost difference between them before you decide.
Which medicine suits you is a clinical decision our prescribers make with you, based on your health history, your current medication, your goals and how your body has responded to treatment so far. Our clinical team, led by a GPhC-registered Independent Prescriber, reviews every consultation personally. A real clinician reads your answers, not software. Check your eligibility and start your free consultation today.
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