Mounjaro®
Starting from £179.99/mo
Start journey Learn moreThe factors that actually drive this decision
The mechanism difference, and why it matters for your response
Mounjaro (tirzepatide, made by Eli Lilly) activates two gut-hormone receptors simultaneously: GIP and GLP-1. Wegovy (semaglutide, made by Novo Nordisk) targets GLP-1 alone. That isn't a reason to call one superior, but it is a real biological distinction that can explain why some patients respond better to one than the other.
In the SURMOUNT-5 head-to-head trial (751 adults with obesity, run over 72 weeks) tirzepatide produced a greater average weight reduction than semaglutide 2.4mg. NICE's appraisal of tirzepatide (TA1026) notes that indirect comparisons from the evidence also favour tirzepatide. That is the current picture for most maintenance doses.
The gap is narrowing, though. Wegovy's newer 7.2mg dose (approved as a dedicated single-dose pen by the MHRA on 14 April 2026) delivered around 20.7% average weight loss over 72 weeks in trials, closing toward tirzepatide 15mg territory. So if someone tells you Wegovy is simply the weaker option, that framing is already out of date.
There is one common misconception worth gently setting aside: that switching medicines always means starting from scratch with side effects. Tolerability profiles for both are similar (largely gastrointestinal), and many patients switching between them don't find one dramatically harder to tolerate. What varies is individual response, not a universal rule.
If you want a fuller side-by-side, the Wegovy vs Mounjaro comparison page goes through both profiles in detail.
What might make a prescriber recommend switching to Wegovy from Mounjaro
A prescriber might consider moving you toward Wegovy if you are not responding as expected to tirzepatide, if there is a clinical reason to favour GLP-1 mono-agonism, or if supply or personal circumstances (the upcoming 7.2mg pen's no-refrigeration-free storage still requires a cold chain, but the oral Wegovy tablet does not, for patients where injection remains unsuitable) make a change practical.
The question of switching the other way (from Wegovy to Mounjaro) tends to come up when someone has had limited response on semaglutide and wants to explore the dual-agonist route. The semaglutide to tirzepatide switch page covers that direction more specifically.
Cost context is also a real-world factor for many patients. Private prices for both medicines vary by dose and provider. The price difference between Mounjaro and Wegovy is examined separately, the short version is that neither is cheap at the higher maintenance doses, and a clinically unsuitable switch made purely on price is rarely a good trade.
Your prescriber will look at your current dose, your weight-loss progress to date, any side effects you've reported, and your medical history before recommending any change. That clinical picture is what drives the decision, not the brand name.
Comparing the two medicines: a factual summary
| Factor | Mounjaro (tirzepatide) | Wegovy injection (semaglutide) |
|---|---|---|
| Receptor target | Dual GIP + GLP-1 agonist | GLP-1 agonist |
| UK licence (weight management) | BMI ≥30, or ≥27 with a weight-related condition | BMI ≥30, or ≥27 with a weight-related condition |
| Trial weight loss (average, highest licensed dose) | ~20–21% at 15mg over 72 weeks [SURMOUNT-1, NEJM] | ~15% at 2.4mg over 68 weeks; ~20.7% at 7.2mg [STEP 1, NEJM; MHRA 2026] |
| Highest licensed dose | 15mg weekly | 7.2mg weekly (single-dose pen approved April 2026) |
| NICE recommendation | TA1026 (December 2024, updated September 2025) | TA875 (March 2023, specialist services, max 2 years) |
| Injection frequency | Once weekly | Once weekly |
Numbers in this table are from the SURMOUNT-1 trial published in the New England Journal of Medicine and NICE TA1026's recommendations chapter. Clinical results vary between individuals, trial averages are not guarantees.
How to have this conversation with your prescriber
The most productive switch conversations start with specifics: how much weight have you lost, at what dose, over how long, and what side effects (if any) have you had? A prescriber can only advise meaningfully with those details in front of them.
At nume, every repeat and every change request is clinically re-reviewed. A real prescriber reads your answers; the consultation doesn't run on autopilot. If you are already a patient considering a switch, our support team can guide you to the right next step, and our dedicated page on how to switch from Mounjaro to Wegovy walks through what that process typically involves. If you are new and weighing up which medicine to start, the Mounjaro or Wegovy page approaches that starting-point question differently.
Which medicine suits your situation is a clinical decision our prescribers make with you, not one a comparison table can settle, and if you'd like to evaluate Novo Nordisk as the company behind Wegovy alongside Eli Lilly's Mounjaro before that conversation, that background is available too. Check your eligibility and start your free consultation to get that conversation going.
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