Mounjaro®
Starting from £179.99/mo
Start journey Learn moreWhy hunger changes after a Mounjaro-to-Wegovy switch, and what to do about it
Step 1: Understand what changed in your body when the medicine changed
Mounjaro (tirzepatide) is the only dual GIP and GLP-1 receptor agonist licensed for weight management in the UK. Wegovy (semaglutide) targets the GLP-1 receptor only. The GIP component in tirzepatide appears to add an extra layer of appetite suppression beyond what GLP-1 activation alone produces, which is one reason the SURMOUNT-1 trial, published in the New England Journal of Medicine, reported average weight reductions of around 20–21% at the highest tirzepatide dose over 72 weeks, compared to roughly 15% at Wegovy's 2.4mg maintenance dose in the STEP 1 trial.
When you switch from Mounjaro to Wegovy, that second receptor pathway goes quiet. For many people this passes as the new medicine establishes itself and the dose climbs toward maintenance. For others, hunger stays more noticeable, particularly if they moved to a lower-than-equivalent Wegovy dose at the point of switching. The practical steps involved in switching matter enormously here: the timing gap between your last Mounjaro pen and your first Wegovy dose, and what starting dose you've been placed on, both shape how your appetite responds in those first weeks.
It's also worth noting that weight-loss medicines of this class slow gastric emptying, so hunger tends to be most suppressed after a dose increase and can ease slightly between increases. If you've just moved to the lowest Wegovy starting dose, you may simply be earlier in the titration ladder than you were on Mounjaro.
Step 2: Compare the two medicines side by side
The table below sets out the verified facts on each medicine to help you have a productive conversation with your prescriber. Neither column declares a winner, the right choice depends on clinical factors specific to you.
| Feature | Mounjaro (tirzepatide) | Wegovy (semaglutide) |
|---|---|---|
| Mechanism | Dual GIP + GLP-1 receptor agonist | GLP-1 receptor agonist |
| Average weight loss (clinical trials) | ~20–21% at 15mg over 72 weeks (SURMOUNT-1, NEJM) | ~15% at 2.4mg over 68 weeks (STEP 1, NEJM); ~20.7% reported at 7.2mg over 72 weeks |
| UK dose range | 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg | 0.25mg → 0.5mg → 1.0mg → 1.7mg → 2.4mg (→ 7.2mg maximum) |
| UK licence for weight management | Yes (BMI ≥30, or ≥27 with a weight-related condition | Yes) BMI ≥30, or ≥27 with a weight-related condition |
| MHRA monitoring status | Black Triangle (▼) (additional monitoring | Black Triangle (▼)) additional monitoring |
| Head-to-head evidence | SURMOUNT-5 (NEJM, 2025): tirzepatide produced greater average weight loss than semaglutide 2.4mg over 72 weeks in adults with obesity and no diabetes. Wegovy 7.2mg narrows the gap. | |
For more on the direct comparison, our full Wegovy vs Mounjaro page goes through the trial evidence in detail. If you're specifically curious about why there's a cost difference between the two, that has its own explanation.
Step 3: Know what to raise with your prescriber, and when it's urgent
Feeling hungrier after a switch is worth reporting to whoever is managing your treatment, but it's rarely urgent on its own. The things that warrant a prompt call are: losing no weight at all after 12 or more weeks on a stable maintenance dose, hunger so severe that you're eating significantly more than before you started any treatment, or any new physical symptoms (persistent stomach pain, nausea that hasn't settled after two weeks on the same dose, injection-site problems). The NHS patient information on semaglutide sets out the side-effect profile to watch for.
At nume, every repeat order goes back to a prescriber for review, the same process runs whether you're asking about a dose change or flagging that appetite control has slipped. If you placed your order before noon and the prescriber approves it, the pen leaves our pharmacy the same day (a detail patients often appreciate if they're managing a weekly injection schedule around work or the school run). You can read about other patients' experiences switching between these medicines, or explore the full range of treatments we can discuss.
One thing the SURMOUNT-5 head-to-head trial makes clear: both medicines produce meaningful weight loss. The question is which suits your biology, your history, and your clinical picture. That is a decision our prescribers work through with you, not something a comparison table can settle.
If you're ready to talk it through, speak to our prescribers via a free consultation. And if you've already switched from Mounjaro to Wegovy and want to understand what to expect next, or you're still weighing up whether to switch from Mounjaro to Wegovy in the first place, both of those guides walk you through the detail. If you'd like to know more about the team reviewing your case, our clinical lead's profile is there to read.
Looking to start your weight loss journey?
Take a quick eligibility quiz to explore your options and see how we can support you.