Mounjaro®
Starting from £179.99/mo
Start journey Learn moreMounjaro vs Wegovy: what the evidence actually shows, and how to decide
Step 1: understand what's licensed for weight loss in the UK right now
Two injectable treatments are currently licensed in the UK specifically for weight management in adults: Mounjaro (tirzepatide), made by Eli Lilly, and Wegovy (semaglutide), made by Novo Nordisk. That's it. Ozempic is also semaglutide, but it holds a licence for type 2 diabetes only, it is not licensed for weight loss, and presenting it as an alternative to Mounjaro for that purpose would be clinically misleading. Saxenda (liraglutide) is licensed for weight management but is no longer dispensed by nume.
Both Mounjaro and Wegovy are prescription-only medicines, meaning you cannot obtain them legally without a clinical assessment. Mounjaro is a dual GIP and GLP-1 receptor agonist, it activates two gut-hormone pathways simultaneously, slowing gastric emptying and reducing appetite. Wegovy acts on the GLP-1 pathway only. That mechanistic difference is one reason the trial results diverge.
A practical check worth doing in under a minute: look up any online pharmacy on the GPhC register before handing over any personal or payment details. Legitimate services are listed there; unregistered sellers are a warning sign.
Step 2: compare what the clinical trials found, fairly
The numbers below come from the pivotal UK-relevant trials. They are averages across thousands of participants, individual results vary, and no treatment guarantees any specific outcome.
| Factor | Mounjaro (tirzepatide) | Wegovy 2.4mg (semaglutide) | Wegovy 7.2mg (semaglutide) |
|---|---|---|---|
| Mechanism | Dual GIP + GLP-1 agonist | GLP-1 agonist | GLP-1 agonist |
| Average weight loss (trial) | ~20–21% at 15mg over 72 weeks (SURMOUNT-1, NEJM) | ~15% over 68 weeks (STEP 1, NEJM) | ~20.7% over 72 weeks (MHRA approval data) |
| Head-to-head vs semaglutide 2.4mg | Greater average loss (SURMOUNT-5, NEJM 2025) | Reference arm | Not directly compared to tirzepatide |
| UK licence (weight management | Yes (BMI ≥30, or ≥27 with a weight-related condition) | Yes (BMI ≥30, or ≥27 with a weight-related condition) | Yes) BMI ≥30 only (approved April 2026) |
| Injection frequency | Once weekly | Once weekly | Once weekly |
| NICE recommendation | TA1026 (Dec 2024) | TA875 (Mar 2023) | Within TA875 framework |
The SURMOUNT-5 trial published in the New England Journal of Medicine (2025) was the first direct head-to-head comparison of tirzepatide and semaglutide 2.4mg in adults with obesity and no diabetes. Over 72 weeks, tirzepatide produced greater average weight reduction. The 7.2mg Wegovy dose (approved by the MHRA in January 2026 and available as a dedicated single-dose pen from April 2026) narrows that gap considerably, reaching around 20.7% average loss. Which of these figures is relevant to you personally depends on which dose a prescriber considers appropriate for your circumstances.
Step 3: look beyond the headline percentages
Trial averages are a starting point, not a prediction. Several factors shift the comparison in practice. Tolerability matters: both treatments share a broadly similar gastrointestinal side-effect profile, nausea, loose stools and indigestion are the most common complaints, typically peaking after a dose increase and settling over days to weeks, as detailed on the NHS tirzepatide medicines page and the equivalent semaglutide page. Some people tolerate one better than the other, and that's a conversation worth having with your prescriber rather than assuming.
Contraception and HRT are also relevant here. Women taking oral contraceptives should add a non-oral method for the first four weeks of Mounjaro and for four weeks after each dose increase, because the pill's absorption may be affected; there is no equivalent guidance for semaglutide. If you use oral HRT, your prescriber may consider transdermal alternatives while on tirzepatide. These aren't reasons to avoid either medicine, they're factors to disclose at consultation. You can read more about the practical side of how Mounjaro is used before your assessment.
Cost context: Eli Lilly raised Mounjaro's UK list price from September 2025, with the highest dose's list price rising to around £330 per four-week pen; private prices typically range roughly £149–£375 per month depending on dose and provider. The Eli Lilly price increase affected the whole market. Wegovy pricing sits in a comparable range. Neither medicine is cheap, and neither should be, supply-chain safety and clinical oversight are part of what a legitimate price covers.
Step 4: let a prescriber weigh it up with your full picture
Reading a comparison table can take you a long way, but it cannot account for your medical history, current medications, comorbidities or previous treatment. That's exactly what our clinical team assesses during a consultation. At nume, your responses are read by a GPhC-registered Independent Prescriber on the same day (not processed by an algorithm) and if treatment is approved and dispatched before 12pm, it arrives the next working day.
Both Mounjaro and Wegovy are available through our treatment service following a clinical assessment. If you'd like to understand more about how the injection itself works before you decide, the injection site guidance page covers where on the body to administer the pen and how to rotate locations safely, and our frequently asked questions are good places to start, alongside a closer look at the specific injection sites used with Mounjaro for weight loss. The short answer to whether one is better than the other is: it depends, and finding out which applies to you is the point of the consultation.
Which treatment suits you is a clinical decision our prescribers make with you, based on your individual assessment.
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