Mounjaro®
Starting from £179.99/mo
Start journey Learn moreHow Mounjaro and Wegovy compare on mechanism, evidence and practical use
Step 1: understand what each medicine actually does
Mounjaro (tirzepatide, made by Eli Lilly) is a dual GIP and GLP-1 receptor agonist, it activates two separate gut-hormone pathways that regulate appetite and blood-sugar levels. Wegovy (semaglutide, made by Novo Nordisk) is a GLP-1 receptor agonist only, targeting one of those same pathways. Both slow gastric emptying and reduce appetite; tirzepatide's additional GIP action is what makes it mechanistically distinct. To understand what is the difference between Wegovy and Mounjaro at its simplest: one receptor versus two.
Both are subcutaneous injections taken once a week via pre-filled pen. Treatment with either starts at a low tolerability dose and is titrated upward by the prescriber, typically in four-week steps, to the dose that is both effective and well-tolerated. Wegovy's standard maintenance dose has been 2.4 mg; a higher 7.2 mg pen received MHRA approval in April 2026. Mounjaro goes up to 15 mg. Our Wegovy overview page sets out the full semaglutide schedule in detail. The NHS medicines page on tirzepatide is a useful starting point for factual background on how Mounjaro works.
Step 2: look at the trial evidence side by side
The clearest trial comparison comes from SURMOUNT-5, a head-to-head study published in the New England Journal of Medicine in 2025. Over 72 weeks, adults with obesity and no diabetes lost significantly more body weight on tirzepatide than on semaglutide 2.4 mg. NICE referenced this indirect comparison when appraising tirzepatide in TA1026. Earlier, SURMOUNT-1 reported average weight reductions of around 20–21% at the 15 mg dose of tirzepatide, while STEP 1 reported around 15% average reduction for semaglutide 2.4 mg. The newer 7.2 mg Wegovy dose reported roughly 20.7% average loss over 72 weeks in trials, which narrows the gap considerably.
All figures come from controlled clinical trials alongside reduced-calorie diet and activity changes; individual results vary, and the difference between semaglutide and Mounjaro in practice depends on the dose reached and how a person's body responds. Our weight management overview puts the evidence in broader clinical context.
| Feature | Mounjaro (tirzepatide) | Wegovy (semaglutide) |
|---|---|---|
| Active ingredient | Tirzepatide | Semaglutide |
| Receptor targets | GIP + GLP-1 (dual) | GLP-1 (single) |
| Top licensed dose | 15 mg | 2.4 mg (standard); 7.2 mg (MHRA-approved Apr 2026) |
| Average trial weight loss (top dose) | ~20–21% (SURMOUNT-1, NEJM) | ~15% at 2.4 mg (STEP 1, NEJM); ~20.7% at 7.2 mg |
| UK licence (weight management) | BMI ≥30, or ≥27 with a weight-related condition | BMI ≥30, or ≥27 with a weight-related condition |
| Head-to-head result | Greater average loss vs semaglutide 2.4 mg (SURMOUNT-5, NEJM 2025) | Comparator in SURMOUNT-5 |
Step 3: check eligibility and what a prescriber weighs up
Both medicines share the same licensed eligibility threshold, adults with a BMI of 30 or above, or 27 and above with at least one weight-related condition such as type 2 diabetes, high blood pressure, high cholesterol or obstructive sleep apnoea. Under UK guidance, lower BMI thresholds apply for some ethnic backgrounds. NICE recommends tirzepatide under TA1026 for BMI ≥35 with a comorbidity on the NHS; private eligibility follows the licensed SmPC, which is broader.
A prescriber deciding between the two looks at your full medical history, any contraindications, which medicines you currently take, and your own preferences around injection experience and titration. The oral Wegovy tablet (approved by the MHRA in June 2026) adds a third option for those who prefer not to inject, something worth raising at consultation. If you are wondering about other comparisons, there is a separate look at how Saxenda and Wegovy differ, and at how Wegovy compares to Ozempic, a medicine licensed for diabetes, not weight loss, which is a common source of confusion. People also sometimes search using different spellings, so we have dedicated pages covering what's the difference between Manjaro and Wegovy, what's the difference between Monjaro and Wegovy, and what's the difference between Munjaro and Wegovy if any of those spellings brought you here.
Step 4: satisfy yourself the pharmacy is legitimate before anything else
Whichever medicine a prescriber recommends, the supply source matters. Both Mounjaro and Wegovy are prescription-only medicines, and the MHRA has warned repeatedly about counterfeit pens circulating online. A quick check: visit the GPhC register at pharmacyregulation.org/registers and enter the pharmacy's name or registration number. Takes under a minute. Unregistered sellers, prices far below the market, and sellers offering medicines without a prior clinical assessment are all red flags, the MHRA asks anyone with concerns to report suspect sellers via Yellow Card.
At nume, every consultation is read by a GPhC-registered Independent Prescriber the same day, medicines come through the licensed UK supply chain, and your prescriber's decision on which treatment is right for you is based on your individual clinical picture. Which of these two medicines suits you is a clinical decision made with you, not one we make in advance. Start your free consultation to get that conversation going.
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