Mounjaro®
Starting from £179.99/mo
Start journey Learn moreHow the numbers differ, what drives them, and how the two medicines actually compare
Step 1: Understand what the dose number is actually measuring
Tirzepatide (Mounjaro) and semaglutide (Wegovy) are chemically very different molecules. Tirzepatide is a larger, more complex peptide that activates two receptors (GIP and GLP-1) while semaglutide targets only GLP-1. Because they are structurally distinct, their doses are calibrated independently: the number on the pen reflects how much of that specific molecule a manufacturer determined was safe and effective, not how potent it is relative to the other medicine.
Think of it this way: 500 mg of one antibiotic is not more powerful than 50 mg of a different antibiotic. The figures only mean something within the same drug class and, even then, only once the pharmacology is accounted for. Wegovy's 2.4 mg and Mounjaro's 15 mg exist on separate scales. The difference between Wegovy and Mounjaro doses is a feature of chemistry, not a ranking of strength.
The NHS medicines guidance for tirzepatide and the NICE appraisal of both medicines (TA1026 for tirzepatide, TA875 for semaglutide) treat each on its own terms precisely because the dose numbers are not interchangeable.
Step 2: See how the titration ladders are structured
Both medicines start low and increase gradually, giving your body time to adjust and reducing the chance of nausea or other gastrointestinal discomfort. The route to the maintenance dose looks quite different on paper.
| Feature | Mounjaro (tirzepatide) | Wegovy injection (semaglutide 2.4 mg) |
|---|---|---|
| Mechanism | Dual GIP + GLP-1 receptor agonist | GLP-1 receptor agonist |
| Starting dose | 2.5 mg | 0.25 mg |
| Standard maintenance dose | Up to 15 mg | 2.4 mg (up to 7.2 mg, approved April 2026) |
| UK strengths available | 2.5 / 5 / 7.5 / 10 / 12.5 / 15 mg | 0.25 / 0.5 / 1.0 / 1.7 / 2.4 / 7.2 mg |
| Average weight loss (trial, 72 weeks) | ~20–21% at 15 mg (SURMOUNT-1, NEJM) | ~15% at 2.4 mg (STEP 1, NEJM); ~20.7% at 7.2 mg |
The titration steps are also sized differently. Mounjaro increases by 2.5 mg at a time; Wegovy's steps are fractions of a milligram. Neither ladder is objectively steeper, they reflect what each molecule requires to reach therapeutic effect. If you want to understand how specific dose points line up, the Mounjaro equivalent dose to Wegovy page explores that question in detail.
Step 3: Look at what the clinical trials actually showed
When the SURMOUNT-5 trial compared the two medicines head-to-head, tirzepatide produced greater average weight loss than semaglutide 2.4 mg over 72 weeks in adults with obesity and no diabetes, a finding published in the New England Journal of Medicine in 2025 and referenced in the NICE appraisal of tirzepatide (TA1026). But the 7.2 mg Wegovy dose, approved by the MHRA on 14 April 2026, narrows that gap, reporting around 20.7% average weight loss in trials.
This matters for the dose-number question: tirzepatide's higher numerical dose range is not what makes it effective. Its dual-receptor action means it produces meaningful results at doses that, measured in milligrams, happen to be larger than semaglutide's. The two are simply different drugs, dosed on different scales, evaluated in separate programmes. If you are already on Mounjaro and wondering what dose of Wegovy lines up with 7.5 mg Mounjaro, that question has its own dedicated page. For a broader side-by-side, the Wegovy vs Mounjaro comparison covers efficacy, side-effect profiles and licensing in full.
Both medicines carry a Black Triangle (▼) designation, meaning the MHRA monitors them with additional vigilance, worth knowing regardless of which you are considering. The NHS patient guide to tirzepatide and the equivalent semaglutide page are the most practical starting points for understanding the side-effect picture for each.
Step 4: What this means when you're choosing between them
The dose number is the wrong thing to lead with when deciding which medicine suits you. The right questions are clinical ones: your BMI, any weight-related conditions, your medical history, what medicines you already take, and your own priorities around injection vs tablet, titration schedule and monitoring. Some patients find one medicine better tolerated than the other; some reach their goals faster on one than the other. There is no universal answer.
The question of why Mounjaro's dose appears higher is one our prescribers address regularly, it comes up most in consultations booked after people have spent an evening comparing packaging. If you're deciding which suits you, our free consultation page is the place to start. A named prescriber reads your answers and, if treatment is clinically right for you, we dispatch the same day, which, if you're booking on a Monday before noon, means your first pen arrives Tuesday. Cost is a fair consideration too; the cost comparison between Wegovy and Mounjaro page sets out what private prescriptions typically look like across both medicines.
Which treatment is right for you is a clinical decision our prescribers make with you, not a number on a box.
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