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- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
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Mounjaro 7.5mg vs Wegovy — UK Comparison Guide
If you're looking at weight loss options in the UK, you've probably heard about both Mounjaro (tirzepatide) and Wegovy (semaglutide). Both are prescription-only GLP-1-based injections, but they work differently and have different costs. This guide compares them at the 7.5mg Mounjaro dose level so you can understand how they differ and what a prescriber might recommend based on your individual health needs.
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What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
How Mounjaro and Wegovy Work — Key Differences
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist. This dual action means it activates two natural hormone pathways instead of one — the GIP pathway and the GLP-1 pathway. This dual mechanism may give it a slightly different weight loss profile compared to single-action medications.
Wegovy (semaglutide) is a GLP-1 receptor agonist only. It activates the GLP-1 pathway, which signals fullness, reduces appetite, and slows gastric emptying. Clinical trials (the STEP trials) showed Wegovy helped participants lose approximately 14.9% of body weight on average at the maximum dose.
Clinical trial data from SURMOUNT-1 showed that Mounjaro at 7.5mg produced average weight loss of around 19.5% of body weight — though individual results vary significantly. Both medications require a reduced-calorie diet and increased physical activity to be effective. A prescriber will assess which mechanism suits your individual health needs.
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Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
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Cost, Dosing, and Individual Suitability
Private UK costs for both medications vary by dose and provider, typically ranging from £129–£320 per month depending on the specific dose and supplier. At the 7.5mg dose, Mounjaro KwikPen pricing is generally in the mid-range of available options. Wegovy, with its slower dose titration, may require more injections to reach maintenance dose, which can affect overall cost depending on the provider's pricing structure.
Prescribers choose between Mounjaro and Wegovy based on individual factors: your health history, any other medications you're taking, previous medication responses, and personal health goals. Both are prescription-only and require a clinical assessment. NHS access is through specialist tier 3 weight management services where available. Your GP or a licensed prescriber can assess which medication might be most suitable for your circumstances.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
Is Mounjaro 7.5mg cheaper than Wegovy in the UK?
Cost varies by provider and dose. Mounjaro 7.5mg and Wegovy 1.7mg (approximate equivalent dose) typically cost between £129–£320 per month privately, depending on the supplier. Compare prices across GPhC-registered pharmacies for your specific dose.
What's the main difference between Mounjaro and Wegovy?
Mounjaro is a dual GIP+GLP-1 receptor agonist (two mechanisms), while Wegovy is a GLP-1 agonist only (one mechanism). This dual action in Mounjaro may produce slightly different weight loss results. Individual responses vary significantly.
Which one loses more weight — Mounjaro or Wegovy?
Clinical trials showed Mounjaro produced average weight loss of around 19.5% at 7.5mg and up to 20.9% at maximum dose, versus Wegovy's average of 14.9% at maximum dose. However, individual results vary — some people respond better to one than the other.
Can my GP prescribe Mounjaro or Wegovy directly?
NHS prescription is typically through specialist tier 3 weight management services, not standard GP prescription. Private prescriptions are available through GPhC-registered online pharmacies following a clinical assessment by a UK-licensed prescriber.
How do I know which medication is right for me?
A prescriber will assess your health history, medications, BMI, and any weight-related conditions. Both require clinical assessment. Use our free BMI calculator and GLP-1 weight loss calculator to understand your baseline and potential weight loss projections before your consultation.
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