The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- 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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Why Is Mounjaro More Expensive Than Wegovy?
Mounjaro (tirzepatide) prices have risen significantly in the UK, and many people wonder why it costs more than Wegovy (semaglutide). Both are prescription-only weight management injections, but they differ in mechanism, manufacturing costs, and market positioning. Understanding the reasons behind pricing helps you make an informed decision about which medication might suit your health needs. Our GLP-1 weight loss calculator can help you explore potential outcomes at different doses, and your GP or prescriber can assess which option is most appropriate for your circumstances.
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Calculate Your BMI Instantly
Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
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 Differ In Cost And Mechanism
Mounjaro costs more than Wegovy in the UK for several key reasons. First, tirzepatide (Mounjaro's active ingredient) is a dual GIP and GLP-1 receptor agonist — it targets two hormone pathways simultaneously, whereas Wegovy's semaglutide targets GLP-1 only. This dual mechanism requires more complex manufacturing, which increases production costs. Second, Mounjaro is newer to the UK market (approved more recently than Wegovy), and manufacturers typically set higher launch prices. Third, increased demand and limited NHS availability mean private prescribing costs reflect market forces. Wegovy, having been available longer, has established competitive pricing through multiple suppliers. Clinical trial data shows Mounjaro achieved average weight loss of approximately 20.9% at the maximum 15 mg dose, while Wegovy achieved approximately 14.9% at 2.4 mg — but both require a reduced-calorie diet and increased physical activity to achieve results. Individual responses vary significantly.
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How It Works
Three simple steps to understand your weight and take action.
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.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
Prescription Costs, NHS Access, And Which Suits You Better
In the UK, Mounjaro's KwikPen typically costs £150–£320 per month privately, depending on dose, whilst Wegovy costs £129–£250 monthly. On the NHS, both medications are accessed through specialist tier 3 weight management services — not standard GP prescription — and availability varies considerably by region. Your prescriber will assess your eligibility based on BMI (30 or above, or 27–29.9 with weight-related conditions) and suitability. Some patients find Mounjaro more effective; others respond equally well to Wegovy at lower cost. Neither is "superior" — suitability depends on your individual health profile, medical history, and how your body responds. Use our free BMI calculator to check your current status, and discuss options openly with your GP or prescriber, who can recommend the most appropriate choice based on clinical evidence and your specific 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.
Why does Mounjaro cost more than Wegovy in the UK?
Mounjaro (tirzepatide) has dual GIP and GLP-1 mechanism — more complex manufacturing than Wegovy's single GLP-1 action. It's also newer to market. Manufacturing complexity, launch pricing, and increased demand all contribute to higher costs. Both are available privately and via NHS specialist services.
Is Mounjaro more effective than Wegovy?
Clinical trials show Mounjaro achieved slightly higher average weight loss (20.9% vs 14.9%), but individual results vary widely. Neither is universally "better" — your prescriber will assess which suits your health profile, medical history, and individual response best. Both require lifestyle changes alongside medication.
Can I get Mounjaro on the NHS?
Yes, Mounjaro is available through NHS specialist tier 3 weight management services, but access varies significantly by region. Waiting lists can be lengthy. Private access is faster — you need a prescription from a UK-licensed prescriber and clinical assessment. Check eligibility based on BMI and weight-related health conditions.
What's the difference between tirzepatide and semaglutide?
Tirzepatide (Mounjaro) activates GIP and GLP-1 pathways. Semaglutide (Wegovy) activates GLP-1 only. This dual mechanism makes tirzepatide more complex to manufacture, contributing to higher cost. Both slow gastric emptying and reduce appetite. Your GP can advise which mechanism suits you better.
How do I choose between Mounjaro and Wegovy?
Your prescriber will recommend based on your BMI, weight-related health conditions, medical history, contraindications, and individual suitability — not price alone. Both require a prescription and clinical assessment. Cost and availability vary regionally. Discuss all options openly with your healthcare provider to find the best fit.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.