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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Mounjaro vs Wegovy: UK Price and Cost Comparison
Mounjaro and Wegovy are the two most commonly prescribed GLP-1 weight loss injections in the UK, but they differ in price, mechanism, and how they're accessed. Both are prescription-only medicines available through NHS specialist services or private online prescribing, with costs varying significantly depending on dose and provider. Understanding the price difference and what each medication offers can help you make an informed decision with your GP or prescriber.
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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 Work Differently
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, meaning it activates two natural hormone pathways to help reduce appetite and support weight loss. Wegovy (semaglutide) is a GLP-1 receptor agonist only, activating a single pathway. Clinical trial data shows the difference: in the SURMOUNT-1 trial, Mounjaro at 15 mg helped participants lose an average of approximately 20.9% of body weight over 72 weeks, whilst the STEP-1 trial showed Wegovy at 2.4 mg resulted in approximately 14.9% average weight loss. However, individual results vary significantly, and both medications work best alongside a reduced-calorie diet and increased physical activity. Your prescriber will assess which mechanism suits your individual health profile.
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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
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UK Pricing and Access Routes
Private costs in the UK range from approximately £129–£320 per month depending on dose, with Mounjaro typically available at higher doses and potentially higher monthly costs. Wegovy pricing is often comparable at lower doses but increases with escalation. NHS access is available through specialist tier 3 weight management services if referred by your GP, though availability and waiting times vary significantly by region. Both require a clinical assessment before prescription. Our GLP-1 weight loss calculator can help you understand potential outcomes at different doses, whilst our BMI calculator provides your baseline for discussing eligibility with your prescriber.
- 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.
What is the average cost of Mounjaro in the UK?
Private Mounjaro costs typically range from £180–£320 per month depending on dose. The 2.5 mg starting dose is usually cheaper than higher maintenance doses (10–15 mg). NHS access is available through specialist services but varies by region. Always check current pricing with your chosen provider, as costs fluctuate.
Is Wegovy cheaper than Mounjaro in the UK?
Pricing is often comparable at similar weight loss effectiveness levels. Wegovy costs roughly £129–£250 per month privately depending on dose. The main difference is that Mounjaro offers higher maximum doses (15 mg vs 2.4 mg), which may be more costly. Your prescriber will discuss the best option for your circumstances.
Can I get Mounjaro or Wegovy on the NHS?
Yes, both are available through NHS specialist weight management services (tier 3). You'll need a GP referral and assessment. Availability and waiting times vary significantly by region and local commissioning. Private prescription is available without NHS referral through UK-licensed online prescribers.
How much weight can I expect to lose with Mounjaro vs Wegovy?
Clinical trials show Mounjaro at 15 mg achieved approximately 20.9% average body weight loss, whilst Wegovy at 2.4 mg achieved approximately 14.9%. However, individual results vary considerably based on dose, adherence, diet, and lifestyle. Your prescriber can give personalised guidance.
What's the difference between tirzepatide and semaglutide?
Tirzepatide (Mounjaro) is a dual GIP+GLP-1 agonist activating two hormone pathways. Semaglutide (Wegovy) is a GLP-1 agonist only. This dual mechanism in Mounjaro may contribute to slightly higher average weight loss in trials, but both require clinical assessment to determine suitability for you individually.
Ready to take control of your weight loss journey?
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