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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What's the Difference Between Mounjaro and Wegovy in the UK?
Mounjaro and Wegovy are both prescription-only weight management injections available in the UK, but they work differently and have distinct costs and access routes. Mounjaro (tirzepatide) uses a dual mechanism targeting two hormone pathways, whilst Wegovy (semaglutide) works on a single pathway. Both are licensed for adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions. Understanding the differences—particularly around cost and how to access them—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.
Cost and Access: Private Wegovy Pricing in the UK
Wegovy is available through both NHS specialist services and private prescription routes in the UK. NHS access requires referral to a tier 3 or 4 specialist weight management service, though availability and waiting times vary significantly by region. Private prescription costs typically range from £129 to £280 per month depending on your dose and prescriber, with the starting dose (0.25 mg) at the lower end and maintenance doses (2.4 mg) at the higher end. You'll need an online consultation with a UK-licensed prescriber, who will assess your eligibility based on your BMI, health conditions, and medical history. Once approved, your prescription is dispensed by a GPhC-registered pharmacy. Both routes require ongoing clinical review to monitor your progress and adjust doses as needed. The dose titration schedule for Wegovy spans approximately 16 weeks, meaning costs accumulate over several months before reaching your maintenance dose.
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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.
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Mounjaro vs Wegovy: Cost, Mechanism, and Access Differences
The main differences between Mounjaro (tirzepatide) and Wegovy centre on mechanism, cost, and dose strength. Mounjaro is a dual GIP and GLP-1 receptor agonist, whilst Wegovy targets GLP-1 alone. In clinical trials, Mounjaro produced an average weight loss of approximately 15–21% body weight, compared to Wegovy's 14.9%. Mounjaro KwikPen doses range to 15 mg weekly, whilst Wegovy maxes at 2.4 mg—meaning Mounjaro's higher doses may offer different escalation flexibility. Both are prescription-only and available privately, though private costs and NHS eligibility criteria overlap. Your GP or prescriber will help determine which suits your individual health profile, medical history, and treatment goals. Use our free GLP-1 weight loss calculator to estimate potential outcomes with either medication.
- 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.
How much does Wegovy cost privately in the UK?
Private Wegovy costs typically range from £129 to £280 per month, depending on your dose level. Starting doses (0.25 mg) are cheaper; maintenance doses (2.4 mg) are more expensive. Costs accumulate over the 16-week titration period before you reach your maintenance dose. Prices vary between prescribers and pharmacies, so it's worth comparing options.
Can I get Mounjaro on the NHS?
Yes, Mounjaro is approved for NHS use through specialist tier 3 and 4 weight management services. However, access varies significantly by region and depends on local Integrated Care Board (ICB) funding decisions. Waiting lists can be long. Your GP can refer you to your local specialist service to check availability.
What's the main difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, whilst Wegovy (semaglutide) works on GLP-1 only. Clinical trials showed Mounjaro produced slightly greater average weight loss (15–21% vs 14.9%), but individual results vary. Both are once-weekly injections licensed for weight management in the UK.
How do I access Wegovy privately in the UK?
You can access Wegovy through a private online consultation with a UK-licensed prescriber. You'll need to complete a health assessment, and the prescriber will check your eligibility based on your BMI and health conditions. If approved, your prescription is sent to a GPhC-registered pharmacy for dispensing. No NHS referral is needed.
Which is cheaper: Mounjaro or Wegovy?
Private costs are broadly similar—typically £129–£280 per month depending on dose. Starting doses of both are cheaper than maintenance doses. NHS access (where available) is free, but waiting times and regional availability differ. Your prescriber can discuss cost alongside clinical suitability for your situation.
Ready to take control of your weight loss journey?
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