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 Comparison & Key Differences
If you're comparing Mounjaro and Wegovy as potential weight loss injections in the UK, cost is likely one of your questions. Both are prescription-only weekly weight loss injections, but they differ in price, mechanism, and clinical evidence. This guide breaks down the real costs of each medication, how they compare in clinical trials, and what affects UK pricing — whether you're accessing them through the NHS or privately.
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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.
Price Comparison & Clinical Trial Results
Mounjaro (tirzepatide) pricing in the UK typically ranges from £140 to £320 per month privately, depending on dose and pharmacy. It's a dual GIP and GLP-1 receptor agonist, meaning it activates two hormone pathways. In the SURMOUNT-1 clinical trial, participants taking 15 mg Mounjaro lost an average of 20.9% of their body weight over 72 weeks — the highest among available UK weight loss injections.
Wegovy (semaglutide) private costs typically range from £129 to £280 per month, also dose-dependent. As a single GLP-1 receptor agonist, it works through one pathway. The STEP-1 trial showed approximately 14.9% average weight loss at the maximum 2.4 mg dose over 68 weeks. Both medications require a reduced-calorie diet and increased physical activity for best results — weight loss is not assured, and individual results 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.
How to Access Each Weekly Weight Loss Injection in the UK
NHS access: Both Mounjaro and Wegovy are available through NHS specialist tier 3 weight management services, but access is limited and varies by region. Your GP can refer you to your local service, though waiting lists can extend many months. NICE has approved tirzepatide (Mounjaro) for NHS use within these specialist pathways.
Private access: Both medications are available through GPhC-registered online pharmacies following an online clinical assessment with a UK-licensed prescriber. No NHS referral needed. You'll receive a KwikPen (Mounjaro) or auto-injection pen (Wegovy) via post. Private prescribing allows faster access — typically days rather than months — but costs are entirely out-of-pocket. A prescriber will assess your suitability based on BMI, health conditions, and medications.
- 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.
Which injection costs less in the UK — Mounjaro or Wegovy?
Wegovy is typically slightly cheaper at entry doses (around £129–£180/month), while Mounjaro ranges £140–£320/month depending on dose. However, prices vary between pharmacies and change regularly. Total cost depends on your individual dose escalation — some people reach maximum dose faster than others, affecting overall expense.
Why is Mounjaro more expensive than Wegovy?
Mounjaro has a higher maximum dose (15 mg vs 2.4 mg) and uses a dual mechanism (GIP + GLP-1), which may involve higher manufacturing costs. Wegovy is single GLP-1 only. Pricing also reflects supply, demand, and individual pharmacy margins — direct comparisons are best made by contacting providers.
Can I get Mounjaro or Wegovy free on the NHS?
Yes, both are available through NHS specialist weight management services without cost, but access is limited to tier 3 services and varies by region. Waiting lists are typically several months to over a year in many areas. Private prescribing offers faster access but requires out-of-pocket payment.
How long does one Mounjaro KwikPen last?
One KwikPen contains four weekly doses — so approximately one month's treatment. You'll need a new pen each month. The same applies to Wegovy auto-injection pens, though doses are smaller per injection.
What affects the final cost of Mounjaro or Wegovy in the UK?
Your escalation schedule (how quickly you move between doses), your maximum maintenance dose, pharmacy choice, and any consultation fees affect total cost. Some private prescribers charge £15–£30 per online consultation; others include this in the medication price. Calculate your likely dose and ask providers for total estimated annual cost.
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.