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 Weight Loss Medication — NHS and UK Information
Mounjaro (tirzepatide) is a prescription weight loss medication licensed in the UK for managing excess weight in adults. It's available through NHS specialist tier 3 weight management services and private prescribing routes. This guide explains NHS eligibility criteria, how NICE has approved tirzepatide within UK specialist services, how the medication works, and what you can expect. Whether you're considering Mounjaro through the NHS or exploring private options, understanding the UK prescribing landscape is essential.
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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.
NHS Access and UK Eligibility for Mounjaro
In the UK, Mounjaro is available through NHS specialist weight management services (tier 3), not standard GP prescriptions. NICE (the National Institute for Health and Care Excellence) has approved tirzepatide for use within these specialist services for adults with a BMI of 30 kg/m² or above, or 27–29.9 kg/m² with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease.
For people of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds apply due to higher metabolic risk — eligibility may start at BMI 27.5 or above. NHS access typically requires referral from your GP to a tier 3 specialist service, and availability varies significantly across UK regions (Integrated Care Boards). Waiting lists in many areas are substantial.
- Clinical trials showed Mounjaro helped participants lose an average of 15–21% body weight over 72 weeks, alongside a reduced-calorie diet and increased physical activity.
- Individual results vary based on dose escalation, lifestyle factors, and personal response.
- Mounjaro is a dual GIP and GLP-1 receptor agonist — different mechanism from other weight loss injections like Wegovy.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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.
Private vs NHS Routes for Mounjaro in the UK
NHS route: Referral to a specialist tier 3 service, clinical assessment, and prescription through that service. No upfront cost (on prescription). Significant waiting lists in many regions.
Private route: Online consultation with a UK-licensed prescriber, prescription issued if clinically appropriate, and dispensed by a GPhC-registered pharmacy. Available immediately without NHS referral. Costs typically range from £130–£320 monthly depending on dose.
Both routes require a clinical assessment to confirm eligibility. Our GLP-1 weight loss calculator can help you estimate potential weight loss at different Mounjaro doses, and our BMI calculator will confirm whether you fall within eligibility thresholds for UK weight management treatment.
- 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 Mounjaro and how does it work?
Mounjaro (tirzepatide) is a prescription weight loss injection licensed in the UK. It's a dual GIP and GLP-1 receptor agonist that helps regulate appetite, reduce food cravings, and support feeling fuller after meals. It's given as a once-weekly injection and comes in a pre-filled KwikPen device.
Am I eligible for Mounjaro on the NHS?
You may be eligible if you have a BMI of 30 kg/m² or above, or 27–29.9 kg/m² with weight-related health conditions like type 2 diabetes or high blood pressure. South Asian, Chinese, Black African, or Black Caribbean adults may be eligible at lower BMI thresholds. Your GP can refer you to a specialist tier 3 weight management service for assessment.
How long does it take to get Mounjaro on the NHS?
NHS waiting times vary significantly by region. Many areas have waiting lists of several months to over a year for specialist tier 3 services. Your GP can advise on waiting times in your area. Private prescribing typically offers faster access without NHS referral.
What are the main side effects of Mounjaro?
Very common side effects include nausea, diarrhoea, vomiting, and constipation. These often improve over time as your body adjusts. Less common side effects include fatigue, dizziness, and injection site reactions. Always discuss any concerns with your prescriber.
Is Mounjaro or Wegovy better for weight loss in the UK?
Both are licensed for weight loss in the UK. Mounjaro showed average weight loss of 15–21% in clinical trials, whilst Wegovy showed approximately 15%. Mounjaro uses a dual GIP/GLP-1 mechanism versus Wegovy's single GLP-1 mechanism. Individual response varies. Your prescriber can advise which is suitable for you.
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.