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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How Do I Qualify For Mounjaro in the UK?
Mounjaro (tirzepatide) is a prescription-only weight management injection available in the UK, but not everyone is eligible for it. Eligibility depends on your BMI, health conditions, age, and whether you access it through the NHS or privately. This guide explains the exact criteria, how the qualification process works, and what to expect when assessing whether Mounjaro is right for you.
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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.
UK Eligibility Criteria for Mounjaro
To qualify for Mounjaro in the UK, you must meet specific BMI thresholds and health criteria. Adults with a BMI of 30 kg/m² or above are generally eligible. If your BMI is between 27 and 29.9 kg/m², you may still qualify if you have at least one weight-related health condition, such as type 2 diabetes, prediabetes, high blood pressure, abnormal blood fats (dyslipidaemia), obstructive sleep apnoea, or a history of heart attack or stroke.
If you are of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds — you may be eligible at BMI 27.5 or above, as these populations face higher cardiovascular and diabetes risks at lower BMI levels. You must also be at least 18 years old. Mounjaro is prescription-only, so qualification requires a clinical assessment from a licensed prescriber or NHS specialist service.
Our free BMI calculator above can help you determine your BMI instantly, which is the first step in assessing eligibility.
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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.
Who Cannot Take Mounjaro
Mounjaro is not suitable if you are pregnant, planning to become pregnant, or breastfeeding. You cannot take it if you have a severe allergy to tirzepatide or any ingredients in the KwikPen device. If you have severe gastroparesis or serious digestion problems, Mounjaro may not be appropriate due to how it affects stomach emptying.
Additionally, Mounjaro is not recommended if you have a personal or family history of medullary thyroid cancer or multiple endocrine neoplasia type 2. Your prescriber will review your full medical history during assessment. If you have any concerns about medical conditions, medications you are taking, or whether Mounjaro is safe for you, discuss this with your GP before pursuing a prescription.
- 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 BMI do I need to qualify for Mounjaro?
You generally qualify if your BMI is 30 kg/m² or above. If your BMI is 27–29.9 kg/m², you may qualify if you have a weight-related health condition like type 2 diabetes, high blood pressure, or sleep apnoea. Use our free BMI calculator to check your BMI instantly.
Can I get Mounjaro on the NHS in the UK?
Yes, Mounjaro is available through NHS specialist weight management services (tier 3 and tier 4). However, access is limited and varies significantly by region. You typically need a referral from your GP to a specialist service. Waiting lists can be several months to years in many areas. Private online prescribing is an alternative if NHS access is not available locally.
How do I apply for Mounjaro on the NHS?
Speak to your GP about your weight and eligibility. Your GP can refer you to a tier 3 specialist weight management service in your area. The service will assess your BMI, health conditions, and suitability for Mounjaro. NICE has approved tirzepatide for NHS use, but availability depends on your local Integrated Care Board (ICB) funding and capacity.
What's the difference between Mounjaro and Wegovy?
Both are prescription-only weight loss injections approved in the UK. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, while Wegovy (semaglutide) is a GLP-1 receptor agonist only. Mounjaro starts at 2.5 mg and goes up to 15 mg weekly, while Wegovy goes up to 2.4 mg weekly. Clinical trials showed similar average weight loss, but individual results vary. Your prescriber will recommend the most suitable option.
Do I need a clinical assessment before getting Mounjaro?
Yes, absolutely. Mounjaro is prescription-only and requires a clinical assessment before dispensing. A licensed prescriber will review your medical history, current medications, weight, BMI, and health conditions. You will need to confirm you are not pregnant, do not have contraindications, and understand the side effects and lifestyle requirements alongside the medication.
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.