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 NHS Guidelines in the UK
Mounjaro (tirzepatide) has been approved by NICE and is now available through NHS specialist weight management services in the UK. However, NHS access is different from private prescribing — it follows specific eligibility criteria and is delivered through tier 3 specialist services rather than standard GP prescription. Understanding the NHS pathway, regional availability, and how your BMI and health conditions affect your eligibility can help you navigate the process effectively. This guide explains the current NHS guidelines for Mounjaro and how they apply to you.
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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.
NHS Eligibility and Tier 3 Services for Mounjaro
NICE (National Institute for Health and Care Excellence) has approved tirzepatide (Mounjaro) as a weight management treatment within NHS tier 3 specialist weight management services. Eligibility in the UK requires:
- BMI of 30 kg/m² or above, OR BMI of 27–29.9 kg/m² with at least one weight-related health condition (type 2 diabetes, prediabetes, hypertension, dyslipidaemia, sleep apnoea, or cardiovascular disease history)
- For South Asian, Chinese, Black African, or Black Caribbean adults, lower thresholds apply — eligibility may begin at BMI 27.5 or above
- Completion of tier 1 and tier 2 interventions (lifestyle support, diet, exercise programmes) without sufficient weight loss
- Adult age 18 and over with no contraindications (pregnancy, breastfeeding, or allergy)
Access is through your GP or a tier 3 specialist service in your region. Use our free BMI calculator above to check where your BMI falls and whether you may meet initial criteria.
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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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NHS vs Private Access Routes for Mounjaro in the UK
NHS route: Referral through your GP to a tier 3 weight management service. NICE approval means some NHS regions now prescribe Mounjaro, but availability varies significantly — waiting lists can be several months to over a year in many areas. Your prescriber will assess you based on clinical need and regional resources.
Private route: Available through private online prescribing services following an online clinical assessment with a UK-licensed prescriber. No NHS referral needed. Prescription issued if clinically appropriate, dispensed by a GPhC-registered pharmacy. Private access is faster and more flexible but involves a cost. Both routes require a prescription — Mounjaro is not available over-the-counter.
- 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 does NICE approval of Mounjaro mean for NHS patients?
NICE approval means Mounjaro (tirzepatide) is recognised as a clinically effective and cost-effective treatment for weight management in NHS specialist services. It allows NHS-funded prescription, though availability depends on your regional Integrated Care Board (ICB) and local tier 3 services.
What is tier 3 in the NHS weight management pathway?
Tier 3 is specialist multidisciplinary weight management services. This is where prescription medications like Mounjaro are typically initiated. Access requires referral from your GP or tier 2 service and usually involves assessment by a consultant, dietitian, and psychologist.
How long does it take to access Mounjaro through the NHS?
Waiting times vary by region. Many areas have waiting lists of 3–12 months or longer. Contact your local NHS weight management service through your GP to find out the current waiting time in your area.
Are the doses of Mounjaro the same on the NHS as privately?
Yes. Mounjaro KwikPen doses range from 2.5 mg to 15 mg weekly, with dose titration starting at 2.5 mg. Both NHS and private prescribers follow the same dosing schedule, escalating every 4 weeks.
Can my GP prescribe Mounjaro, or do I need a specialist referral?
Currently in the UK, Mounjaro is prescribed through tier 3 specialist weight management services, not standard GP prescription. Your GP can refer you to your local tier 3 service, where a specialist will assess and prescribe if appropriate.
Ready to take control of your weight loss journey?
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