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 Medication: NHS Access & UK Prescribing
Mounjaro is a prescription-only weight loss medication (tirzepatide) now available through NHS specialist services and private prescribers in the UK. This guide explains how it works, who can access it through the NHS, and the differences between NHS and private routes. Eligibility depends on your BMI and health conditions, and it's used alongside diet and lifestyle changes, not as a replacement for them.
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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 to Mounjaro: Eligibility and Tier 3 Services
In the UK, Mounjaro is accessed through NHS specialist weight management services, typically at tier 3 level — this is a step above your GP surgery. NICE has approved tirzepatide for NHS use, but access varies significantly by region and specialist service availability.
NHS eligibility criteria:
- BMI of 30 kg/m² or above (obesity), OR
- BMI of 27–29.9 kg/m² with weight-related health conditions (type 2 diabetes, high blood pressure, sleep apnoea, cardiovascular disease)
- For South Asian, Chinese, Black African, and Black Caribbean adults, lower thresholds apply — eligibility may start at BMI 27.5 or above
You'll normally need a GP referral to a tier 3 weight management service, and waiting times vary considerably across England, Scotland, Wales, and Northern Ireland. Some areas have substantial waiting lists.
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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.
NHS vs Private Access: What's the Difference?
The NHS route is free at point of use but involves referral, assessment, and often waiting times. Private prescribing is faster — you can have a consultation and receive your prescription within days — but costs between £130–£250 per month depending on your dose. Both routes require a clinical assessment from a UK-licensed prescriber.
With NHS access, you'll receive ongoing monitoring and support from a multidisciplinary team. Private prescribers also provide follow-up, but the model is different. Both require you to commit to lifestyle changes alongside the injection. Use our free GLP-1 weight loss calculator to explore potential outcomes at different Mounjaro doses, and the BMI calculator to check your current eligibility.
- 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 GIP receptor and GLP-1 receptor agonist — a dual-action injection that mimics two natural gut hormones. It helps regulate appetite, reduces food cravings, and supports feeling fuller after smaller meals. It's given as a once-weekly injection (Mounjaro KwikPen) and requires a prescription.
What are the NHS eligibility criteria for Mounjaro?
You're eligible for NHS Mounjaro if you have a BMI of 30 or above, or 27–29.9 with weight-related health conditions like type 2 diabetes, high blood pressure, or sleep apnoea. Lower thresholds apply for South Asian, Chinese, Black African, and Black Caribbean patients. Your GP can refer you to a tier 3 specialist service.
How long are NHS waiting lists for Mounjaro?
Waiting times vary significantly by region and local NHS integrated care board (ICB). Some areas have waiting lists of several months to over a year. Contact your local tier 3 weight management service for current wait times, or discuss private access with a prescriber if NHS waits are lengthy.
What's the difference between NHS and private Mounjaro prescribing?
NHS is free but involves referral and waiting times; private costs £130–£250 monthly and is faster (days to access). Both require clinical assessment and commitment to lifestyle changes. NHS offers integrated multidisciplinary support; private prescribers provide ongoing follow-up via consultation.
Can I switch between NHS and private Mounjaro?
Yes, many patients move between routes depending on waiting times and circumstances. If you start private and later access NHS services, inform both prescribers. Conversely, if NHS becomes available while using private, you can transition. Always notify your prescriber of any changes to avoid gaps or dose conflicts.
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.