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 Much Is Mounjaro on the NHS?
Mounjaro (tirzepatide) is available on the NHS through specialist tier 3 weight management services, though availability and cost coverage vary significantly by region. The amount you'll receive depends on your clinical assessment, starting dose, and which integrated care board (ICB) funds your treatment. This guide explains NHS eligibility, NICE recommendations, dose titration, and how the NHS route compares to private prescribing in the UK.
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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 Mounjaro Eligibility and Doses
NHS access to Mounjaro (tirzepatide) is through tier 3 specialist weight management services. NICE has approved tirzepatide for use within these 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, prediabetes, hypertension, or sleep apnoea. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower thresholds (27.5 kg/m² or above) may apply due to higher metabolic risk.
Dose titration on the NHS: Treatment begins at 2.5 mg once weekly, increasing by 2.5 mg increments every 4 weeks to a maximum of 15 mg. Each KwikPen contains 4 weeks' supply (4 injections). Your GP will refer you to a specialist weight management service, where a multidisciplinary team assesses suitability and manages escalation.
- Starting dose: 2.5 mg (weeks 1–4)
- Standard maintenance: 5–10 mg (weeks 5 onwards)
- Maximum: 15 mg once weekly
- Clinical trial data showed average weight loss of 15–21% body weight with tirzepatide, though individual results vary significantly alongside reduced-calorie diet and increased physical activity
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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.
NHS Access vs Private Prescribing
NHS route: Free at point of use (no prescription fee for eligible patients), but requires GP referral to specialist services. Waiting lists for tier 3 services range from weeks to many months depending on your region. Once accepted, ongoing prescriptions and monitoring are NHS-funded. This route includes multidisciplinary support (dietitian, psychologist, clinician) but availability is inconsistent across England, Scotland, Wales, and Northern Ireland.
Private route: Available through GPhC-registered online prescribing services following a clinical consultation. Costs typically range from £129–£320 per month depending on dose and provider. No waiting list, faster access, but you pay the full cost. Private prescribers still require a clinical assessment and may refer you to your GP for monitoring. Use our free GLP-1 weight loss calculator to estimate projected weight loss at different doses.
NHS cost to health system: The NHS bears the full pharmaceutical cost of Mounjaro. One month's supply (4 injections) costs approximately £180–£200 to the NHS, depending on negotiated pricing. For patients, NHS prescriptions cost £9.90 per item (unless exempt). Regional variation: Not all ICBs currently fund tirzepatide through tier 3 services; some offer GLP-1 alternatives (semaglutide/Wegovy, liraglutide/Saxenda) instead. Confirm availability in your area by asking your GP about your local weight management pathway. You can also check your eligibility using our free BMI calculator above to see whether you meet the initial criteria.
- 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.
How much does Mounjaro cost on the NHS?
Mounjaro is free on the NHS (excluding the £9.90 prescription fee unless exempt) when prescribed through specialist tier 3 weight management services. However, not all regions currently fund it — some offer alternative GLP-1 medications instead. Check with your GP about availability in your local integrated care board (ICB).
What is the starting dose of Mounjaro on the NHS?
The NHS starting dose is 2.5 mg once weekly for the first 4 weeks. This is then increased by 2.5 mg increments every 4 weeks, as tolerated and clinically appropriate, up to a maximum of 15 mg. Your specialist team manages all dose adjustments.
Can I get Mounjaro on the NHS without a referral?
No. Mounjaro on the NHS requires a referral from your GP to a tier 3 specialist weight management service. Your GP will assess whether you meet eligibility criteria (BMI ≥30, or ≥27 with weight-related health conditions) and make the referral. Waiting times vary by region.
What's the difference between NHS Mounjaro and private Mounjaro?
NHS Mounjaro is free (prescription fee applies) but involves waiting lists and regional availability. Private Mounjaro costs £129–£320/month, has faster access, and doesn't require an NHS referral. Both require clinical assessment and are prescription-only medicines.
How does Mounjaro compare to Wegovy on the NHS?
Both are GLP-1-based weight loss medications. Mounjaro is a dual GIP/GLP-1 agonist (maximum 15 mg weekly), whilst Wegovy is GLP-1 only (maximum 2.4 mg weekly). Clinical trials showed Mounjaro achieved slightly higher average weight loss, though results vary individually. NHS availability depends on your regional ICB.
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.