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 Injection on the NHS — Complete UK Guide
Mounjaro (tirzepatide) is a prescription-only weekly weight loss injection that has been approved by NICE for use within NHS specialist weight management services. This guide explains NHS eligibility, how to access Mounjaro through the NHS, and how it compares to private options in the UK. Understanding both routes can help you decide the best path forward for your weight management journey.
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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 Access Routes for Mounjaro
Mounjaro is a GIP and GLP-1 receptor agonist — a dual-action weekly weight loss injection licensed for UK weight management. NICE has approved tirzepatide for use in NHS specialist services, but access is not through your GP surgery. Instead, you'll need referral to a tier 3 weight management service, which is a specialist multidisciplinary team.
NHS eligibility criteria:
- 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, high blood pressure, abnormal cholesterol, sleep apnoea, or cardiovascular disease history)
- Lower BMI thresholds apply for South Asian, Chinese, Black African, and Black Caribbean adults (BMI 27.5+)
To access Mounjaro on the NHS, your GP must refer you to your regional tier 3 service. However, availability varies significantly by area, and waiting lists can be very long (often 6–18 months in many regions). Use our free BMI calculator to check whether you might meet NHS criteria.
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.
NHS vs Private Access — What You Need to Know
The NHS route offers Mounjaro at no cost to you if approved by your tier 3 service, but waiting times and regional availability are significant barriers. Private access is available immediately through GPhC-registered online prescribing services, where a UK-licensed prescriber conducts a clinical assessment. Private Mounjaro typically costs £129–£320 per month depending on dose.
Both routes require a clinical assessment to confirm suitability — Mounjaro is prescription-only and not suitable for everyone. Your prescriber will review your medical history, current medications, and weight management goals. Track your progress once started using our free progress tracker, and combine treatment with a reduced-calorie diet and increased physical activity for best results.
- 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.
Can I get Mounjaro on the NHS straight from my GP?
No. Mounjaro is only prescribed through specialist tier 3 weight management services, not by GPs. You must be referred by your GP to your regional service. Availability varies widely — some areas have short waiting lists, others have waits of 12+ months. Contact your local integrated care board (ICB) to find your nearest tier 3 service.
How long does it take to get Mounjaro on the NHS?
This varies significantly by region. Some specialist services have waiting lists of 3–6 months, while others have waits exceeding 18 months. NHS capacity for weight management services has increased, but demand remains high. Ask your GP to refer you as soon as possible if you meet eligibility criteria.
What is a tier 3 weight management service?
Tier 3 services are specialist multidisciplinary teams typically based in hospital settings or community clinics. They include doctors, dietitians, psychologists, and specialist nurses. They assess suitability for medications like Mounjaro, provide lifestyle support, and monitor your progress with regular appointments and blood tests.
Is Mounjaro available on the NHS in all UK regions?
NICE has approved Mounjaro for NHS use, but implementation and availability vary. Some English ICBs have approved it, others are still implementing access. Scotland, Wales, and Northern Ireland have their own approval pathways. Check with your local NHS service or ask your GP about availability in your area.
How does the private Mounjaro route work in the UK?
Private prescribers conduct an online consultation, review your medical history, and issue a prescription if appropriate. A GPhC-registered pharmacy dispenses your Mounjaro. You manage your own progress and can contact the prescriber with questions. Private access is faster but costs apply, and you're responsible for ongoing monitoring.
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.