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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GLP-1 Mounjaro in the UK — NHS Access and Eligibility
Mounjaro (tirzepatide) is a GLP-1 receptor agonist licensed in the UK for weight management in adults. As a prescription-only medicine, it's available through both NHS specialist services and private online prescribing. Understanding your eligibility, how NHS tier 3 services work, and the difference between NHS and private routes is essential when considering whether this dual GLP-1/GIP medication is right for you. This guide covers UK-specific prescribing, NICE guidance, costs, and what to expect.
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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 and Eligibility Criteria
NICE has approved tirzepatide (Mounjaro) for use within NHS specialist weight management services, marking significant progress for adults with obesity in the UK. However, access is not through your GP's standard prescription — it's through tier 3 (specialist) multidisciplinary weight management services.
You may be eligible for NHS Mounjaro if you:
- Have a BMI of 30 kg/m² or above (obesity), OR
- Have a BMI of 27–29.9 kg/m² (overweight) with at least one weight-related health condition such as type 2 diabetes, prediabetes, high blood pressure, abnormal blood fats, sleep apnoea, or cardiovascular disease history
- Are from South Asian, Chinese, Black African, or Black Caribbean backgrounds with a BMI of 27.5 or above (lower thresholds apply due to higher disease risk)
- Have tried lifestyle changes first and demonstrated commitment to ongoing diet and physical activity changes
Check your BMI using our free BMI calculator to assess your starting point. NHS tier 3 services vary significantly by region — contact your GP to ask about local availability and waiting times, which can be months or longer in many areas.
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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 Mounjaro Access in the UK
NHS route: Referral from your GP to your local tier 3 weight management service (varies by Integrated Care Board). Assessment by a multidisciplinary team. Free prescriptions once approved. Long waiting lists in many regions.
Private route: Online consultation with a UK-licensed prescriber through a GPhC-registered pharmacy. No NHS referral needed. Costs typically £129–£320+ per month depending on dose. Faster access — prescription often issued within days. You remain responsible for ongoing monitoring of blood pressure and side effects; many private providers include follow-up support.
Both routes require clinical assessment. Use our GLP-1 weight loss calculator to explore potential outcomes and help inform your conversation with your healthcare provider about which route suits your situation.
- 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.
Does the NHS prescribe Mounjaro for weight loss?
Yes, NICE has approved tirzepatide (Mounjaro) for NHS use through specialist tier 3 weight management services. However, it's not available from standard GP prescriptions. You need a referral to your local tier 3 service, and availability varies significantly by region. Waiting times can be substantial.
How much does Mounjaro cost on the NHS?
Mounjaro is free on the NHS once approved and prescribed by a tier 3 weight management service, as all prescription medicines are dispensed free of charge (unless you don't qualify for free prescriptions). Private prescriptions cost £129–£320+ per month depending on your dose.
What is a tier 3 weight management service?
Tier 3 services are specialist multidisciplinary weight management teams within the NHS, typically based in hospitals or specialist centres. They assess eligibility, manage medication, and provide ongoing support. They sit between primary care (tier 1/2 — your GP and community programmes) and bariatric surgery (tier 4).
How long is the NHS waiting list for Mounjaro?
Waiting times vary by region and local ICB (Integrated Care Board). Many areas have waiting lists of several months to over a year. Contact your GP or local tier 3 service for current waiting times in your area. Private prescribing offers faster access if you cannot wait.
Is Mounjaro the same as a GLP-1 receptor agonist?
Mounjaro is a dual GIP and GLP-1 receptor agonist — it activates both the GIP and GLP-1 hormone pathways, which distinguishes it from single GLP-1 agonists like Wegovy (semaglutide). This dual mechanism may support appetite regulation and weight loss through two complementary pathways.
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.