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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Will My GP Prescribe Mounjaro on the NHS?
Whether your GP will prescribe Mounjaro depends on several factors, including your BMI, health conditions, and access to specialist services in your area. In the UK, Mounjaro (tirzepatide) is approved by NICE for weight management, but NHS prescribing happens through specialist tier 3 weight management services — not standard GP prescription. Your GP can refer you to these services, but many areas have long waiting lists. Private prescription routes are also available. This guide explains your options and what the current NHS position means for you.
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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 Prescribing and Tier 3 Services
Mounjaro is available on the NHS, but through a specific pathway. NICE (the National Institute for Health and Care Excellence) has approved tirzepatide for use within NHS specialist weight management services — tier 3 and tier 4 services. This means your GP cannot simply prescribe Mounjaro directly; instead, you need to be referred to a specialist multidisciplinary weight management team. These teams assess you against strict eligibility criteria and manage your treatment.
- BMI of 30 kg/m² or above (or 27–29.9 with weight-related health conditions like type 2 diabetes, high blood pressure, or obstructive sleep apnoea)
- Lower thresholds apply for South Asian, Chinese, Black African, and Black Caribbean adults (BMI 27.5+)
- Failure to lose weight with tier 2 interventions (primary care lifestyle programmes)
The challenge is that tier 3 services are overstretched across much of the UK. Many areas have waiting lists measured in months or even years. Availability varies significantly by region (integrated care board). Even when you meet eligibility criteria, your area may have limited funding or a closed pathway, meaning you cannot access Mounjaro through the NHS at all. Your GP can advise you about local availability.
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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.
Private Prescription and Your Alternatives
If NHS access is not available in your area or waiting times are prohibitive, Mounjaro is available through private prescription. UK-licensed prescribers can issue prescriptions following an online clinical assessment without an NHS referral. This is faster (often days, not months) and does not depend on regional NHS funding. However, you pay privately — costs range from approximately £129–£320 per month depending on your dose and provider.
You can also discuss with your GP whether other weight management options might be available sooner through the NHS, such as tier 2 programmes or other lifestyle interventions. Your GP may also be able to tell you when your local tier 3 service might have capacity or suggest alternative services. Use our free BMI calculator above to check your current BMI and confirm your eligibility baseline.
- 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 the difference between NHS and private Mounjaro prescription?
NHS Mounjaro is prescribed through specialist tier 3 weight management services after GP referral, but is limited by regional funding and waiting lists. Private Mounjaro is available faster (days rather than months) through online clinical assessment with a UK-licensed prescriber, but you pay the full cost. Both require a prescription and clinical assessment.
How long is the NHS waiting list for Mounjaro?
Waiting times vary significantly by region. Some areas have waiting lists of several months; others are temporarily closed to new referrals due to demand. Your GP can tell you the current situation for your local integrated care board. You can also contact your local tier 3 service directly to ask about current waiting times and capacity.
Can I ask my GP to prescribe Mounjaro privately?
Yes, you can ask your GP to refer you to a private prescriber or refer you to an online prescribing service. Your GP cannot prescribe Mounjaro privately themselves (it is not a standard GP medication), but they can provide any medical history needed for your private clinical assessment. Some private clinics can arrange this directly without GP involvement.
What if I don't meet the BMI criteria for Mounjaro?
If your BMI is below 27, you may not currently meet standard criteria. However, eligibility is individual and depends on health conditions. Your GP can assess whether you have weight-related health issues that might change your eligibility. You can use our free BMI calculator to check your current BMI and discuss options with your GP.
Is tirzepatide available on the NHS under a different name?
Mounjaro is the brand name for tirzepatide approved in the UK. It is not sold under another name on the NHS. Ozempic (also made by Eli Lilly) contains a different medication (semaglutide) and is approved for type 2 diabetes, not weight management. Always check the brand name and approval indication with your prescriber.
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.