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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Do Doctors Prescribe Mounjaro in the UK?
Yes, GPs and specialist doctors can prescribe Mounjaro (tirzepatide) in the UK, but availability and access vary significantly by region. Mounjaro is a prescription-only weight management injection that requires a clinical assessment before being prescribed. Access through the NHS typically goes through specialist tier 3 weight management services, while private prescriptions are available through UK-licensed online prescribers. This guide explains how prescription access works, eligibility criteria, and what the process involves.
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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.
How Mounjaro Prescription Access Works in the UK
Mounjaro (tirzepatide) prescription access in the UK operates through two distinct routes: NHS and private.
NHS access: GPs cannot prescribe Mounjaro directly from their surgery. Instead, you must be referred to a specialist tier 3 or tier 4 weight management service. NICE (National Institute for Health and Care Excellence) approved tirzepatide for use within NHS specialist weight management services, but availability varies significantly by region. Some areas have well-established services; others have lengthy waiting lists or limited access. Your GP can discuss referral options and whether you might be eligible.
Private access: You can obtain a Mounjaro prescription from a UK-licensed prescriber without an NHS referral. This involves an online clinical assessment, and if approved, a prescription is issued and dispensed by a GPhC-registered pharmacy. Private prescriptions typically cost between £129–£320 per month depending on dose.
Both routes require that you meet eligibility criteria and have a clinical assessment to ensure Mounjaro is appropriate for your individual health.
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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.
Mounjaro Eligibility and the Prescription Process
To be prescribed Mounjaro, you must meet specific criteria. Adults with a BMI of 30 kg/m² or above are generally eligible, or BMI 27–29.9 kg/m² if you have weight-related health conditions such as type 2 diabetes, prediabetes, high blood pressure, abnormal blood fats, sleep apnoea, or cardiovascular disease.
Lower BMI thresholds apply for adults of South Asian, Chinese, Black African, or Black Caribbean heritage due to increased health risks at lower weights.
A prescriber will assess your medical history, current medications, and suitability before issuing a prescription. You'll start on the lowest dose (2.5 mg once weekly) and increase gradually over 16+ weeks, with a maximum dose of 15 mg weekly. Use our free GLP-1 weight loss calculator to explore potential results at different doses, and the BMI calculator to check your current BMI against NHS thresholds.
- 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 my GP prescribe Mounjaro directly from their surgery?
Not typically. Mounjaro through the NHS is prescribed by specialist tier 3 weight management services, not primary care. Your GP can discuss referral options and help you access specialist services, but they cannot dispense Mounjaro from the surgery. Private online prescribers can issue prescriptions without NHS referral.
How long does it take to get a Mounjaro prescription on the NHS?
Timescales vary significantly by region and service availability. Some areas have waiting lists of several months to over a year. Others have limited capacity. Ask your GP about local waiting times and whether there are alternative options in your area.
What happens if I don't meet NHS eligibility criteria?
If you don't meet NHS criteria, private prescription access remains available. You can have an online clinical assessment with a UK-licensed prescriber. They will assess your individual circumstances and decide whether Mounjaro is appropriate for you. Private assessments may be more flexible than NHS thresholds.
Can I switch from private Mounjaro to NHS Mounjaro?
In theory yes, but in practice this is complicated. You would need to be referred to an NHS specialist service, meet their criteria, and be accepted. Waiting times and availability vary. Discuss this with your GP if you're considering a switch.
Do I need to be referred by my GP to get a private Mounjaro prescription?
No. Private prescriptions do not require a GP referral. You can access a UK-licensed prescriber directly through an online consultation. However, informing your GP that you're using Mounjaro is advisable so they can monitor your health and manage any other medications appropriately.
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.