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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Can GPs Prescribe Mounjaro in the UK?
In short: GPs cannot routinely prescribe Mounjaro (tirzepatide) on the NHS. Instead, Mounjaro is prescribed through specialist tier 3 weight management services following NHS NICE approval. However, it is available privately through UK-licensed online prescribers following a clinical assessment. This guide explains the NHS pathway, eligibility criteria, and how to access Mounjaro both through the NHS and private routes in the UK.
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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 Pathway for Mounjaro in the UK
Mounjaro is not routinely available from GPs. NICE has approved tirzepatide (Mounjaro) for use within NHS specialist weight management services, but it is only prescribed by tier 3 or tier 4 specialist services—not by GPs in primary care. To access Mounjaro through the NHS, you must first be referred by your GP to a tier 3 specialist weight management service in your region.
Tier 3 services typically require:
- Initial assessment by a GP (who refers you to specialist services)
- Specialist multidisciplinary assessment at tier 3 (including dietitian, exercise specialist, and clinician)
- Evidence of previous weight management attempts
- BMI of 30 or above, or 27–29.9 with weight-related health conditions
- For South Asian, Chinese, Black African, or Black Caribbean adults, lower BMI thresholds may apply
Once approved by the specialist team, your GP may then support monitoring your progress, but the initial prescription and dose titration come from the tier 3 service. NHS availability varies significantly by region, and waiting lists can be lengthy—sometimes 12 months or longer in some areas.
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.
Private GP Prescribing and NHS vs Private Access
If you cannot access Mounjaro through the NHS or face long waiting lists, Mounjaro is available privately through GPhC-registered online pharmacies following an assessment by a UK-licensed prescriber. Private prescribers can assess your eligibility based on similar criteria (BMI 30+, or 27+ with comorbidities) and issue a prescription if appropriate.
NHS vs private comparison: NHS access is free but typically delayed; private access is faster but costs approximately £129–£320 per month depending on dose. Use our free GLP-1 weight loss calculator to estimate potential outcomes, and the BMI calculator to confirm your current status against NHS eligibility thresholds.
To check if you're eligible for either route, calculate your BMI using our free calculator and note any weight-related health conditions (type 2 diabetes, prediabetes, high blood pressure, sleep apnoea, cardiovascular disease). If your BMI is 30 or above, or 27–29.9 with one of these conditions, you may be eligible. Your next step is a conversation with your GP about NHS specialist referral or exploring private prescribing options.
- 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 on the NHS?
No, GPs cannot routinely prescribe Mounjaro on the NHS. It is only prescribed by tier 3 specialist weight management services. Your GP can refer you to these services, and the specialist team will assess and prescribe if appropriate.
What is a tier 3 weight management service?
Tier 3 services are NHS specialist multidisciplinary weight management teams that include dietitians, exercise specialists, and clinicians. They provide intensive assessment and support, and can prescribe weight loss medications like Mounjaro as part of a comprehensive programme.
How long does the NHS referral process take?
This varies by region (ICB area). Some services have waiting lists of 6–12 months or longer. You should ask your GP for current waiting times in your local area when requesting a referral.
Can I get Mounjaro through a private GP without NHS referral?
Yes, Mounjaro is available privately through UK-licensed online prescribers. You would have an online clinical assessment, and if you meet eligibility criteria, a prescription can be issued and dispensed by a GPhC-registered pharmacy.
What eligibility criteria do I need for Mounjaro on the NHS?
NHS eligibility typically requires BMI of 30 or above, or 27–29.9 with at least one weight-related health condition (type 2 diabetes, prediabetes, high blood pressure, sleep apnoea, or cardiovascular disease). Lower thresholds apply for South Asian, Chinese, Black African, and Black Caribbean adults.
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.