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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Getting Mounjaro Through Your GP and the NHS
Mounjaro (tirzepatide) is now approved by NICE for weight management in the UK, but accessing it through your NHS GP is different from private prescribing. You cannot request Mounjaro directly from your standard GP practice — instead, you need referral to a specialist tier 3 weight management service. This guide explains NHS eligibility, how the referral pathway works, and what the clinical evidence shows about Mounjaro's effectiveness. Use our free BMI calculator above to check your starting point, then understand your NHS options for weight loss support.
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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 Eligibility and the Tier 3 Referral Pathway
NHS eligibility for Mounjaro (tirzepatide) requires:
- BMI of 30 kg/m² or above, or BMI 27–29.9 with weight-related health conditions (type 2 diabetes, hypertension, sleep apnoea, cardiovascular disease)
- For South Asian, Black African, or Black Caribbean adults: lower thresholds apply (BMI 27.5 or above)
- Commitment to lifestyle changes (diet and physical activity) alongside medication
Access is through tier 3 specialist weight management services, not standard GP practices. Your GP must refer you to your local NHS integrated care board (ICB) weight management team. NICE approved tirzepatide in 2024 for use within NHS specialist services. However, availability varies significantly by region — some areas have waiting lists of 12 months or longer. The KwikPen device delivers doses from 2.5 mg up to 15 mg weekly, with clinical trials showing average weight loss of 15–21% body weight when combined with reduced-calorie diet and physical activity.
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 Routes for Mounjaro in the UK
Two distinct pathways exist for accessing Mounjaro in the UK. The NHS route involves GP referral to tier 3 services, requires no upfront cost, but has significant waiting times and regional availability issues. The private route offers faster access through online consultations with UK-licensed prescribers, bypassing NHS waiting lists, but costs approximately £129–£320 per month depending on dose. Both routes require clinical assessment to confirm you meet eligibility criteria — a prescriber will review your medical history, current medications, and weight-related health conditions. Neither route assures prescription; individual assessment determines suitability. Try our GLP-1 weight loss calculator to project potential outcomes and understand whether Mounjaro fits your weight management goals.
- 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 ask my GP for Mounjaro directly?
No. Your GP cannot prescribe Mounjaro in standard practice. You must be referred to a specialist tier 3 weight management service through your local NHS integrated care board. Ask your GP for a referral if you meet eligibility criteria (BMI ≥30, or BMI 27–29.9 with weight-related health conditions).
How long is the NHS waiting list for Mounjaro?
Waiting times vary by region. Some areas have waiting lists of 6–12 months or longer due to high demand and limited tier 3 service capacity. Contact your local ICB weight management service for current waiting times in your area.
What is MHRA approval for Mounjaro in the UK?
Mounjaro (tirzepatide) has MHRA approval for weight management in adults. It carries Black Triangle (▼) status, meaning it is subject to additional monitoring for safety. NICE also reviewed and approved it for NHS use within specialist weight management services in 2024.
Is Mounjaro cheaper through the NHS or private prescribing?
Through the NHS, there is no medication cost once you access tier 3 services. Private prescribing costs £129–£320 per month depending on dose. However, NHS access requires meeting referral criteria and enduring waiting lists, while private access is faster but costs money.
What happens if I'm not eligible for NHS Mounjaro?
If you don't meet NHS tier 3 eligibility (BMI ≥30 with no weight-related conditions, or lower BMI thresholds for certain ethnic groups), you cannot access Mounjaro through standard NHS services. You may explore private prescribing routes, or discuss alternative weight management support with your GP such as behavioural programmes or Tier 2 services.
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.