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 I Use Mounjaro in the UK?
Whether you can use Mounjaro (tirzepatide) in the UK depends on your BMI, health conditions, and whether you access it through the NHS or privately. NICE has approved tirzepatide for use in NHS specialist weight management services, but eligibility and access vary significantly by region. This guide explains NHS criteria, how the KwikPen delivery system works, and the different routes to getting Mounjaro in the UK. Use our free BMI calculator above to check your starting point, and read on to understand your options.
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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 Criteria for Mounjaro in the UK
The NHS approves Mounjaro for adults who meet specific BMI and health criteria. You may be eligible if you have a BMI of 30 or above, or a BMI of 27–29.9 with at least one weight-related health condition such as type 2 diabetes, prediabetes, high blood pressure, abnormal cholesterol, obstructive sleep apnoea, or cardiovascular disease history.
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds: BMI 27.5 or above may qualify, as these groups face higher metabolic health risks at lower BMI levels.
You cannot access Mounjaro on the NHS if you are under 18, pregnant, breastfeeding, or have a severe allergy to tirzepatide. Access is through NHS tier 3 specialist weight management services, not routine GP prescription. Your GP can refer you, but waiting times vary from weeks to years depending on your region. During assessment, prescribers will evaluate your full health picture, medications, and suitability for the KwikPen injection device before approval.
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 Access: How to Get Mounjaro in the UK
NHS route: Requires referral from your GP to a specialist tier 3 weight management service. Once referred, the service conducts a clinical assessment and prescribes Mounjaro if eligible. The NHS covers the cost, but availability is limited and waiting lists can be lengthy in many areas. Check your Integrated Care Board (ICB) website to understand local access.
Private route: Available through GPhC-registered online prescribers without an NHS referral. You complete an online health questionnaire, receive a clinical assessment from a UK-licensed prescriber, and collect your prescription from a pharmacy. Private Mounjaro costs range from approximately £120–£280 per month depending on dose. Both routes provide the same medication in the same KwikPen format with identical dose titration schedules.
- 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 starting dose of Mounjaro on the NHS?
The NHS standard starting dose is 2.5 mg once weekly for the first 4 weeks. You then increase to 5 mg for the next 4 weeks, with further increases up to 15 mg if tolerated. Dose increases happen at minimum 4-week intervals. Your prescriber will tailor timing based on side effects and response.
Can I compare my eligibility using a BMI chart?
Yes — use our free BMI calculator on this page to calculate your BMI instantly using your height and weight. Then compare your result against the NHS categories: healthy 18.5–24.9, overweight 25–29.9, obese 30+. If you're of South Asian or Black African heritage, lower thresholds apply (healthy up to 22.9, overweight 23–27.4, obese 27.5+).
How long does it take to get Mounjaro on the NHS?
Wait times vary by region. Some areas offer assessment within weeks; others have 6–12 month waiting lists. Contact your GP or local ICB to find out your area's current pathway and expected timescale. Private prescribing is typically faster, with assessment and prescription possible within days.
What happens if my BMI is just below 30 but I have health conditions?
If your BMI is 27–29.9, you may still qualify for Mounjaro on the NHS if you have a weight-related health condition like type 2 diabetes, hypertension, or sleep apnoea. The prescriber will assess your overall health risk, not BMI alone. Your GP can discuss which conditions strengthen your case.
Is Mounjaro the same as Ozempic or Wegovy?
No. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist — different from Wegovy (semaglutide), which is a GLP-1-only medication. Both are licensed for weight management in the UK, but they work via different mechanisms. Your prescriber will assess which suits your health profile best.
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.