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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Mounjaro Criteria for UK Adults
If you're considering Mounjaro (tirzepatide) in the UK, understanding the eligibility criteria is the first step. Mounjaro is a prescription-only weight management injection licensed in the UK, but not everyone meets the criteria for prescription. Access depends on your BMI, health conditions, and whether you're pursuing NHS or private prescription. This guide explains who qualifies and how to access it through each route.
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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.
Mounjaro Eligibility Criteria in the UK
UK-licensed Mounjaro eligibility requires one of the following:
- BMI of 30 kg/m² or above (obesity), OR
- BMI of 27–29.9 kg/m² (overweight) with at least one weight-related health condition
If you're of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds — you may be eligible from BMI 27.5 or above because these groups face higher health risks at lower weights.
Weight-related health conditions that may qualify: type 2 diabetes or prediabetes, high blood pressure, abnormal blood fats, obstructive sleep apnoea, or history of heart attack or stroke. Use our free BMI calculator above to check your BMI instantly and see which category you fall into.
You cannot take Mounjaro if you are under 18, pregnant, breastfeeding, or allergic to tirzepatide. A licensed prescriber will assess your full medical history before prescribing.
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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: Referral to a tier 3 specialist weight management service through your GP. NICE has approved tirzepatide for NHS use, but access varies significantly by region and availability. Waiting times can be months or longer in many areas. Your GP can refer you if you meet criteria, though not all ICBs currently fund Mounjaro widely.
Private route: Online consultation with a UK-licensed prescriber via GPhC-registered services. No GP referral needed. If approved, the prescription is dispensed by a registered pharmacy. Private prescriptions typically cost between £180–£320 per month depending on your dose — higher doses cost more. Try our GLP-1 weight loss calculator to project potential outcomes at different doses.
Both routes require a clinical assessment to confirm you're suitable for tirzepatide treatment.
- 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's the minimum BMI to get Mounjaro on the NHS in the UK?
The minimum BMI for NHS Mounjaro is 30 kg/m² without health conditions, or 27–29.9 kg/m² if you have a weight-related condition like diabetes or high blood pressure. If you're of South Asian, Chinese, Black African, or Black Caribbean heritage, lower thresholds apply from BMI 27.5. Check your BMI using our free calculator above.
Can I get Mounjaro privately without seeing my GP?
Yes. Private prescribers offering online consultations can assess you and issue a prescription directly, without involving your GP. You'll need a consultation with a UK-licensed prescriber, and if approved, the prescription is dispensed by a GPhC-registered pharmacy. Private access is faster but involves out-of-pocket costs.
How much does private Mounjaro cost in the UK?
Private Mounjaro typically costs £180–£320 per month depending on your dose. Starting doses (2.5 mg) are usually cheaper; maximum dose (15 mg) is most expensive. Each KwikPen contains 4 weekly injections. Prices vary by provider, so compare options. Ask about batch discounts if committing to multiple months.
How long are NHS waiting lists for Mounjaro?
NHS waiting times vary dramatically by region and local ICB funding. Some areas have waits of 6–12 months; others have longer delays or limited availability. Contact your local tier 3 weight management service for current waiting times. Private prescription offers faster access if NHS waiting times are long in your area.
What happens if I don't meet the BMI criteria for Mounjaro?
If you're slightly below the BMI threshold, your GP can discuss other tier 2 interventions like structured weight management programmes, digital tools (like our BMI calculator and progress tracker), or dietary support. If you have underlying health conditions, your GP may prioritise you for specialist referral despite lower BMI.
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.