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
Free tracker included with every download this week
Who Can Take Mounjaro? UK Eligibility Criteria
Mounjaro (tirzepatide) is a prescription-only weight management injection available in the UK, but not everyone qualifies. Your eligibility depends on your BMI, age, and whether you have weight-related health conditions. This guide explains the exact criteria NHS specialists and private prescribers use to assess whether Mounjaro is suitable for you. Understanding these thresholds will help you know whether to discuss this option with your GP or a licensed prescriber.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
UK Eligibility Thresholds for Mounjaro
To be eligible for Mounjaro in the UK, you must meet specific BMI and health criteria:
- BMI of 30 kg/m² or above (obese category), OR
- BMI of 27–29.9 kg/m² (overweight) plus at least one weight-related health condition
Weight-related conditions that may qualify include type 2 diabetes or prediabetes, high blood pressure, abnormal blood fats (dyslipidaemia), obstructive sleep apnoea, or a history of heart attack or stroke. If you're of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds may apply — eligibility may start at BMI 27.5 or above, as these groups face higher health risks at lower BMI levels according to NHS guidance. Use our free BMI calculator above to check your current BMI instantly. Your prescriber will also assess whether you have any conditions that make Mounjaro unsuitable.
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.
Who Cannot Take Mounjaro
Mounjaro is not suitable for: under-18s, anyone pregnant or planning pregnancy, those breastfeeding, and people with a known allergy to tirzepatide or any ingredients. You may not be eligible if you have severe gastroparesis or serious digestion problems. If you take other medications, particularly oral contraceptives or diabetes medications (sulphonylureas or insulin), your prescriber needs to assess suitability and may adjust doses. Always inform your GP or prescriber of your complete medical history and all medications before starting Mounjaro. Your healthcare professional will use the GLP-1 weight loss calculator concept alongside clinical guidelines to determine if this medication is right for you.
- 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 BMI do I need to be eligible for Mounjaro in the UK?
You qualify if your BMI is 30 or above, or 27–29.9 with a weight-related health condition like type 2 diabetes, high blood pressure, or sleep apnoea. Lower thresholds (from BMI 27.5) apply for South Asian, Chinese, Black African, or Black Caribbean adults. Use our BMI calculator to check yours.
Can I get Mounjaro on the NHS in the UK?
Yes, Mounjaro (tirzepatide) is approved by NICE for NHS specialist weight management services. However, NHS access is through tier 3/4 specialist services, not standard GP prescriptions, and availability varies significantly by region with potential waiting lists. Private prescribing offers faster access.
What is the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, while Wegovy (semaglutide) activates GLP-1 alone. Both are prescription-only weight loss injections licensed in the UK. Mounjaro typically starts at 2.5 mg weekly, maximum 15 mg. Wegovy starts at 0.25 mg, maximum 2.4 mg. Clinical trial results and side effects differ slightly between the two.
Will my GP prescribe Mounjaro directly?
Standard NHS GP practice does not typically prescribe Mounjaro for weight management—it's initiated through specialist tier 3/4 weight management services following referral. Private GPhC-registered online prescribers can assess and prescribe Mounjaro following an online clinical consultation if you meet eligibility criteria.
What happens during a Mounjaro dose titration?
Dose titration means gradually increasing your dose every four weeks until reaching an effective maintenance level. You start at 2.5 mg weekly, then increase to 5 mg, 7.5 mg, 10 mg, 12.5 mg, and finally 15 mg (the maximum). Your prescriber may adjust this based on your response and any side effects you experience.
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.