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
Can Anyone Get Mounjaro? UK Eligibility Explained
No, not everyone can get Mounjaro in the UK. Access to this prescription-only weight management injection depends on specific health criteria set by NICE and your prescriber. Both Mounjaro (tirzepatide) and Wegovy (semaglutide) have similar eligibility requirements, though they work differently. Your GP or a licensed prescriber will assess whether either medication is suitable for you based on your BMI, health conditions, and overall health profile. Understanding eligibility is the first step towards exploring whether prescription weight loss treatment might help support your weight management journey.
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.
Mounjaro vs Wegovy — Eligibility and Mechanism Differences
Eligibility is the same for both medications: You may be eligible for Mounjaro or Wegovy if you have a BMI of 30 kg/m² or above, or a BMI of 27–29.9 kg/m² with at least one weight-related health condition (such as type 2 diabetes, high blood pressure, or cardiovascular disease). For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower thresholds apply (BMI 27.5 or above).
How they differ: Mounjaro is a dual GIP and GLP-1 receptor agonist, meaning it activates two hormone pathways in the body. Wegovy is a GLP-1 receptor agonist only. Clinical trial data from SURMOUNT-1 (Mounjaro) showed average weight loss of approximately 15–21% body weight, whilst STEP-1 (Wegovy) showed approximately 15% average weight loss. Both results were achieved alongside reduced-calorie diet and increased physical activity — individual outcomes vary significantly.
The choice between them depends on your prescriber's clinical judgment, your health profile, and personal factors. Neither medication assures weight loss, and both require ongoing monitoring.
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 Access Mounjaro or Wegovy — Important Restrictions
You will not be eligible if you:
- Are under 18 years of age
- Are pregnant, planning to become pregnant, or breastfeeding
- Have a history of severe gastroparesis or serious digestion problems
- Have a personal or family history of medullary thyroid cancer
- Have multiple endocrine neoplasia syndrome type 2 (MEN2)
- Are allergic to tirzepatide (Mounjaro) or semaglutide (Wegovy)
Additionally, if you take certain medications — particularly sulphonylureas or insulin for diabetes — your prescriber may need to adjust doses or recommend an alternative. Use our free BMI calculator to check your current BMI and assess whether you might meet the initial criteria, then discuss options with your GP or a licensed prescriber who can provide personalised advice.
- 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 get Mounjaro or Wegovy?
You generally need a BMI of 30 or above, or 27–29.9 with weight-related health conditions. For South Asian, Chinese, Black African, or Black Caribbean adults, eligibility may start at BMI 27.5 or above due to higher health risks at lower weights. Your prescriber will assess your individual circumstances.
Can I get Mounjaro or Wegovy on the NHS?
Both are available on the NHS through specialist tier 3 weight management services, but access is limited and varies significantly by region. Waiting lists can be lengthy. Private access is available through GPhC-registered online pharmacies following a clinical assessment — no NHS referral needed.
Is Mounjaro better than Wegovy?
Both are effective for weight management. Mounjaro (dual mechanism) showed slightly higher average weight loss in trials, but results vary by individual. Your prescriber will recommend the most suitable option based on your health profile, medical history, and any other medications you take.
What happens if I have type 2 diabetes — can I get Mounjaro?
Yes. Type 2 diabetes or prediabetes is a weight-related condition that may make you eligible for prescription weight loss treatment even at a lower BMI. However, if you're already taking insulin or certain diabetes medications, your prescriber must carefully assess dosing interactions before prescribing.
Can I switch from Wegovy to Mounjaro or vice versa?
Some people do switch between them, but this must be managed by your prescriber. There is no official conversion chart — your prescriber will assess the appropriate starting dose for whichever medication is recommended. Never switch medications without professional guidance.
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.