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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How Much Is Mounjaro on NHS vs Wegovy?
Mounjaro (tirzepatide) and Wegovy (semaglutide) are both prescription-only weight loss injections available in the UK, but accessing them through the NHS works differently from private prescribing. The cost to you depends on whether you're eligible for NHS funding or choosing private treatment. This guide explains the costs, eligibility criteria, and how to access each medication through the NHS or privately.
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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 Access, Costs, and Clinical Differences
On the NHS: Neither Mounjaro nor Wegovy are typically free prescriptions for weight management alone. Access is through NHS specialist tier 3 or 4 weight management services, not standard GP prescription. Availability varies significantly by region and ICB (Integrated Care Board). Waiting lists in many areas are substantial — sometimes months or years. Your GP can refer you to your local specialist weight management service, but acceptance depends on NHS eligibility criteria and local capacity.
Clinical differences: Mounjaro is a dual GIP and GLP-1 receptor agonist, meaning it works through two hormone pathways simultaneously. Wegovy is a GLP-1 receptor agonist only, activating a single pathway. Clinical trials (SURMOUNT for Mounjaro, STEP for Wegovy) showed average weight loss of approximately 15–21% for Mounjaro and 15% for Wegovy, though individual results vary significantly. Both require a reduced-calorie diet and increased physical activity to work effectively.
- Mounjaro: once-weekly injection, doses from 2.5 mg to 15 mg
- Wegovy: once-weekly injection, doses from 0.25 mg to 2.4 mg
- Both require gradual dose escalation over weeks
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.
Eligibility and Which Medication Suits You
NHS eligibility for both: You may qualify for NHS specialist assessment if you have a BMI of 30 kg/m² or above, or 27–29.9 kg/m² with at least one weight-related health condition (type 2 diabetes, prediabetes, high blood pressure, abnormal blood fats, sleep apnoea, or cardiovascular disease). South Asian, Chinese, Black African, and Black Caribbean adults may qualify at lower BMI thresholds (from 27.5 kg/m²) due to higher cardiovascular risk at lower weights.
Which medication is prescribed depends on your individual health profile, prescriber preference, and regional availability. Your GP and specialist can assess which is most suitable. Both are prescription-only medicines requiring a clinical assessment before being prescribed. Try our free BMI calculator above to check where you stand, and use our GLP-1 weight loss calculator to estimate potential outcomes with either medication.
Private prescribing offers faster access: both medications are available from GPhC-registered online pharmacies following an online clinical assessment with a UK-licensed prescriber. Private costs range from approximately £129–£320 per month depending on dose and provider. Private prescribers can sometimes prescribe at lower BMI thresholds than NHS services, offering an alternative if NHS waiting lists are long or you don't meet local NHS criteria. However, both NHS and private routes require a proper clinical assessment — neither medication should be self-prescribed or obtained without professional review of your health.
- 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 get Mounjaro or Wegovy free on the NHS?
Access depends on your local NHS service. Both are available through NHS tier 3/4 specialist weight management services, but availability, waiting times, and eligibility vary significantly by region. You'll need a GP referral to your local specialist service. If you don't meet local NHS criteria or face long waiting lists, private prescribing offers faster access — though you'll pay for the medication yourself.
What's the difference between Mounjaro (tirzepatide) and Wegovy (semaglutide)?
Mounjaro is a dual GIP and GLP-1 agonist (two hormone pathways), while Wegovy is a GLP-1 agonist only (single pathway). Clinical trials showed Mounjaro achieved average weight loss of 15–21% and Wegovy approximately 15%, though results vary individually. Both require diet and exercise changes. Your prescriber will assess which is more suitable for your health profile.
How do I access Mounjaro or Wegovy on the NHS?
Ask your GP to refer you to your local NHS specialist weight management service (tier 3 or 4). You'll be assessed against NHS eligibility criteria (BMI 30+ or 27+ with weight-related conditions). Private access is faster: online prescribing through GPhC-registered pharmacies costs £129–£320/month depending on dose. Both routes require a clinical assessment before prescription.
What qualifies as a weight-related health condition for NHS access?
Type 2 diabetes, prediabetes, high blood pressure, abnormal blood fats, obstructive sleep apnoea, and cardiovascular disease (history of heart attack or stroke) are recognised weight-related conditions. If you have any of these plus a BMI of 27–29.9, you may qualify for NHS assessment. South Asian, Chinese, Black African, or Black Caribbean adults may qualify from BMI 27.5 with these conditions.
How quickly can I start Mounjaro or Wegovy if I go private?
Private prescribing is typically faster than NHS: you can usually have a consultation within days and medication within 1–2 weeks of prescription. NHS waiting times vary greatly by region — some areas have waiting lists of several months or longer. Use our GLP-1 weight loss calculator to explore potential outcomes and discuss options with your GP or a private prescriber to find the right route for you.
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.