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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Where Is The Cheapest Mounjaro in the UK?
Mounjaro and Wegovy are both prescription-only weight loss injections available in the UK, but costs vary significantly depending on whether you access them through the NHS or private prescription. There's no single "cheapest" option—cost depends on your eligibility, dose, and which route you choose. This guide explains the pricing differences between Mounjaro (tirzepatide) and Wegovy (semaglutide), so you can understand what to expect and find the most affordable option for your situation.
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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: Cost and Mechanism Comparison
Both medications work differently and have different pricing structures. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, available as pre-filled KwikPen devices injected once weekly. Wegovy (semaglutide) is a GLP-1 agonist only, also injected once weekly. In clinical trials, Mounjaro showed average weight loss of 15–21% of body weight, whilst Wegovy showed approximately 14.9% average loss—though individual results vary significantly. Private prescription costs range from approximately £129–£320 per month depending on dose and provider, with Mounjaro kwikpen doses from 2.5mg to 15mg and Wegovy doses from 0.25mg to 2.4mg. NHS access through specialist weight management services is free, but availability varies by region and waiting lists can be lengthy.
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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: Finding Affordable Access
The cheapest option is NHS provision if you can access it—specialist weight management services prescribed through the NHS are completely free. However, NHS access requires referral from your GP to a tier 3 specialist service and varies significantly by region. Some areas have substantial waiting lists (months to years in some cases). Private prescription through GPhC-registered online pharmacies typically costs £129–£320 monthly depending on dose. To access either route, you must first have a clinical assessment from a UK-licensed prescriber who will evaluate your BMI, health conditions, and suitability. Use our free BMI calculator to check your current BMI and understand your starting point before consulting a prescriber.
- 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.
Is Mounjaro cheaper than Wegovy in the UK?
Not necessarily. Both medications cost similarly in private prescription (around £129–£320/month depending on dose). The cheapest option for either is NHS provision, which is free but requires specialist referral and varies by region. Your prescriber will assess which medication suits you based on your health, not cost alone.
Can I get Mounjaro on the NHS?
Yes, Mounjaro (tirzepatide) is approved for NHS use through specialist tier 3 weight management services. However, access varies significantly by region and local integrated care boards. You need a GP referral and clinical assessment. Waiting times can be several months to over a year depending on your area.
What does a Mounjaro KwikPen cost privately?
A single KwikPen (4-week supply at your current dose) typically costs £130–£320 privately, depending on the dose, provider, and whether you're starting, titrating, or on maintenance. Higher doses cost more. Prices vary between private prescribing services, so comparing options is worthwhile.
How do I get the cheapest option—NHS or private?
Check NHS availability first by asking your GP about referral to your local specialist weight management service (it's free). If waiting lists are prohibitive or you don't meet local criteria, private prescription is your alternative. Our GLP-1 weight loss calculator can help you understand potential outcomes at different doses, which may inform your decision.
Is one medication cheaper than the other for weight loss results?
Both show similar average weight loss (15–21% for Mounjaro, ~15% for Wegovy), so cost-per-kilogram-lost is comparable. Your prescriber decides suitability based on your health profile, not cost. Individual results vary significantly, so "cheaper" doesn't necessarily mean better value for your specific outcome.
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.