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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Injecting Mounjaro in Your Thigh — UK Cost & Access
Injecting Mounjaro in your thigh is one of three approved injection sites and is often the easiest option for self-administration. Mounjaro (tirzepatide) is a prescription-only, once-weekly weight management injection available in the UK through both NHS specialist services and private prescription routes. If you're considering Mounjaro, understanding injection technique, cost, and how to access it is important. This guide covers UK-specific information on administration, pricing, and the pathways to getting a prescription.
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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.
UK Access Routes and Cost Context for Mounjaro
Mounjaro is available in the UK through two main routes: NHS specialist weight management services and private prescription from a UK-licensed prescriber. On the NHS, access is through tier 3 or 4 specialist weight management services — typically following a GP referral. NHS availability varies significantly by region and ICB, with some areas having substantial waiting lists. Privately, Mounjaro is available without NHS referral. UK private prescription costs range from approximately £129 to £320 per month, depending on the dose you're prescribed and the provider. These costs cover the prescription assessment, prescription itself, and the KwikPen (which contains 4 weeks of injections). Higher doses (12.5 mg and 15 mg) typically cost more than lower starting doses (2.5 mg and 5 mg). Our GLP-1 weight loss calculator can help you understand potential outcomes at different doses, which may inform your discussions with a prescriber about which dose pathway suits your health goals.
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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.
Injection Technique and Getting a UK Prescription
The thigh is an ideal injection site — you can inject into the front or outer part of your thigh, rotating sites each week to prevent skin irritation. Each Mounjaro KwikPen contains 4 pre-filled doses (4 weeks' supply). The pen is easy to use: clean the skin, pinch the area, insert the needle at 90 degrees, press the button, and hold for 3 seconds. To get a prescription in the UK privately, you'll have an online consultation with a UK-licensed prescriber who will assess your BMI, health history, and eligibility based on NICE guidance. If approved, your prescription is sent to a GPhC-registered pharmacy and the KwikPen is dispatched to your address. NHS access requires GP referral and specialist assessment, though waiting times vary widely by region. Always store unopened pens in the fridge (2–8°C) and can keep opened pens at room temperature for up to 30 days after first use.
- 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 are the three approved injection sites for Mounjaro?
The three approved sites are your stomach (abdomen), upper thigh, and upper arm. The thigh is popular because it's easy to access and self-administer. You should rotate your injection site each week to prevent irritation or lumps forming under the skin.
How much does Mounjaro cost privately in the UK?
Private prescription costs typically range from £129 to £320 per month, depending on dose. A single KwikPen (4 weeks of injections) costs more at higher doses like 15 mg tirzepatide compared to starting doses like 2.5 mg. Costs vary between private providers.
Can I get Mounjaro on the NHS in the UK?
Yes, Mounjaro is approved by NICE for NHS use in specialist tier 3 and 4 weight management services. However, access requires a GP referral and assessment by a specialist team. Availability and waiting times vary significantly depending on your region and local ICB commissioning decisions.
What's the difference between accessing Mounjaro via NHS versus private prescription?
NHS access is free at point of use but requires referral, specialist assessment, and often involves waiting lists. Private access is faster (typically within days) and doesn't require NHS referral, but you pay the full cost. Both routes require a clinical assessment to confirm eligibility.
How do I know if I'm eligible for Mounjaro in the UK?
Generally, you may be eligible if you have a BMI of 30 or above, or 27 or above with weight-related health conditions like type 2 diabetes or high blood pressure. A GP or licensed prescriber can assess your individual eligibility based on NICE guidance and your personal health circumstances.
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.