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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Using Mounjaro Pen in the UK — Cost and Access Guide
Mounjaro (tirzepatide) is a prescription-only weight management injection available in the UK via the pre-filled KwikPen device. The cost and how you access it depends on whether you go through the NHS or a private route. This guide explains both pathways, what to expect, and how much Mounjaro typically costs in the UK, so you can understand your options before speaking to your GP or a licensed prescriber.
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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.
NHS vs Private Access — Where to Get Mounjaro in the UK
NHS access: Mounjaro is approved by NICE for use within NHS specialist weight management services. However, it is not routinely available through standard GP prescriptions. You typically need referral to a tier 3 specialist weight management service through your GP. Availability varies significantly by region and ICB (Integrated Care Board), and waiting lists can be several months to over a year in many areas.
Private access: Mounjaro is available through GPhC-registered online pharmacies following an online clinical assessment with a UK-licensed prescriber. This route does not require NHS referral and is often faster than NHS services. You will need to complete a health questionnaire, and a prescriber will assess whether the Mounjaro KwikPen is suitable for you before issuing a prescription.
Cost context: Private Mounjaro costs typically range from £150 to £300+ per month depending on your dose (2.5 mg to 15 mg) and the provider. This covers the prescription assessment and the KwikPen itself. NHS provision is free at the point of use but availability is limited.
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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.
The Online Prescription Process and What to Expect
If you choose private prescription, the process is straightforward: complete an online health form covering your weight, medical history, medications, and any contraindications, then a UK-licensed prescriber will review your information. If approved, you will receive a prescription that a GPhC-registered pharmacy dispenses as a pre-filled KwikPen. You can start on the lowest dose (2.5 mg) and increase gradually every 4 weeks under guidance. Many private services offer follow-up support, though this varies by provider. Always check that the pharmacy is GPhC-registered and the prescriber is a qualified UK healthcare professional. If you have existing health conditions, diabetes, or are taking other medications, your GP may still be worth consulting to ensure safety, even if using the private route.
- 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.
How much does Mounjaro cost privately in the UK?
Private Mounjaro typically costs between £150 and £300+ per month, depending on your dose. The 2.5 mg starting dose is usually at the lower end, while the 15 mg maximum dose may be higher. Prices vary between providers, so it's worth comparing. This includes the online clinical assessment and the KwikPen itself.
Can I get Mounjaro free on the NHS?
Yes, Mounjaro is available free through NHS specialist weight management services, but availability is limited and varies by region. You'll need GP referral to a tier 3 service, and waiting lists can be very long. Ask your GP about local availability and whether you meet the eligibility criteria for NHS-funded treatment.
What is a Mounjaro KwikPen exactly?
A KwikPen is a pre-filled, single-use injection pen that delivers one weekly dose of Mounjaro. Each pen contains one 4-week dose (4 individual injections). You inject once weekly into your stomach, thigh, or upper arm. Each KwikPen is colour-coded by dose strength and is simple to use with a button mechanism.
How long does a Mounjaro prescription take to arrive?
Private prescriptions are typically processed within 2–5 working days. The pharmacy will post your KwikPens, which usually arrives within 3–7 days. NHS referral can take months depending on your local service. Private routes are generally faster if you meet eligibility criteria.
Do I need to see my GP before using Mounjaro privately?
Not strictly required, as the online prescriber will assess you. However, if you have existing health conditions like diabetes, heart disease, or take multiple medications, informing your GP is advisable for safety. Your GP may also help monitor your progress and manage any interactions with other treatments.
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.