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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Mounjaro Pen Injection: UK Cost and Access Guide
Mounjaro (tirzepatide) is a prescription-only weekly weight loss injection available through both NHS and private routes in the UK. Access and cost vary significantly depending on whether you pursue NHS specialist services or private prescription. This guide explains the different pathways, typical costs, and what to expect from each route. Understanding your options helps you make an informed decision about whether this medication is suitable for your circumstances.
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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.
Private Prescription Costs and Access in the UK
Private prescription costs for Mounjaro typically range from £150 to £320 per month in the UK, depending on the dose and the provider. Starting doses (2.5 mg) are generally cheaper than maximum doses (15 mg). Each KwikPen contains four weekly injections, so monthly cost reflects a four-week supply.
- Starting dose (2.5 mg): approximately £150–£180 per month
- Mid-range doses (5–10 mg): approximately £200–£260 per month
- Maximum dose (15 mg): approximately £280–£320 per month
Private access does not require an NHS referral. You can obtain a prescription from a UK-licensed prescriber through an online consultation following a clinical assessment. This weekly weight loss injection can be dispensed by a registered pharmacy and delivered to your home. Costs are your responsibility — private prescriptions are not covered by the NHS. Some people use a weight loss calculator to estimate potential outcomes before committing to treatment.
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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.
NHS Access vs Private Route: What You Need to Know
NHS access to Mounjaro is through specialist tier 3/4 weight management services, not standard GP prescriptions. You must be referred by your GP and assessed by a specialist team. NICE has approved tirzepatide for NHS use, but regional availability varies significantly — waiting lists in some areas exceed 12–18 months. Your prescriber will conduct a full health assessment before starting this KwikPen injection.
Private route advantage: faster access without waiting lists. You complete an online clinical assessment with a UK-licensed prescriber, and if approved, receive a prescription to take to a GPhC-registered pharmacy. The entire process typically takes 5–10 working days from consultation to delivery.
Both routes require a clinical assessment to ensure the medication is safe for you. Use our free BMI calculator to understand your starting point, and our GLP-1 weight loss calculator to project potential outcomes alongside your prescriber's 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.
Can I get Mounjaro on the NHS for free?
Mounjaro is available on the NHS through specialist weight management services for eligible adults. However, access is limited and involves referral, assessment, and often significant waiting times. Your GP can refer you to your local tier 3 service if you meet criteria. Private prescription is faster but not covered by the NHS.
How much does a Mounjaro KwikPen cost in the UK?
Private costs range from approximately £150–£320 per month depending on dose. Each KwikPen contains four weekly injections. Starting doses are cheaper than maximum doses. Costs vary between providers, so it's worth comparing. Always check what's included in the quoted price.
Do I need a prescription to buy Mounjaro in the UK?
Yes. Mounjaro is prescription-only. You cannot buy it without a valid UK prescription from a licensed prescriber. Private prescriptions require an online clinical assessment. NHS prescriptions require GP referral and specialist assessment. Never purchase without a genuine UK prescription.
How long does it take to get Mounjaro privately in the UK?
Private access is typically faster than NHS. After completing an online consultation with a registered prescriber, if approved, you usually receive your prescription within 2–5 working days. Delivery to your home then takes 2–5 days. Total time from initial consultation to first injection: approximately 5–10 working days.
What's the difference between Mounjaro and Wegovy in terms of UK cost?
Both are prescription-only. Private costs are similar — roughly £150–£320 monthly. Mounjaro is a dual GIP/GLP-1 injection, while Wegovy is GLP-1-only. Maximum doses differ: Mounjaro goes to 15 mg weekly, Wegovy to 2.4 mg weekly. Your prescriber will advise which is appropriate for you based on your health profile.
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.