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 to Use Mounjaro in the UK: Access, Cost & Administration
Mounjaro (tirzepatide) is a once-weekly injectable prescription weight management medication available in the UK through NHS specialist services and private online prescribing routes. If you've been prescribed Mounjaro or are considering it, understanding how to use it properly—including storage, injection technique, and dose escalation—is essential for safe and effective treatment. This guide covers everything you need to know about accessing, using, and managing Mounjaro in the UK.
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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.
Accessing Mounjaro in the UK: NHS vs Private Routes
In the UK, you can access Mounjaro through two main routes: NHS specialist services or private prescription. The NHS route requires referral from your GP to a tier 3 or tier 4 specialist weight management service, though availability and waiting times vary significantly by region and integrated care board (ICB). NICE has approved tirzepatide for use within NHS specialist weight management services, but access remains inconsistent across the country—some regions have substantial waiting lists, whilst others may have limited availability.
The private route involves an online consultation with a UK-licensed prescriber following a health questionnaire assessment. If approved, a prescription is issued and dispensed by a GPhC-registered pharmacy. This route typically offers faster access without NHS waiting times but involves out-of-pocket costs. Private Mounjaro costs vary by dose and provider, generally ranging from £129 to £320+ per month depending on the dose strength and pharmacy.
- NHS access: free but may involve waiting lists
- Private access: faster, out-of-pocket costs
- Both routes require clinical assessment by a licensed prescriber
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.
How to Use Your Mounjaro KwikPen: Storage, Injection & Dose Escalation
Once prescribed, your Mounjaro KwikPen arrives as a pre-filled injection device containing a 4-week supply (four doses). Store unopened pens in the fridge at 2–8°C; do not freeze. After first use, you can keep the pen at room temperature below 30°C for up to 30 days. Inject once weekly on the same day, rotating between stomach, upper thigh, and upper arm sites. Follow your prescriber's dose schedule: starting at 2.5 mg with 4-week intervals between increases, escalating to 5 mg, 7.5 mg, 10 mg, 12.5 mg, and maximum 15 mg based on tolerability and response. Use our free weight loss calculator to track projected results as your dose increases. Nausea and stomach symptoms are common initially and often improve as your body adjusts; contact your prescriber if side effects persist or worsen.
- 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 costs typically range from £129 to £320+ per month depending on dose strength and pharmacy. Starting doses (2.5–5 mg) are usually cheaper than maximum doses (15 mg). Prices vary between providers, so comparing online prescribers can help you find the best cost. Always ensure you're using a GPhC-registered pharmacy.
Can I get Mounjaro free on the NHS?
Yes, Mounjaro is available free on the NHS through specialist tier 3 and tier 4 weight management services. However, you'll need a GP referral and may face waiting lists. Availability varies significantly by region and integrated care board. Contact your GP to ask about NHS specialist weight management services in your area.
What is the starting dose of Mounjaro, and how does it increase?
You start on 2.5 mg once weekly for 4 weeks. After that, doses typically increase every 4 weeks: 5 mg, 7.5 mg, 10 mg, 12.5 mg, and finally 15 mg (maximum). Your prescriber may adjust the pace based on how well you tolerate the medication and any side effects you experience.
How do I inject Mounjaro using the KwikPen?
Remove the KwikPen from the fridge 15 minutes before injection. Check the liquid is clear. Pinch skin on your stomach, thigh, or upper arm, insert the needle at a 90-degree angle, and press the injection button until you hear a click. Hold for 3 seconds, then remove. Rotate injection sites weekly to avoid irritation.
Can I use MyWeightCheck tools to track my Mounjaro progress?
Yes. Use our free BMI calculator to monitor your BMI as you progress through doses, and our GLP-1 weight loss calculator to see projected results at different dose levels. Our progress tracker also helps you log weekly weight changes and track your journey alongside Mounjaro treatment.
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.