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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2.5mg Mounjaro in ML — How Much Volume & UK Cost
The 2.5mg starting dose of Mounjaro (tirzepatide) contains 2.5mg of active ingredient in a fixed volume within the KwikPen pre-filled injector. Understanding the exact volume, cost, and how to access Mounjaro in the UK — whether through NHS specialist services or private prescription — helps you plan your weight management journey. This guide covers everything you need to know about accessing this prescription-only medication.
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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.
How to Access Mounjaro in the UK & What It Costs
Mounjaro is available in the UK through two main routes:
- NHS route: Tirzepatide (Mounjaro's active ingredient) is approved by NICE for NHS use in specialist weight management services. However, NHS access is limited to tier 3/4 specialist services — not standard GP prescribing. Waiting lists vary significantly by region, with some areas having waits of several months or longer. Your GP can refer you to your local specialist weight management service if you meet the BMI and health criteria.
- Private route: Mounjaro is available through GPhC-registered online prescribing services following an online clinical assessment. Private costs typically range from £150–£250+ per month depending on your dose (the 2.5mg starting dose is usually at the lower end of the price range). Once prescribed, the KwikPen is dispensed and delivered to your home. Results from the SURMOUNT clinical trials showed Mounjaro can help achieve weight loss when combined with diet and lifestyle changes, though individual results vary significantly.
Whichever route you choose, a prescriber will assess your eligibility based on your BMI, health conditions, and medical history before issuing a prescription.
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.
NHS vs Private Access — What to Expect
NHS access is free at point of use but involves referral to a specialist service, clinical assessment, and often substantial waiting lists. You'll receive ongoing support and monitoring through the NHS service. Private access is faster — typically days rather than months — but you pay privately for the prescription and medication. An online consultation with a UK-licensed prescriber takes 10–20 minutes and covers your medical history, current medications, weight, height, and health goals. If approved, your prescription is sent to a GPhC-registered pharmacy and your KwikPen arrives within 1–3 working days. Use our free GLP-1 weight loss calculator to estimate potential results at different doses, and track your progress with our progress tracker once you begin treatment. Either way, Mounjaro is prescribed as part of a comprehensive approach including reduced-calorie diet and increased physical activity.
- 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 volume is in a 2.5mg Mounjaro KwikPen?
Each 2.5mg dose of Mounjaro contains the active ingredient tirzepatide in a total volume of 0.5 mL within the pre-filled KwikPen. The exact formulation is proprietary to Eli Lilly, but the KwikPen is designed to deliver the precise dose in a single weekly injection. The pen itself holds enough for four weekly doses (4 weeks supply).
How much does 2.5mg Mounjaro cost privately in the UK?
Private Mounjaro costs in the UK typically range from £150–£220 per month at the 2.5mg starting dose, though prices vary between prescribing providers. This is the cost of the medication itself; online consultations are usually £40–£80 separately. Costs increase with higher doses (5mg, 10mg, 15mg). Some private providers offer package deals or subscription models. Always check the total cost with your chosen provider before committing.
Can I get Mounjaro on the NHS in the UK?
Yes — Mounjaro (tirzepatide) is approved by NICE for use within NHS specialist weight management services. However, it's not available through standard GP prescribing. You need a referral to a tier 3/4 specialist service, which means waiting lists in many areas. Eligibility requires a BMI of 30+ (or 27+ with weight-related health conditions). Access varies significantly by region and ICB funding.
What's the difference between NHS and private Mounjaro access?
NHS access is free but involves months of waiting and requires specialist referral. Private access is faster (days) and doesn't require NHS referral, but you pay privately (typically £150–£250/month). Both routes require clinical assessment and prescription from a UK-licensed prescriber. NHS provides ongoing support; private services vary in aftercare provided.
Do I need a prescription for Mounjaro in the UK?
Yes — Mounjaro is a prescription-only medicine in the UK. You cannot buy it over the counter. You must be assessed and prescribed by a UK-licensed prescriber (either NHS or private). A clinical assessment covers your weight, height, BMI, medical history, current medications, and weight-related health conditions to determine eligibility and suitability.
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.