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 Syringe & KwikPen — How to Access in the UK
Mounjaro doesn't come in a traditional syringe — it's delivered as a pre-filled KwikPen injection device that you use once weekly. Understanding the device, how to access it, and what it costs in the UK can help you make an informed decision about this prescription weight management medication. This guide covers NHS and private routes, costs, and the practical steps to get started.
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Calculate Your BMI Instantly
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 Cost & Access Routes for Mounjaro
Mounjaro (tirzepatide) is available in the UK through two main routes: NHS specialist weight management services and private online prescribing. NHS access is through tier 3/4 specialist services following GP referral, though regional availability and waiting lists vary significantly — some areas have waits of many months. Private access is available through GPhC-registered online pharmacies following an online clinical assessment with a UK-licensed prescriber. Costs typically range from £129 to £320 per month depending on your dose. Each KwikPen contains four pre-filled pens (four weeks' supply), so monthly cost varies: a 5mg dose costs less than the maximum 15mg dose. Private prescribing avoids NHS waiting lists but requires payment upfront.
- NHS: Free at point of use but limited availability and longer waits
- Private: Faster access, requires upfront payment, costs vary by dose and provider
- Each KwikPen = 4 weekly injections
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 Access Mounjaro — NHS vs Private Route
NHS route: Ask your GP for a referral to your local tier 3 weight management service. You'll be assessed for eligibility (BMI 30+, or 27+ with weight-related health conditions). If approved, the service prescribes and monitors you, but you may wait months. Private route: Complete an online health questionnaire with a UK-licensed prescriber who assesses your suitability. If approved, your prescription is sent to a GPhC-registered pharmacy for dispensing. The whole process typically takes 3–7 days. Both routes require you to use the KwikPen exactly as instructed, starting at 2.5mg and increasing gradually over 16+ weeks to a maximum of 15mg. Use our GLP-1 weight loss calculator to explore projected outcomes at different doses alongside lifestyle changes.
- 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 exactly is the Mounjaro syringe?
Mounjaro doesn't use a traditional syringe — it's delivered as a pre-filled KwikPen auto-injection device. Each pen contains one 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg, or 15mg dose. You inject once weekly into your stomach, thigh, or upper arm. Each KwikPen is disposable after one use.
How much does Mounjaro cost in the UK privately?
Private costs range from approximately £129 to £320 per month depending on your dose. A 5mg dose costs less than higher doses. Each monthly prescription is a box of four pre-filled pens (four weeks' supply). Always check with individual providers for exact pricing.
How do I get Mounjaro on the NHS?
Ask your GP for a referral to your local NHS tier 3 specialist weight management service. You'll be assessed for eligibility (BMI 30+ or 27+ with health conditions). If approved, the service prescribes and monitors you free of charge, though waiting lists vary by region.
What's the difference between Mounjaro and Wegovy KwikPens?
Both are once-weekly pre-filled pens but contain different medications. Mounjaro contains tirzepatide (a dual GIP and GLP-1 agonist), while Wegovy contains semaglutide (a GLP-1 agonist only). They have different dose ranges and titration schedules. Mounjaro's KwikPen goes up to 15mg, Wegovy up to 2.4mg.
How long does an online assessment take before I can get Mounjaro?
An online consultation typically takes 10–15 minutes. The prescriber reviews your health questionnaire and medical history, then makes a decision. If approved, your prescription is sent to the pharmacy within 24 hours and usually arrives within 3–7 days. Faster than NHS routes in most areas.
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.