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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Understanding Mounjaro KwikPen Clicks and Doses
The Mounjaro KwikPen uses a dial-and-click mechanism to deliver each dose of tirzepatide. Each pen contains four doses across a four-week period, and the number of clicks required varies by dose strength. This guide explains how the pen works, how many clicks correspond to each dose, and what you need to know about using your Mounjaro prescription correctly in the UK.
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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 the Mounjaro KwikPen Dosing Mechanism Works
The Mounjaro KwikPen is a pre-filled, colour-coded injection device that delivers tirzepatide once weekly. Each KwikPen contains four prefilled doses, giving you a four-week supply. The pen uses a rotary dial mechanism: you select your prescribed dose using the coloured dial, and the pen automatically displays how many clicks are needed to deliver that dose correctly.
- Colour coding: Each dose strength has a specific colour (2.5mg = yellow, 5mg = purple, 7.5mg = grey, 10mg = blue, 12.5mg = red, 15mg = teal)
- Click mechanism: Once you rotate the dial to your dose, the pen shows the number of clicks required — this ensures accurate delivery every time
- Safety feature: The click system prevents under- or over-dosing
Always follow your prescriber's instructions for your specific dose. Your GP or the prescriber who assessed you will confirm which dose you should use.
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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.
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Mounjaro Dose Titration Schedule and When Doses Change
Mounjaro dosing follows a step-wise increase over several weeks. You start at 2.5mg and increase gradually — staying on each dose for at least four weeks before increasing. The full progression is: 2.5mg (weeks 1–4), 5mg (weeks 5–8), 7.5mg (weeks 9–12), 10mg (weeks 13–16), 12.5mg (weeks 17–20), and 15mg (week 21 onwards). The maximum dose is 15mg once weekly. Your prescriber will monitor your progress and may adjust your dose based on your response and any side effects. Always check your prescription paperwork to confirm which dose you are currently on.
- 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 many clicks does a Mounjaro 2.5mg dose require?
The 2.5mg dose is the yellow KwikPen and typically requires a specific number of clicks set on the dial. Your individual pen will display the exact number on the dial once selected. The prescription paperwork will also confirm this. Always follow the instructions that come with your pen.
What if I'm not sure which dose I'm supposed to be on?
Check your prescription paperwork or the label on your KwikPen — it will clearly state your prescribed dose. If you're unsure, contact the prescriber who issued your prescription (your GP or specialist service) before injecting. Never guess at your dose.
Can I use a Mounjaro pen from an old prescription at a different dose?
No — only use the pen and dose that matches your current prescription. If your dose has increased, you need a new prescription for the higher-dose pen. Using the wrong dose could be unsafe. Your prescriber will issue new pens as your dose increases.
Does every Mounjaro dose have a different number of clicks?
Yes — each dose strength has its own colour and click requirement. The KwikPen dial will display the correct number of clicks for your selected dose. This is a safety feature to ensure you always get the right amount of medication.
What if my pen doesn't click the right number of times?
If your pen malfunctions or doesn't deliver the expected clicks, stop using it and contact your prescriber or pharmacy immediately. Do not attempt to use a damaged pen. They will provide a replacement pen to ensure you don't miss a dose.
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.