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
Free tracker included with every download this week
How Many Clicks For 2.5 Mg Mounjaro?
The 2.5 mg starting dose of Mounjaro uses a specific number of clicks on the KwikPen device to deliver the correct amount. Each Mounjaro KwikPen is pre-filled and colour-coded by dose, making it straightforward to identify and administer your prescription. Understanding how to use your Mounjaro KwikPen correctly is essential for safe and effective treatment. This guide explains the mechanics of the pen and how dosing works 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.
Understanding Mounjaro KwikPen Dosing
Mounjaro (tirzepatide) is dispensed in a pre-filled KwikPen auto-injection device. The 2.5 mg starter dose is delivered via a single click mechanism — you simply dial the dose number and click once to inject. The KwikPen automatically measures the correct amount of medication, so you don't need to count multiple clicks for a 2.5 mg dose.
- 2.5 mg dose: One click delivers the full 2.5 mg injection
- Colour-coded: The 2.5 mg pen has a specific colour band for easy identification
- Auto-injector: Once you set the dose dial, pressing the button triggers the injection automatically
- Needle length: The needle is very short (5 mm) — minimising discomfort
Each KwikPen contains four weekly doses, lasting one month. After your first injection, you'll continue once-weekly on your scheduled day, increasing to higher doses (5 mg, 7.5 mg, etc.) only after your prescriber advises, usually with at least 4 weeks between each dose escalation.
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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.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
How to Inject Mounjaro Safely
Before injecting, remove your KwikPen from the refrigerator and let it reach room temperature for 15–30 minutes. Choose your injection site — stomach (abdomen), upper thigh, or upper arm — and rotate sites weekly. Pinch the skin gently, push the pen firmly against your skin at a 90-degree angle, and press the button until you hear a click. Hold in place for 3 seconds to ensure the full dose is delivered. If you have questions about injection technique, your prescriber or pharmacist will demonstrate during your first appointment. Using our GLP-1 weight loss calculator can help you understand expected results alongside your dose progression.
- 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.
Does Mounjaro really use just one click for 2.5 mg?
Yes, the 2.5 mg Mounjaro KwikPen delivers the full dose with a single button press. The pen is pre-filled and auto-calibrated — you simply dial the dose number and click once. This design makes it straightforward and reduces injection errors.
What's the difference between Mounjaro and Wegovy injections?
Both are prescription-only weight management injections used once weekly, but Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. Mounjaro starts at 2.5 mg; Wegovy starts at 0.25 mg. Both require a clinical assessment before prescription.
Can I get Mounjaro on the NHS in the UK?
Mounjaro is available through the NHS, but access is through specialist tier 3 weight management services via referral from your GP. NICE has approved tirzepatide for use within NHS services, though availability and waiting times vary significantly by region.
What if I miss a Mounjaro injection?
If you miss your weekly injection, you can inject within 4 days of the missed date and continue your normal schedule. If more than 4 days have passed, skip that dose and take your next injection on the normal scheduled day.
Are there side effects when starting Mounjaro 2.5 mg?
The most common side effects in clinical trials include nausea, diarrhoea, vomiting, and constipation. These often reduce over time as your body adjusts. Starting at the lower 2.5 mg dose helps minimise side effects during the initial weeks. Always report persistent symptoms to your prescriber.
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.