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 Many Clicks For 2.5 mg Mounjaro?
The 2.5 mg starting dose of Mounjaro (tirzepatide) requires 2 clicks on the KwikPen auto-injector device. This is the standard initial dose prescribed in the UK for adults beginning Mounjaro treatment. Each click on the pen advances the dose dial by 1.25 mg, so two clicks deliver the full 2.5 mg starting injection. Understanding the correct click count is essential for accurate dosing, and your prescriber or pharmacist will always confirm the exact number during your first dose.
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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.
Mounjaro KwikPen Dose Clicks — UK Prescribing Guide
The Mounjaro KwikPen is a pre-filled auto-injection device supplied by Eli Lilly. Each pen contains 4 pre-filled doses across 4 weeks. The dose dial on the pen clearly shows the number of clicks needed for each strength:
- 2.5 mg = 2 clicks
- 5 mg = 4 clicks
- 7.5 mg = 6 clicks
- 10 mg = 8 clicks
- 12.5 mg = 10 clicks
- 15 mg = 12 clicks
The 2.5 mg dose is the standard starting dose used in NHS and private prescribing in the UK. Following your first injection at 2.5 mg, your prescriber will typically increase the dose by 2.5 mg increments each week (or every 4 weeks depending on individual response and tolerability). The KwikPen's click mechanism is designed to be simple and accurate—the pen will not inject until you reach the selected dose, and it will automatically lock after injection. Always double-check the dose dial before injecting.
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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.
NHS Mounjaro Eligibility and Dose Titration Protocol
In the UK, Mounjaro is prescribed through NHS specialist weight management services (tier 3/4) and private online prescribing following clinical assessment. NICE guidance supports tirzepatide for weight management in adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions. Dose titration is gradual: you remain on 2.5 mg for the first 4 weeks, then progress to 5 mg for weeks 5–8, and so on, until reaching an effective maintenance dose (typically 10–15 mg). This slower approach compared to Wegovy allows your body to adjust and helps minimise side effects. Your GP or private prescriber will monitor your response and adjust timing based on tolerability and weight loss progress.
- 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.
Is 2.5 mg Mounjaro the same as the starting dose of Wegovy?
No. Mounjaro 2.5 mg is the standard starting dose for tirzepatide, while Wegovy (semaglutide) starts at 0.25 mg. These are different medications with different mechanisms. Mounjaro is a dual GIP and GLP-1 receptor agonist, whereas Wegovy is a GLP-1 only agonist. Use our GLP-1 weight loss calculator to compare projected outcomes between the two medications.
Can I stay on 2.5 mg Mounjaro long-term?
The 2.5 mg dose is intended as a starting dose only, typically used for the first 4 weeks. Your prescriber will increase it by 2.5 mg each week (or slower if needed for side effects) until you reach an effective maintenance dose, usually between 10–15 mg. Staying on 2.5 mg long-term is not standard practice and would be discussed with your prescriber.
What happens if I click the wrong number on my Mounjaro pen?
The KwikPen has built-in safety features—it won't inject until you've selected the correct dose. If you accidentally select the wrong number of clicks, simply turn the dose dial back to the correct number before injecting. If you've already injected the wrong dose, contact your prescriber or pharmacist immediately for guidance.
Does the NHS provide Mounjaro at 2.5 mg cost-free?
Mounjaro is available through NHS specialist weight management services, though regional availability varies significantly. Access is typically through tier 3 services following referral from your GP. Waiting lists can be lengthy in many areas. Alternatively, it's available privately through GPhC-registered online prescribers with UK-licensed prescribers conducting clinical assessments.
How long should I use 2.5 mg Mounjaro before increasing?
Standard UK prescribing guidance recommends staying on 2.5 mg for 4 weeks before titrating to 5 mg. However, your individual prescriber may adjust this timeline based on your side effects, tolerability, and response. Some people need longer adjustment periods. Always follow your prescriber's specific instructions and use our progress tracker to log your weight and any side effects during this initial phase.
Ready to take control of your weight loss journey?
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