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 in a Mounjaro 5mg Pen?
Each Mounjaro KwikPen is pre-filled with a specific dose and uses a click mechanism to deliver the full injection — there is no dose adjustment dial on the pen itself. A 5mg Mounjaro pen delivers the complete 5mg dose in a single injection, not through multiple clicks. Understanding how your Mounjaro KwikPen works is essential for safe use in the UK, whether you're receiving it through NHS specialist services or private prescription. This guide explains the pen mechanics, what to expect, and how tirzepatide dosing works in UK prescribing.
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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 the Mounjaro KwikPen Works
The Mounjaro KwikPen is a pre-filled, single-use injection device that delivers the entire prescribed dose in one injection. Unlike some older insulin pens with dial-up doses, the Mounjaro KwikPen does not require you to "click" to adjust the dose — the dose is already set by the manufacturer. When you inject, the pen delivers the full amount of tirzepatide (whether 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg, or 15mg) in approximately 5–6 seconds. You will hear and feel a click when the injection is complete, signalling that the dose has been delivered.
- One click per week: You inject once weekly on the same day each week
- Each pen contains 4 doses: One KwikPen supplies 4 weeks of treatment (4 injections)
- Injection sites: Stomach, upper thigh, or upper arm (rotate each week)
- No dose dial: The dose is fixed — your prescriber changes your dose by issuing a new pen strength
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.
Mounjaro Dose Escalation and NHS Eligibility
In the UK, Mounjaro dosing follows a structured dose titration schedule where your prescriber increases your dose every 4 weeks if needed. You start at 2.5mg for weeks 1–4, then move to 5mg for weeks 5–8, and continue escalating through 7.5mg, 10mg, 12.5mg, and up to the maximum 15mg dose. Each dose change requires a new prescription and new pen. NHS access is typically through tier 3 specialist weight management services following referral from your GP. Private prescription routes via UK-licensed online prescribers offer faster access without NHS referral. Your prescriber will assess your eligibility based on BMI and weight-related health conditions, and monitor your progress at each dose level before escalating.
- 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 the Mounjaro 5mg pen have a dose adjustment dial?
No. The Mounjaro KwikPen is pre-filled with a fixed dose set by the manufacturer. There is no dial to adjust the amount. The pen delivers the complete 5mg dose in one injection. Dose changes require a new prescription with a different pen strength.
How do I know when the full 5mg dose has been injected?
You will hear and feel a distinct click when the injection is complete, usually after 5–6 seconds. This click signals that the full dose has been delivered. Keep the needle in the skin for a few seconds after the click to ensure complete delivery.
How many injections come in one Mounjaro 5mg pen box?
Each Mounjaro KwikPen is pre-filled with one dose. A standard prescription typically includes 4 pens (one per week for 4 weeks). You receive the pens as a monthly supply, not individual pens for each injection.
What should I do if I don't hear or feel a click during injection?
Contact your prescriber or pharmacist immediately. A missing click may indicate the injection was not completed properly. Do not assume the dose was given. Seek urgent advice before your next scheduled injection.
Does the 5mg pen cost more than lower doses on NHS or private prescription?
NHS costs vary by region and are managed through your specialist service. Private costs typically increase with dose strength, but prices vary by online prescriber. Ask your prescriber about costs at each dose level before starting treatment.
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.