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 Mounjaro 3.75mg?
The Mounjaro KwikPen doesn't work with "clicks"—each pre-filled pen delivers a fixed dose as a single weekly injection. A 3.75mg dose isn't a standard NHS or UK-licensed tier for Mounjaro; the approved doses in the UK are 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg, and 15mg. If you're prescribed tirzepatide through the NHS or a private UK prescriber, you'll receive the exact dose your GP or specialist determines is right for you during dose titration. This guide explains how Mounjaro dosing works in the UK and what to expect from your treatment.
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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.
Mounjaro KwikPen Dosing—How It Works in the UK
Each Mounjaro KwikPen is a pre-filled auto-injection device that delivers one complete weekly dose in a single injection. There are no clicks or dial adjustments—you simply remove the pen from the fridge, wait 15 minutes for it to reach room temperature, select an injection site (stomach, thigh, or upper arm), and inject. Every pen comes pre-loaded with a single, fixed dose.
The standard UK-licensed Mounjaro doses are: 2.5mg (starting dose), 5mg, 7.5mg, 10mg, 12.5mg, and 15mg (maximum). A dose of 3.75mg is not an approved tier—it falls between the 2.5mg starting dose and the 5mg escalation dose. If your NHS specialist or private prescriber wants you on an intermediate dose, they would typically ask you to remain on 2.5mg for longer or move directly to 5mg based on your response.
- Each KwikPen contains exactly 4 weekly doses (one month's supply)
- Minimum 4 weeks on each dose before increasing
- Dose adjustments happen at 4-week intervals as part of titration
- Your prescriber reviews your progress and adjusts at each step
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.
NHS Mounjaro Dosing and Escalation Timeline
If you're prescribed Mounjaro through an NHS specialist weight management service, your dose will follow a structured escalation plan starting at 2.5mg and increasing every 4 weeks if tolerated. Your GP or tier 3 specialist will assess your weight loss progress, side effects, and health markers before moving to the next approved dose level.
For those accessing Mounjaro privately through a UK-licensed prescriber, the same dose structure applies—you'll be prescribed the exact dose your prescriber recommends based on your individual assessment. Use our free GLP-1 weight loss calculator to estimate potential outcomes at different approved doses, and track your progress with our weight tracker as you move through dose escalation. Always contact your prescriber before adjusting doses or if you experience significant side effects.
- 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.
Can I adjust the dose dial on a Mounjaro KwikPen myself?
No. The KwikPen is pre-filled with a fixed dose—there is no dose dial or click adjustment. Each pen delivers one complete weekly injection. Dose changes are made by your prescriber, who supplies you with a new KwikPen at the next dose tier after assessing your progress.
Is 3.75mg an available Mounjaro dose in the UK?
No. Approved UK doses are 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg, and 15mg. If your prescriber wants a dose between tiers, they typically extend your time on 2.5mg or advance directly to 5mg based on your individual response and tolerance.
How does Mounjaro dose titration work on the NHS?
You start at 2.5mg for 4 weeks. If tolerated well, your specialist increases you to 5mg at week 5, then 7.5mg at week 9, and so on—escalating every 4 weeks up to the maximum effective dose. Your GP monitors side effects and weight loss at each step.
What happens if I can't tolerate a dose increase?
Your prescriber may keep you on your current dose longer, reduce back to the previous dose, or pause escalation. Some people reach their target weight loss on lower doses. Always discuss side effects with your GP—they can adjust your plan based on your individual experience.
Where can I get Mounjaro prescribed in the UK?
Through NHS specialist tier 3 weight management services (via GP referral) or privately through a GPhC-registered online prescriber following a clinical assessment. NHS availability and waiting times vary significantly by region and local ICB funding.
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.