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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Mounjaro 3.75mg: How Many Clicks and How It Compares to Wegovy
Mounjaro 3.75mg doesn't exist as a standard dose — the KwikPen delivery system uses colour-coded pen designs with pre-filled doses (2.5mg, 5mg, 7.5mg, 10mg, 12.5mg, and 15mg) rather than adjustable clicks. This guide explains how Mounjaro dosing actually works on the KwikPen, how it compares to Wegovy's dose progression, and the key differences between these two prescription weight loss injections available in the UK. Both require clinical assessment and are prescription-only medicines. Understanding the actual delivery mechanism helps clarify how these medications work and what to expect when prescribed.
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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 Dosing vs Wegovy Injection System
Mounjaro (tirzepatide) uses pre-filled KwikPen devices — each pen contains a single, fixed dose rather than adjustable clicks. The dose progression is: 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg, and 15mg. Each pen delivers four weekly injections (one month's supply), meaning you receive a new pen every month as your dose increases during titration.
Wegovy (semaglutide) uses a different delivery system — pre-filled auto-injection pens with doses of 0.25mg, 0.5mg, 1mg, 1.7mg, and 2.4mg. Like Mounjaro, each Wegovy pen also contains four weekly doses. Both medications are once-weekly injections, but Mounjaro's dual GIP and GLP-1 mechanism differs from Wegovy's single GLP-1 action.
In clinical trials (SURMOUNT-1 for Mounjaro, STEP-1 for Wegovy), participants lost approximately 15–21% and 15% body weight respectively, though individual results vary significantly. Both require reduced-calorie diet and increased physical activity alongside the medication.
Clinically BackedWeight Loss
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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.
Clinical Evidence and Individual Suitability
Neither Mounjaro nor Wegovy assures specific weight loss outcomes — eligibility and suitability depend on individual health factors assessed by your prescriber. Adults with a BMI of 30 or above, or 27+ with weight-related health conditions, may qualify for either medication in the UK. Use our free GLP-1 weight loss calculator to estimate potential outcomes at different doses, and check your BMI with our free BMI calculator to understand your starting point.
Your GP or licensed prescriber will assess which medication is appropriate based on your medical history, current medications, and health conditions. Both are prescription-only and available through NHS specialist weight management services or private online prescribing. Access, cost, and availability vary by region and service type.
- 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 3.75mg exist?
No. Mounjaro doesn't have a 3.75mg dose. The standard UK doses are 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg, and 15mg. You may be thinking of the 7.5mg dose, which is typically the third or fourth dose during the titration schedule. Each KwikPen is colour-coded and contains a pre-filled dose — not adjustable clicks.
How many clicks on a Mounjaro KwikPen?
Mounjaro KwikPens don't use clicks — they use colour-coded pre-filled doses. You simply inject the entire pen contents once weekly. Each pen automatically delivers the full dose of that strength. If you need help with injection technique, your pharmacist or healthcare team can demonstrate the correct method.
How does Mounjaro dosing compare to Wegovy?
Mounjaro starts at 2.5mg and increases weekly up to 15mg maximum. Wegovy starts at 0.25mg and increases to 2.4mg maximum. Mounjaro's dual GIP+GLP-1 mechanism differs from Wegovy's GLP-1-only action. Both are once-weekly injections with four doses per pen, but dosing schedules and mechanisms are different.
Can I choose my Mounjaro dose?
No. A prescriber determines your starting dose and escalation schedule based on your health, response, and tolerance. The standard schedule increases every 4 weeks unless side effects require a longer adjustment period. Your prescriber monitors your progress and adjusts timing as needed.
Which is better — Mounjaro or Wegovy?
Neither is universally "better" — suitability depends on individual health factors. Clinical trials show similar weight loss outcomes on average (15–21% vs 15% body weight), but individual results vary. Your prescriber will assess which is appropriate for you based on your medical history, eligibility criteria, and health conditions.
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.