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
Understanding Mounjaro Clicks and Doses in the UK
Mounjaro comes as a pre-filled KwikPen device, and each "click" on the pen delivers a precise dose of tirzepatide. The medication is available in six different doses ranging from 2.5 mg to 15 mg, dispensed once weekly. In the UK, you can access Mounjaro through NHS specialist weight management services or via private prescription following an online clinical assessment. Understanding how the pen works, what each dose delivers, and the associated costs will help you make an informed decision about this prescription weight loss medication. Use our free GLP-1 weight loss calculator to see how Mounjaro might fit into your weight management journey.
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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.
How Mounjaro Clicks and Doses Work
Mounjaro is administered using a KwikPen — a pre-filled, single-dose auto-injection device that delivers tirzepatide once per week. Each pen contains four weeks' worth of doses. The medication is available in six strengths: 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, and 15 mg. Your prescriber will start you on the lowest dose (2.5 mg) and increase it gradually every four weeks, provided you tolerate the previous dose well.
Unlike some injections that require a UK pharmacy adjustment, the KwikPen is a fixed-dose device — each click releases the exact dose needed for that week. You do not adjust the pen yourself; instead, your prescriber determines which strength you receive based on your individual response and any side effects you experience.
- Starting dose: 2.5 mg for weeks 1–4
- Standard maintenance: 5 mg (weeks 5–8), escalating as tolerated
- Maximum dose: 15 mg once weekly
The gradual dose increase approach (called dose titration) helps your body adjust to the medication and minimises nausea and gastrointestinal side effects.
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 Cost and Access Routes in the UK
NHS access: Mounjaro is available through NHS tier 3 specialist weight management services, though availability varies significantly by region and waiting lists can be lengthy. You will need a GP referral and must meet NICE eligibility criteria (BMI ≥30, or ≥27 with weight-related health conditions). Lower thresholds apply for South Asian, Chinese, Black African, and Black Caribbean adults.
Private prescription: Mounjaro is available through private online prescribing services following a clinical assessment with a UK-licensed prescriber. Monthly costs typically range from £129 to £320+ depending on your dose and provider, though prices vary. Each four-week supply costs differ based on whether you're on the starting dose (2.5 mg) or a higher maintenance dose. Private access offers faster availability without NHS waiting lists, but treatment costs are met by the patient.
Try our BMI calculator to check your starting point and understand your eligibility for weight loss treatment options.
- 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.
What exactly is a "click" on a Mounjaro pen?
A "click" is not a unit of measurement you control — it refers to the mechanical action of the pre-filled KwikPen injector. Each pen delivers a fixed dose set by your prescriber. You inject once weekly and cannot adjust the dose yourself. The pen is designed to be user-friendly for people managing their own injections at home.
How much does Mounjaro cost in the UK on the NHS?
Mounjaro is free on the NHS if prescribed through a specialist weight management service, but availability is limited and regional. NHS access requires a GP referral and assessment. Many areas have waiting lists of several months or longer. Private prescriptions typically cost £129–£320+ per month depending on your dose.
What's the difference between Mounjaro and Wegovy for UK users?
Both are prescription-only weight loss injections available in the UK. Mounjaro (tirzepatide) is a dual GIP/GLP-1 agonist with a starting dose of 2.5 mg. Wegovy (semaglutide) is a GLP-1 agonist with a starting dose of 0.25 mg. Mounjaro typically shows slightly higher average weight loss in clinical trials, but individual results vary. Both require clinical assessment.
How long before I see results with Mounjaro?
Most people notice reduced appetite or changes in food preferences within the first few weeks. Measurable weight loss typically becomes apparent after 4–8 weeks of consistent use. Clinical trials showed significant weight loss (15–21% average) over 72 weeks alongside a reduced-calorie diet and increased activity. Results vary between individuals.
Can I get Mounjaro privately without waiting for the NHS?
Yes. UK-licensed prescribers offer online consultations for private Mounjaro prescriptions. Following assessment, you can receive a prescription from a GPhC-registered pharmacy. This route bypasses NHS waiting lists but costs are paid privately. Prescribers assess your suitability based on your BMI, health history, and any weight-related 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.