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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What Is the Maximum Mounjaro Dose in the UK?
The maximum Mounjaro dose is 15 mg once weekly, reached after a gradual 20-week dose escalation starting from 2.5 mg. Not all patients need the highest dose — your prescriber will determine the right dose for your individual health needs. This guide covers UK dosing, how to access Mounjaro through NHS or private prescription, what it costs, and the dose titration schedule you'll follow. Our GLP-1 weight loss calculator can help you understand projected outcomes at different doses based on clinical trial data.
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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 Dosing Schedule and Maximum Dose in the UK
Mounjaro (tirzepatide) is available as pre-filled KwikPen injections, taken once weekly. The standard dose escalation schedule takes approximately 20 weeks to reach the maximum 15 mg dose:
- Weeks 1–4: 2.5 mg (starting/adjustment dose)
- Weeks 5–8: 5 mg (first maintenance dose)
- Weeks 9–12: 7.5 mg (escalation)
- Weeks 13–16: 10 mg (further escalation)
- Weeks 17–20: 12.5 mg (escalation)
- Week 21+: 15 mg (maximum maintenance dose)
Each KwikPen contains 4 weeks' worth of injections (4 × the dose shown on the pen). Your prescriber will assess whether you need to escalate beyond 5 mg, or whether a lower maintenance dose is appropriate for you. Not everyone requires the maximum 15 mg dose — clinical response and tolerability vary between individuals. NICE guidance and the NHS support tirzepatide for eligible adults, though availability through NHS specialist weight management services varies significantly by region.
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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.
Mounjaro Cost and How to Access It in the UK
NHS access: Mounjaro is available through NHS specialist tier 3/4 weight management services following referral from your GP. Availability and waiting times vary significantly by region. Some ICBs (Integrated Care Boards) have long waiting lists; others have more immediate access. There is no direct cost to you via the NHS if prescribed through specialist services.
Private access: Mounjaro is available through GPhC-registered online pharmacies following an online clinical assessment with a UK-licensed prescriber. Private costs typically range from £129–£320 per month depending on the dose — lower doses (2.5–5 mg) cost less, whilst higher doses (10–15 mg) cost more. Each KwikPen (4-week supply) is dispensed following prescription. You can use our BMI calculator to confirm your eligibility before seeking a private prescription.
- 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 is the maximum Mounjaro dose?
The maximum Mounjaro dose is 15 mg once weekly. Most patients escalate gradually from 2.5 mg over 20 weeks. Some patients reach full dose in 8 weeks; others stay on lower maintenance doses of 5–10 mg if that's sufficient for their weight management needs.
How much does Mounjaro cost on the NHS in the UK?
Mounjaro is free if prescribed through NHS specialist weight management services. However, NHS access requires referral from your GP and availability varies by region — waiting lists can be several months to over a year in some areas.
How much does private Mounjaro cost per month?
Private Mounjaro costs typically range from £129–£320 per month depending on dose. Lower doses (2.5–5 mg) are cheaper; higher doses (10–15 mg) cost more. Each KwikPen contains 4 weeks of injections. Prices may vary slightly between different UK online prescribing services.
Can I switch from a lower Mounjaro dose to the maximum dose?
Yes, your prescriber will gradually increase your dose every 4 weeks as tolerated. However, not everyone needs to reach 15 mg — many people achieve good weight management results on 5–10 mg. Your prescriber will recommend the dose that works best for your response and side effects.
Is Mounjaro dose the same as Wegovy dose?
No. Mounjaro and Wegovy are different medications with different dosing schedules. Mounjaro is a dual GIP+GLP-1 agonist with a maximum of 15 mg weekly; Wegovy is a GLP-1 agonist only with a maximum of 2.4 mg weekly. Approximate equivalence exists (Mounjaro 10 mg ≈ Wegovy 1.7 mg) but any medication switch must be managed by your prescriber.
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.