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 Dosage Levels in the UK: Complete Guide
Mounjaro (tirzepatide) is a once-weekly injection available through NHS specialist weight management services and private prescribing in the UK. Understanding the dosage levels is essential for anyone considering this prescription-only treatment. Mounjaro starts at a low dose and gradually increases every four weeks, with a maximum dose of 15mg per week. This guide explains how Mounjaro dosing works within the UK prescribing context, what to expect at each level, and how your GP or prescriber will assess your suitability for treatment. Individual results vary, and dosage is tailored to your personal health needs.
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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 Dosage Escalation Schedule and Titration
Mounjaro is prescribed as a step-wise dose escalation, with each injection delivered via a pre-filled KwikPen device. Starting at 2.5mg, the dose increases by 2.5mg every four weeks until reaching your optimal maintenance dose or the maximum of 15mg per week.
- Weeks 1–4: 2.5mg — starter dose to assess tolerance
- Weeks 5–8: 5mg — first escalation point
- Weeks 9–12: 7.5mg — further increase if tolerated
- Weeks 13–16: 10mg — mid-range maintenance option
- Weeks 17–20: 12.5mg — higher maintenance dose
- Week 21+: 15mg — maximum licensed dose
Prescribers do not automatically escalate every patient to 15mg. Your GP or specialist will assess tolerability, side effects, and effectiveness at each stage. Some patients achieve their weight loss goals at lower doses like 5mg or 10mg. A minimum of four weeks must pass between dose increases. Each KwikPen contains four weekly injections (one month's supply).
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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
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NHS Eligibility and Tier 3 Prescribing in the UK
In the UK, Mounjaro is available through NHS specialist tier 3 weight management services following NICE approval for specific eligibility criteria. You must have a BMI of 30kg/m² or above, or 27–29.9kg/m² with a weight-related health condition such as type 2 diabetes, high blood pressure, or sleep apnoea. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds may apply (from 27.5kg/m²). Access typically requires referral from your GP to a specialist weight management service. NHS availability varies significantly by region and ICB funding. Waiting times can be lengthy in many areas. Alternatively, private prescribing is available through UK-licensed online clinics following a clinical assessment. Calculate your personal BMI using our free BMI calculator to understand your starting point, and discuss NHS referral options with your GP.
- 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 starting dose of Mounjaro in the UK?
The starting dose is 2.5mg once weekly. This lower dose helps your body adjust and allows your prescriber to monitor tolerance before escalation. You remain on 2.5mg for four weeks, then typically move to 5mg if tolerated well.
Can I stay on a lower Mounjaro dose instead of going to 15mg?
Yes. Your prescriber will not force escalation to maximum dose. Many patients achieve effective weight loss at 5mg, 10mg, or 12.5mg. Escalation is individualised based on your results, side effects, and health goals.
How often do Mounjaro doses increase?
Doses increase every four weeks at minimum. Your prescriber may delay escalation if you experience side effects or prefer to stay on your current dose longer. There is no set timeline—escalation is tailored to you.
How is Mounjaro prescribed through the NHS in the UK?
Mounjaro is prescribed through specialist tier 3 weight management services following NICE approval. You typically need GP referral and meet specific BMI and health criteria. Availability varies by region and waiting lists can be months to years in some areas.
Is there a difference between NHS and private Mounjaro dosing?
No. The dosing schedule (2.5mg to 15mg, once weekly) is identical whether prescribed through NHS services or private clinics. Clinical assessment and monitoring remain important regardless of prescribing route.
Ready to take control of your weight loss journey?
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