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
Mounjaro 15mg — What You Need to Know About the Maximum Dose in the UK
Mounjaro 15mg is the highest licensed dose of tirzepatide available in the UK. This is the maximum dose reached after dose titration, typically from week 21 onwards if clinically appropriate. Understanding how the 15mg dose fits within the UK prescribing pathway, NHS NICE guidance, and your individual eligibility can help you work with your GP or prescriber to explore whether this treatment is suitable for you. This guide covers NHS access routes, eligibility criteria, and the clinical context around this maximum dose.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
NHS Access and NICE Guidance for Mounjaro in the UK
NICE approval: NICE has approved tirzepatide (Mounjaro) for use within NHS specialist weight management services for eligible adults. However, NHS access to Mounjaro remains limited and varies significantly by region—availability depends on your local Integrated Care Board (ICB) commissioning decisions and tier 3 weight management service capacity.
Eligibility for NHS consideration: You may be eligible if you have a BMI of 30 or above, or 27–29.9 with weight-related health conditions (type 2 diabetes, prediabetes, hypertension, dyslipidaemia, sleep apnoea, or cardiovascular disease history). Adults of South Asian, Chinese, Black African, or Black Caribbean heritage may be eligible at lower BMI thresholds (from 27.5).
The 15mg dose: This maximum dose is typically reached after at least 16–20 weeks of gradual dose increases, starting from 2.5mg. Reaching 15mg does not happen immediately—it requires clinical assessment and patience with the titration schedule.
Check our free GLP-1 weight loss calculator to explore potential outcomes at different doses, and use our BMI calculator to confirm your eligibility baseline.
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 Specialist Services vs Private Route — How to Access Mounjaro in the UK
NHS route: Access through tier 3 specialist weight management services requires a GP referral. Waiting lists can be lengthy (months to over a year in many areas), and regional availability is inconsistent. If approved, the NHS covers the full cost of the medication and monitoring.
Private route: Available through GPhC-registered online prescribing services following a clinical assessment. Private access is faster (often days to weeks) and does not require NHS referral, but you pay for the prescription and ongoing supply. The 15mg dose costs approximately £250–£320 per month depending on your provider.
Important: Whether NHS or private, reaching the 15mg dose requires sustained clinical follow-up and dose adherence. Your prescriber will only escalate you to 15mg if lower doses have been tolerated and previous weight management goals warrant further escalation.
Track your progress with our free progress tracker to monitor weight changes if you begin treatment.
- 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's the difference between Mounjaro 15mg and lower doses like 5mg or 10mg?
Each dose is a step in a titration schedule. You start at 2.5mg and increase every 4 weeks if tolerated. The 15mg dose is the maximum—clinical trials showed it produced average weight loss of around 21% of body weight, compared to roughly 15% at 5mg. Individual results vary, and not everyone needs to reach 15mg to achieve their goals.
Can I get Mounjaro 15mg on the NHS immediately?
No. NHS access varies by region and tier 3 service availability. You'd need a GP referral, clinical assessment, and would start at 2.5mg, titrating upward over months. Even then, NHS Mounjaro availability is limited in many areas—some regions have long waiting lists or restricted access.
How long does it take to reach the 15mg dose?
At least 20–24 weeks if you start at 2.5mg and escalate every 4 weeks without pauses. In practice, with real-world tolerability and clinical decisions, reaching 15mg often takes 5–6 months or longer. Your prescriber will only continue escalating if previous doses were well-tolerated.
Is the 15mg dose the only option, or can I stop at a lower dose?
You can stop at any dose. Many people achieve their weight loss goals at 5mg, 7.5mg, or 10mg. The 15mg dose is available for those who need additional benefit and tolerate the medication well. This is a decision made with your prescriber based on your individual response and health goals.
What's the cost difference between Mounjaro 15mg and lower doses privately?
Mounjaro costs are typically based on the pen dose, not the volume. A 15mg KwikPen usually costs around £250–£320 per month privately, while lower-dose pens (like 5mg) cost similarly. Always confirm pricing with your prescriber, as costs vary by provider and any promotional offers available.
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.