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's the Highest Dosage of Mounjaro in the UK?
The highest dosage of Mounjaro available in the UK is 15 mg once weekly. This is the maximum maintenance dose reached after a gradual dose escalation process over several months. Not everyone requires or reaches the 15mg dose — many people achieve effective weight loss at lower doses. Your prescriber will assess what dose is appropriate for you based on your individual response and health needs. Both NHS specialist services and private prescribers follow the same evidence-based dose titration schedule.
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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.
Understanding Mounjaro Dose Titration and Maximum Dosing
Mounjaro (tirzepatide) is titrated gradually over approximately 20 weeks to reach the 15mg maximum dose. Starting at 2.5 mg, the dose increases every 4 weeks: 2.5 mg → 5 mg → 7.5 mg → 10 mg → 12.5 mg → 15 mg. Each dose is administered once weekly as a KwikPen injection. You do not automatically progress to 15 mg — your prescriber will assess your response, side effects, and weight loss at each stage. Many people experience significant weight loss at 5 mg, 10 mg, or 12.5 mg and may choose to remain at these maintenance doses. Clinical trial data (SURMOUNT-1) showed that the average weight loss reached approximately 20.9% of body weight at the 15 mg dose over 72 weeks, but individual results vary considerably. Some people achieve their weight loss goals at lower doses and do not progress further.
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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.
Accessing the Highest Mounjaro Dose: NHS vs Private Routes in the UK
NHS route: Access to Mounjaro on the NHS is through specialist tier 3 weight management services. Your GP can refer you, but availability is limited and regional variation is significant. Waiting lists can be several months to years depending on your area. Once accessed, the dose is managed by the specialist team according to NHS guidelines.
Private route: Private prescribers can initiate Mounjaro following an online consultation. No referral is needed, and you can start treatment much faster — typically within days to weeks. A GPhC-registered pharmacy will dispense your prescription. Costs vary by dose: lower doses (2.5–7.5 mg) typically cost £129–£180 per month, whilst higher doses (10–15 mg) range from £200–£320 per month depending on your provider. Try our GLP-1 weight loss calculator to understand how different doses may support your weight loss goals.
- 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.
Can I skip straight to the 15mg Mounjaro dose?
No. UK prescribers follow a mandatory 4-week titration schedule for safety and tolerability. You must start at 2.5 mg and progress gradually. This allows your body to adjust and helps your prescriber identify the effective dose for you. Skipping doses or rapid escalation increases the risk of significant side effects like severe nausea or vomiting.
What if I can't tolerate higher Mounjaro doses?
If you experience intolerable side effects at a particular dose, your prescriber may recommend remaining at your current dose or reducing it. There's no requirement to reach 15 mg. Many people achieve good weight loss outcomes at 5 mg, 10 mg, or 12.5 mg. Discuss your experience with your prescriber — they can advise whether to pause escalation or adjust.
Is 15mg Mounjaro more expensive than lower doses?
Yes, generally. Private costs increase with dose: 15 mg typically costs £250–£320 per month, whilst 5 mg costs around £129–£150 per month. If you access Mounjaro via the NHS, you do not pay per dose once approved. Check with your provider for their specific pricing at different dose strengths.
How long does it take to reach 15mg Mounjaro?
Approximately 20 weeks (5 months) if you escalate every 4 weeks without pause. In reality, many people take longer due to side effects, scheduling, or reaching their weight loss goal at a lower dose. Your prescriber will determine your individual escalation timeline based on your tolerance and response.
Does Mounjaro work better at 15mg than at lower doses?
Clinical data shows slightly greater average weight loss at 15 mg compared to lower doses, but the difference between individuals is significant. Some people achieve their personal weight loss goals at 5 mg or 10 mg. Your prescriber will help identify the dose that balances effectiveness and tolerability for your specific situation.
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.