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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How Much Does Mounjaro Dose Go Up To in the UK?
Mounjaro (tirzepatide) starts at 2.5 mg and increases gradually over several months, with a maximum dose of 15 mg once weekly in the UK. Your prescriber will adjust your dose based on your individual response and tolerance, typically increasing every 4 weeks if needed. Understanding the full dosing schedule helps you know what to expect during your weight management journey. Our GLP-1 weight loss calculator can help you explore potential outcomes at different tirzepatide doses.
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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 UK Dosing Schedule: Start to Maximum Dose
Mounjaro begins at a 2.5 mg starting dose for the first 4 weeks, allowing your body to adjust. Your prescriber then increases the dose every 4 weeks if tolerated:
- Weeks 1–4: 2.5 mg
- Weeks 5–8: 5 mg
- Weeks 9–12: 7.5 mg
- Weeks 13–16: 10 mg
- Weeks 17–20: 12.5 mg
- Week 21 onwards: 15 mg (maximum dose)
Each dose is delivered as a once-weekly injection using a pre-filled KwikPen device. You do not need to reach 15 mg — many people achieve good results at lower maintenance doses like 5 mg or 10 mg. Your GP or prescriber will assess your individual response and may pause escalation if you experience side effects or reach your target weight. The dose titration approach minimises nausea and other gastrointestinal side effects by allowing gradual adjustment.
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 vs Wegovy: Dose Comparison and NHS Access
Mounjaro and Wegovy follow different dosing schedules because they are different medications. Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist with a maximum of 15 mg weekly, whilst Wegovy (semaglutide) is a single GLP-1 agonist with a maximum of 2.4 mg weekly. In clinical trials, Mounjaro showed average weight loss of 15–21% of body weight, though individual results vary significantly. Both medications are prescription-only in the UK and require a clinical assessment before prescribing. Access is available through NHS specialist tier 3 weight management services (with potential waiting lists) or privately through GPhC-registered online prescribers following an online assessment.
- 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 stop Mounjaro dose increases before reaching 15 mg?
Yes. Your prescriber may pause escalation if you achieve good weight loss results, experience side effects, or reach your target weight at a lower dose. Many people stabilise at 5 mg, 10 mg, or 12.5 mg. Dose adjustments are based on your individual response and health, not a requirement to reach maximum.
What if I experience side effects during Mounjaro dose titration?
Inform your prescriber immediately. Common side effects (nausea, diarrhoea, vomiting) often improve as your body adjusts. Your prescriber may pause dose increases, reduce your dose, or provide additional guidance. Never stop Mounjaro suddenly without medical advice.
How long does it take to reach maximum Mounjaro dose?
Reaching the full 15 mg dose takes approximately 20–24 weeks (5–6 months) if doses increase as planned every 4 weeks without pausing. However, your actual timeline depends on your individual tolerance and prescriber's recommendations.
Is 15 mg Mounjaro the most effective dose for weight loss?
Clinical trials showed weight loss increased with higher doses up to 15 mg, but individual results vary. Some people achieve excellent results at 10 mg or 12.5 mg. Your prescriber will recommend the appropriate dose based on your health, response, and goals rather than assuming higher is always better.
Can I use the MyWeightCheck GLP-1 calculator to predict my weight loss on Mounjaro?
Yes. Our weight loss calculator helps you explore potential outcomes at different tirzepatide doses based on clinical trial data. Remember that results are estimates — individual weight loss varies depending on diet, activity, and personal factors. Discuss realistic expectations with 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.