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
What Is the Maximum Mounjaro Dose in the UK?
Mounjaro (tirzepatide) is a prescription-only weight management injection available in the UK that comes in escalating doses. The maximum dose is 15 mg once weekly, but you don't start at this level. Instead, you begin at 2.5 mg and gradually increase your dose every 4 weeks, moving through intermediate doses of 5 mg, 7.5 mg, 10 mg, 12.5 mg, and finally 15 mg. This gradual titration helps your body adjust and allows your prescriber to monitor how well the medication is working for you. Not everyone reaches the maximum dose — many people find an effective weight loss result at lower doses.
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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 Schedule and Titration in the UK
Mounjaro dosing follows a structured escalation plan:
- Weeks 1–4: 2.5 mg once weekly (starting dose)
- Weeks 5–8+: 5 mg once weekly (first maintenance option)
- Weeks 9–12+: 7.5 mg once weekly
- Weeks 13–16+: 10 mg once weekly
- Weeks 17–20+: 12.5 mg once weekly
- Week 21+: 15 mg once weekly (maximum dose)
Each KwikPen contains 4 pre-filled doses for 4 weeks of treatment. A minimum of 4 weeks must pass at each dose level before your prescriber may increase to the next level. This allows time to assess how well you're responding and monitor for side effects. Your prescriber may decide to keep you on a lower dose if you're experiencing good weight loss and tolerating the medication well — there's no obligation to reach the maximum 15 mg dose. The goal is finding the optimal dose for your individual needs, not necessarily reaching the highest dose available.
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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.
NHS Access and Prescribing Considerations
Access to Mounjaro through the NHS in the UK is available through specialist tier 3 weight management services, though availability varies significantly by region and local Integrated Care Board (ICB) decisions. Your GP can refer you to these services, but waiting lists can be lengthy in many areas. Private prescribing is also available through GPhC-registered online pharmacies following a clinical assessment — this route often provides faster access to treatment. Regardless of whether you receive your prescription through the NHS or privately, your prescriber will follow the same titration schedule and will assess which dose is most appropriate for your circumstances. Regular monitoring and communication with your prescriber throughout your treatment is essential to ensure the dose is working effectively and that you're managing any side effects well.
- 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 a higher Mounjaro dose if I want faster weight loss?
No. UK prescribers follow the 4-week titration schedule for safety reasons. Increasing too quickly increases the risk of side effects and doesn't necessarily lead to better long-term outcomes. Your prescriber will escalate your dose only after assessing your response and tolerance at the current level.
What if I experience side effects at my current Mounjaro dose?
Contact your prescriber immediately. They may pause your dose increase, reduce to a previous dose level, or manage side effects with dietary adjustments. Many side effects improve over time as your body adapts. Never stop taking Mounjaro without medical guidance.
Is 15 mg the right dose for everyone taking Mounjaro in the UK?
No. Many people achieve good weight loss results at doses of 5 mg, 7.5 mg, or 10 mg. Your prescriber will assess your individual response and may recommend staying at a lower dose if you're tolerating it well and losing weight effectively. The maximum dose isn't necessarily the best dose for you.
How do I know which Mounjaro dose I should be on?
Your prescriber will assess your weight loss progress, side effects, and overall health at each 4-week interval. Use our GLP-1 weight loss calculator to estimate potential outcomes at different doses, then discuss results with your prescriber to personalise your treatment plan.
Does the UK BMI calculator help me understand if Mounjaro is right for me?
Yes — calculate your BMI using our free tool above to see if you meet NHS eligibility criteria (BMI 30+ or 27+ with weight-related health conditions). Your GP or prescriber will use this as part of their assessment for whether Mounjaro is appropriate for you.
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.