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 Dose Of Mounjaro?
The maximum dose of Mounjaro (tirzepatide) is 15mg once weekly. Mounjaro is not started at this dose — instead, dosing begins at 2.5mg and increases gradually over several months, with a minimum of four weeks at each dose level before escalation. This stepped approach, called titration, allows your body to adjust to the medication and helps minimise side effects. The full journey from starting dose to maximum typically takes 20 weeks or longer, depending on how you tolerate each dose level. Understanding the dosing schedule helps you plan both your treatment timeline and costs. Use our free GLP-1 weight loss calculator to explore potential outcomes at different dose levels.
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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 Dosing Schedule & Titration Timeline
Mounjaro dosing follows a strict escalation protocol:
- Weeks 1–4: 2.5mg once weekly (starting/adjustment dose)
- Weeks 5–8: 5mg once weekly (first maintenance dose)
- Weeks 9–12: 7.5mg once weekly
- Weeks 13–16: 10mg once weekly
- Weeks 17–20: 12.5mg once weekly
- Week 21 onwards: 15mg once weekly (maximum dose)
Each KwikPen contains four weekly doses. You cannot progress to the next dose level without completing at least four weeks at your current dose — even if you feel ready. This mandatory four-week minimum protects your safety and allows your prescriber to monitor how you're responding. Some people remain on lower doses (5mg, 7.5mg, or 10mg) if they experience side effects or achieve their goals before reaching 15mg. The maximum dose of 15mg is not mandatory — many people find excellent results at intermediate doses.
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.
Accessing Mounjaro In The UK: NHS vs Private Routes
NHS access: Mounjaro is approved by NICE for use within NHS specialist tier 3 weight management services, but availability varies significantly by region (ICB). You typically need a GP referral, and waiting lists can be months to years in many areas. Once approved, the NHS covers the full cost.
Private access: You can obtain Mounjaro through a GPhC-registered online pharmacy following a consultation with a UK-licensed prescriber. This route doesn't require NHS referral and typically costs £129–£320 per month depending on your current dose (higher doses cost more). An online assessment takes 10–15 minutes — the prescriber reviews your medical history, current medications, and BMI or weight-related health conditions to confirm eligibility. If approved, your prescription is dispensed and delivered within 1–2 working days. Try our GLP-1 weight loss calculator to estimate costs and potential outcomes at your target dose.
- 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.
How long does it take to reach the maximum Mounjaro dose of 15mg?
Approximately 20–24 weeks minimum, assuming you progress without delays. You spend four weeks at each dose level, and there are six escalation steps before reaching 15mg. However, many people pause at lower doses if they achieve their weight loss goals earlier or experience side effects they prefer to manage at a stable dose.
Will my GP prescribe Mounjaro at 15mg from the start?
No. Mounjaro must always begin at 2.5mg and titrate upward. Starting at the maximum dose would cause severe side effects (nausea, vomiting, diarrhoea). The gradual escalation allows your body to adapt and helps your prescriber monitor your tolerance and response.
What if I want to stay below the maximum dose of 15mg?
This is entirely reasonable and common. Many people stop escalating once they reach 10mg or 12.5mg if they're satisfied with their weight loss progress and side effects are manageable. Your prescriber will discuss what dose is right for you — there's no requirement to reach 15mg.
Does the cost of Mounjaro change at the maximum 15mg dose?
Yes. Private costs are dose-dependent — the 15mg weekly dose (maximum) is typically the most expensive option, usually around £250–£320 per month depending on the provider. Lower doses (5mg, 10mg) cost proportionally less. NHS cost is covered fully once approved, regardless of dose.
How often do I inject at the maximum dose of 15mg?
Once per week, every seven days. The 15mg KwikPen contains one weekly injection — same frequency as all other Mounjaro doses. You cannot split or divide the dose; each pen delivers the full weekly amount in a single injection, typically into your stomach, thigh, or upper arm.
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.