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 Mounjaro Dose Increases Work in the UK
Mounjaro (tirzepatide) is prescribed using a gradual dose escalation schedule rather than starting at maximum strength. In the UK, treatment begins at 2.5 mg per week and increases in steps every four weeks, up to a maximum of 15 mg per week. This tiered approach, called titration, allows your body to adjust to the medication and helps minimise side effects. Your prescriber will manage the timing of each dose increase based on your response and tolerability. Understanding the dosing schedule helps you prepare for what to expect throughout your treatment journey.
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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 UK Dose Escalation Schedule
The standard Mounjaro dosing schedule in the UK follows this progression:
- Weeks 1–4: 2.5 mg once weekly (starting dose)
- Weeks 5–8: 5 mg once weekly
- 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 dose is delivered via a pre-filled Mounjaro KwikPen for once-weekly injection. A minimum of 4 weeks is required at each dose level before increasing to the next step. Your prescriber may adjust this timeline based on your tolerance and response. Not everyone reaches the maximum dose — some individuals achieve their weight management goals at lower doses. Dose increases should never be rushed, as the body benefits from time to adapt. If you experience significant side effects at any dose level, discuss this with your prescriber before escalating.
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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.
When and Why Doses Increase
Dose increases are timed to allow your body to adjust and for side effects to settle. The four-week intervals are evidence-based — this duration lets most people tolerate each new level comfortably. Your prescriber decides if and when you progress, based on factors including your tolerance, weight loss response, and any medical conditions. Some people need to stay at a lower dose longer, or may not need to increase further. If nausea or other side effects persist after four weeks at a given dose, your prescriber may delay escalation or keep you at that level. Dose timing is personalised — this is not a "one-size-fits-all" progression. Our GLP-1 weight loss calculator can help you understand projected outcomes at different dose levels throughout your 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.
Can I skip dose levels and jump to a higher Mounjaro dose?
No. UK guidelines and best practice require a minimum 4 weeks at each dose before increasing. Skipping levels increases the risk of severe side effects like nausea and vomiting. Your prescriber will not authorise faster escalation. Each step is designed to let your body adapt safely.
What if I have side effects during Mounjaro dose increase?
Tell your prescriber immediately. Common side effects (nausea, constipation, stomach pain) often improve over days or weeks at the same dose. You may stay at your current dose longer, reduce to a previous dose, or stop temporarily. Never adjust doses yourself — always discuss with your prescriber first.
Is the maximum Mounjaro dose 15 mg for everyone in the UK?
Yes, 15 mg is the maximum licensed dose for tirzepatide in the UK. Some people achieve good weight management results at lower doses (5 mg, 10 mg, or 12.5 mg) and may not need to escalate further. Your prescriber will assess whether you should increase based on your response.
How long does the full Mounjaro dose increase cycle take?
Following the standard schedule from 2.5 mg to the maximum 15 mg takes approximately 20 weeks (around 5 months). However, your actual timeline may differ — you might stay at a lower dose longer, or progress slower if side effects occur. This is normal and personalised to your individual response.
How does Mounjaro dose titration compare to Wegovy dosing?
Wegovy (semaglutide) also uses dose titration but over a longer timeframe and with smaller dose increments (0.25 mg up to 2.4 mg over 17 weeks). Mounjaro dose increases are larger and faster due to the different drug mechanism. Both approaches allow the body to adapt safely. Compare doses using our BMI calculator alongside clinical guidance from 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.