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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Mounjaro Dosing Chart — UK Prescribing Guide
Mounjaro (tirzepatide) is prescribed in the UK as a once-weekly injection with a standard 4-week dose escalation schedule. Starting at 2.5 mg, the dose increases gradually up to a maximum of 15 mg per week, with each dose held for at least 4 weeks before escalation. This guide explains the full dosing chart, how the dose titration works in UK clinical practice, and what you can expect at each stage of treatment.
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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 and Dose Escalation
Mounjaro tirzepatide dosing follows a standardised UK escalation pathway designed to help your body adjust and minimise side effects. Each KwikPen contains 4 weeks' supply of your current dose.
- 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)
Your prescriber will assess your progress at each stage. Dose increases only occur if you've tolerated the previous dose well for at least 4 weeks. Some patients remain on lower doses (5 mg, 7.5 mg, or 10 mg) if they achieve good results or experience side effects. Individual responses vary significantly — there is no one-size-fits-all dose. Your GP or specialist will guide escalation based on your personal tolerance and weight loss response.
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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.
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Mounjaro vs Wegovy Dosing and NHS Access in the UK
Mounjaro and Wegovy (semaglutide) are both once-weekly injections but use different dosing schedules. Wegovy starts at 0.25 mg and escalates to a maximum of 2.4 mg, whereas Mounjaro's higher maximum dose (15 mg) reflects its dual GIP and GLP-1 mechanism. Both require NHS specialist referral for NHS access through NICE-approved tier 3 weight management services, though availability varies by region and waiting times can be lengthy. Private prescribing through UK-licensed prescribers offers faster access but requires a clinical assessment. Use our GLP-1 weight loss calculator to estimate potential outcomes, and consult your GP about eligibility and the best route for you.
- 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.
What is the starting dose of Mounjaro in the UK?
The standard starting dose is 2.5 mg once weekly. This initial dose is held for 4 weeks to allow your body to adjust. After 4 weeks, if tolerated well, most patients escalate to 5 mg. Your prescriber may keep you on 2.5 mg longer if you experience significant side effects.
How long does each Mounjaro dose last before increasing?
Each dose is held for at least 4 weeks before escalation. This means you use one KwikPen (containing 4 weeks of doses) before moving to the next strength. Escalation is not automatic — your prescriber assesses your response and tolerability at each stage.
What is the maximum Mounjaro dose in the UK?
The maximum licensed dose is 15 mg once weekly. This is reached after approximately 20 weeks of escalation from the starting 2.5 mg dose. Not all patients require or tolerate the maximum dose — many achieve good results at 5 mg, 7.5 mg, or 10 mg.
Is Mounjaro available on the NHS in the UK?
Yes, tirzepatide (Mounjaro) is approved by NICE for use within NHS specialist weight management services (tier 3). Access requires referral from your GP and assessment by a specialist team. However, NHS availability and waiting times vary significantly by region, and demand currently exceeds capacity in many areas.
Can I switch from Mounjaro to Wegovy or another GLP-1 medication?
Switching between weight loss medications requires prescriber guidance. Mounjaro and Wegovy are not directly equivalent — Mounjaro is a dual GIP/GLP-1 agonist while Wegovy is GLP-1 only. Any change in medication must be managed by your prescriber to ensure safe transition and appropriate dosing.
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