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 Dose Conversion Chart for UK Adults
Mounjaro (tirzepatide) is prescribed in the UK as a once-weekly injection across a range of doses, from 2.5 mg starting dose up to 15 mg maximum. Understanding how doses escalate, what each dose aims to achieve, and how the NHS and private prescribing differs is essential for anyone considering this prescription-only weight management medication. This guide explains the complete dosing chart, titration schedule, and UK prescribing context to help you have an informed conversation with your GP or prescriber.
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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.
Complete Mounjaro Dosing Schedule and Titration
Mounjaro is administered as a once-weekly KwikPen injection, with each pen containing 4 weekly doses (one month's supply). The medication is titrated—meaning the dose increases gradually every 4 weeks—to allow your body to adapt and to find the dose that works best for you.
- Weeks 1–4: 2.5 mg (starting dose for tolerance)
- Weeks 5–8: 5 mg (first maintenance dose)
- Weeks 9–12: 7.5 mg (optional escalation)
- Weeks 13–16: 10 mg (optional escalation)
- Weeks 17–20: 12.5 mg (optional escalation)
- Week 21 onwards: 15 mg (maximum licensed dose)
Each dose is held for a minimum of 4 weeks before increasing. If you experience significant side effects, your prescriber may recommend staying at a lower dose—there is no requirement to reach 15 mg. In clinical trials, meaningful weight loss occurred at doses of 5 mg and above, so escalation beyond the starting dose is part of the standard protocol, though personalised to your tolerance.
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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.
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NHS Eligibility and Private Access Routes in the UK
In the UK, Mounjaro is available through NHS specialist tier 3 weight management services and through private online prescribing. NHS access requires GP referral to a specialist weight management service; eligibility criteria include BMI of 30 or above, or BMI 27–29.9 with weight-related health conditions such as type 2 diabetes, hypertension, or sleep apnoea. South Asian, Chinese, Black African, and Black Caribbean adults may qualify at lower BMI thresholds (27.5+) due to higher health risk at lower weights. Private access is available without NHS referral following an online clinical assessment with a UK-licensed prescriber. Whatever route you take, a prescriber will assess whether Mounjaro is appropriate for your individual health profile before issuing a prescription.
- 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's the difference between the starting dose and maintenance dose?
The 2.5 mg starting dose is a tolerance dose held for 4 weeks to allow your body to adjust and monitor side effects. The 5 mg dose, reached at week 5, is considered the first maintenance dose—the dose at which clinical trials demonstrated weight loss benefit. You and your prescriber will then decide whether further escalation is needed.
Can I stay on a lower dose if 15 mg causes side effects?
Yes, absolutely. There is no requirement to reach the maximum 15 mg dose. Many people achieve good results at 5 mg, 10 mg, or 12.5 mg. Your prescriber will personalise your dose based on your tolerability and response. Side effects often improve with time, but dose adjustment is always an option.
How do Mounjaro doses compare to Wegovy doses?
Mounjaro and Wegovy are different medications with different potencies. Approximate equivalences are: Mounjaro 5 mg ≈ Wegovy 0.5 mg, Mounjaro 10 mg ≈ Wegovy 1.7 mg, and Mounjaro 15 mg ≈ Wegovy 2.4 mg. However, these are not official conversions—any switch between medications must be managed by your prescriber.
What happens if I miss a dose?
If you miss your weekly injection, you can take it within 4 days of the scheduled time and continue your normal schedule. If more than 4 days have passed, skip that dose and take your next injection on the normally scheduled day. Never double-dose, and ensure at least 72 hours between injections.
Does the NHS prescribe higher doses, or do they stick to lower doses?
NHS prescribing follows the same titration schedule and licensed dose range (2.5 mg to 15 mg). Individual prescribers may recommend different target doses based on patient response and tolerability, but the dose escalation protocol is the same whether you're prescribed through the NHS or privately.
Ready to take control of your weight loss journey?
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