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 Often Do You Take Mounjaro? UK Dosing Guide
Mounjaro (tirzepatide) is taken as a once-weekly injection, not daily. The dose starts low and gradually increases every 4 weeks over approximately 4–5 months. This article explains the complete UK dosing schedule, what each dose achieves, and how to access Mounjaro through both NHS specialist services and private prescription routes in the UK.
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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 Dosing Schedule: From Start to Maintenance
Mounjaro is administered as a once-weekly injection using a pre-filled KwikPen device. Each pen contains 4 doses (a 4-week supply). The dosing schedule follows a strict titration process, meaning your dose increases gradually rather than starting at the maximum strength.
- 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 onwards: 15 mg once weekly (maximum dose)
You must spend at least 4 weeks on each dose before increasing. This gradual escalation allows your body to adjust and helps minimise side effects like nausea. Not everyone needs to reach the 15 mg maximum—your prescriber will recommend the right maintenance dose for you based on your response and tolerance. Our GLP-1 weight loss calculator can help you understand potential outcomes at different dose levels.
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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.
Mounjaro Cost in the UK: NHS vs Private Access
NHS access: Mounjaro is available through NHS specialist tier 3 weight management services, but availability varies significantly by region. Waiting lists can extend many months. Your GP must refer you to your local integrated care board's specialist weight management service.
Private prescription cost: Via private online prescribing, Mounjaro typically costs £129–£299 per month depending on the dose and provider. This usually includes the online clinical assessment and prescription. Costs are higher for maximum doses (15 mg) and lower for starting doses (2.5 mg). Private access doesn't require NHS referral—you complete an online consultation with a UK-licensed prescriber who assesses your eligibility. The KwikPen, prescription, and monthly delivery are all included. Using our BMI calculator, you can check your eligibility threshold before booking a private consultation.
Storage and disposal: Unopened pens must be refrigerated (2–8°C). After first use, you can store your pen at room temperature for up to 30 days. Always dispose of your pen safely in a sharps bin—your pharmacy can provide one. Never share your pen with anyone else, even if the needle is changed. If you miss a dose by 4 days or less, inject as soon as you remember and resume your normal weekly schedule. If more than 4 days have passed, skip that dose and inject on your normally scheduled day. Minimum time between injections is 72 hours.
- 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.
Is Mounjaro a daily injection?
No. Mounjaro is administered as a once-weekly injection using a KwikPen device. Each pen contains 4 weeks of doses. You inject the same day each week—many people choose a convenient day like Monday morning.
How much does Mounjaro cost in the UK privately?
Private Mounjaro costs approximately £129–£299 per month depending on your dose. The 2.5 mg starting dose is cheaper; the 15 mg maximum dose is more expensive. This typically includes the online assessment, prescription, pen, and delivery.
Can I get Mounjaro on the NHS in the UK?
Yes, Mounjaro is available through NHS specialist weight management services (tier 3). You need a GP referral to your local service. However, availability and waiting times vary significantly by region—some areas have long waiting lists.
What happens if I miss a weekly Mounjaro injection?
If you miss a dose by 4 days or less, inject as soon as you remember and resume your normal weekly schedule. If more than 4 days have passed, skip that dose and continue on your normal day the following week. Never inject twice in one week to make up for a missed dose.
How long does it take to reach the maximum Mounjaro dose?
It takes approximately 20 weeks (5 months) to progress from the starting 2.5 mg dose to the maximum 15 mg dose, because you spend at least 4 weeks on each step. Your prescriber may decide you don't need to increase further if you're achieving good results at a lower dose.
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.