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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Tirzepatide Dosing in the UK — Complete Guide
Tirzepatide, the active ingredient in Mounjaro, is prescribed as a once-weekly weight loss injection in the UK. Understanding the tirzepatide dosing schedule is essential for anyone prescribed this GLP-1 receptor agonist and GIP receptor medication. In the UK, tirzepatide dosing follows a structured escalation protocol, starting at a low dose and increasing gradually over several months. This guide explains how tirzepatide dosing works under NHS and private prescribing, what to expect at each dose level, and how your prescriber monitors your response. Our free GLP-1 weight loss calculator can help you understand potential outcomes at different doses.
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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.
How Tirzepatide Dosing Works in the UK
Tirzepatide dosing in the UK follows a standardised escalation schedule designed to help your body adapt to the medication while minimising side effects. The dose increases every 4 weeks, starting at 2.5 mg and going up to a maximum of 15 mg per week.
- 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)
Your prescriber may keep you at any dose for longer if you're experiencing significant benefits or managing side effects well. Tirzepatide is supplied as a weekly injection in a KwikPen device, with each pen containing 4 weeks' worth of doses. Most people stabilise at 10 mg or 15 mg, though individual responses vary considerably. The escalation can be paused or reversed if side effects are troublesome.
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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.
NHS vs Private Tirzepatide Dosing Access in the UK
NHS access to tirzepatide dosing is managed through specialist tier 3 weight management services, typically following referral from your GP. Availability and waiting times vary significantly by region—some areas have waiting lists of several months. Once prescribed through NHS services, the dosing schedule follows NICE guidance and your specialist team monitors your progress at each escalation.
Private tirzepatide prescribing in the UK is available through GPhC-registered online clinics following a clinical assessment. Private prescribers also use the same evidence-based dosing schedule, though they may tailor escalation timing to your individual response. Private access is faster but involves ongoing costs. Either route requires regular check-ins with your prescriber to monitor weight loss and manage side effects. Use our free BMI calculator and progress tracker to monitor your results alongside clinical reviews.
- 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 tirzepatide in the UK?
The standard starting dose of tirzepatide in the UK is 2.5 mg once weekly. This low initial dose helps your body adapt to the medication. Your prescriber will increase the dose every 4 weeks if you're tolerating it well, moving to 5 mg, then 7.5 mg, and so on up to the maximum of 15 mg.
Can my tirzepatide dose be adjusted if I'm experiencing side effects?
Yes. If you're experiencing significant nausea, diarrhoea, or other side effects, your prescriber may pause escalation or reduce your dose. Most side effects improve as your body adjusts. Speak to your GP or prescriber before making any changes—never adjust your own tirzepatide dosing.
What dose of tirzepatide shows the most weight loss in clinical trials?
Clinical trials (SURMOUNT-1) showed average weight loss of approximately 15% at 5 mg, 19.5% at 10 mg, and 20.9% at 15 mg over 72 weeks. However, individual results vary significantly. Some people achieve good results at lower doses; others respond better at higher doses.
How long does tirzepatide dosing escalation take?
Standard tirzepatide dosing escalation takes approximately 20 weeks to reach the maximum 15 mg dose—4 weeks at each dose level. Some prescribers may extend this timeline if side effects occur. You don't have to reach 15 mg; many people find their optimal dose earlier.
Is tirzepatide dosing the same on NHS and private prescriptions?
The dosing schedule is the same—both follow the same escalation protocol. The difference is prescriber access, monitoring frequency, and cost. NHS services are free but may have longer waiting times; private prescribers offer faster access but require payment. Both require clinical assessment before prescribing.
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.