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
Free tracker included with every download this week
Tirzepatide Doses For Weight Loss: UK Dosing Guide
Tirzepatide is a prescription-only weekly weight loss injection available in the UK under the brand name Mounjaro. It works as a GIP receptor and GLP-1 receptor agonist, helping regulate appetite and support weight management alongside diet and physical activity. Understanding the dosing schedule, cost, and how to access tirzepatide in the UK is essential before deciding if this medication is right for you. This guide covers the complete dosing pathway, pricing context, and both NHS and private access routes.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
Tirzepatide Dosing Schedule and NHS vs Private Cost
Tirzepatide dosing starts at 2.5 mg once weekly and increases gradually over weeks, with most users reaching a maintenance dose of 5–15 mg weekly by week 17. Each dose is delivered via a pre-filled KwikPen device and injected once weekly into the stomach, upper thigh, or upper arm. The full dosing pathway spans approximately 20 weeks, though your prescriber may adjust this based on your individual response.
- Week 1–4: 2.5 mg (starting/adjustment dose)
- Week 5–8: 5 mg (first maintenance dose)
- Week 9–12: 7.5 mg (optional escalation)
- Week 13–16: 10 mg (optional escalation)
- Week 17–20: 12.5 mg or 15 mg (maximum dose)
In clinical trials, tirzepatide helped participants lose an average of 15–21% of their body weight — though individual results vary significantly. Private prescription costs in the UK typically range from £129–£320 per month depending on dose and provider, whilst NHS access is free but involves waiting for specialist tier 3/4 services. Calculate your estimated weight loss at different doses using our free GLP-1 weight loss calculator above.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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.
How to Access Tirzepatide in the UK: NHS and Private Routes
NHS access: Tirzepatide (Mounjaro) is approved by NICE for specialist weight management services but is not available through standard GP prescription. You must be referred to a tier 3 or tier 4 NHS weight management service, which typically requires a BMI of 30 or above (or 27+ with weight-related health conditions). Waiting times vary significantly by region and can span many months.
Private access: You can obtain tirzepatide through UK GPhC-registered online pharmacies following an online clinical assessment with a licensed prescriber. This route does not require NHS referral and is often faster, though you pay the full prescription cost. Your prescriber will assess whether tirzepatide is suitable based on your health, medications, and weight loss goals. Use our free BMI calculator to check your starting BMI before your consultation.
- 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 for weight loss?
The starting dose is 2.5 mg once weekly. This is an adjustment dose taken for weeks 1–4 to allow your body to adapt. Most people then progress to 5 mg by week 5, though your prescriber may adjust the pace based on your tolerance and response.
What is the maximum dose of tirzepatide?
The maximum approved dose is 15 mg once weekly. Most people maintain effective weight loss between 5–10 mg weekly. Your prescriber will determine the best dose for you based on your individual results and how you tolerate the medication.
How much does tirzepatide cost on the NHS in the UK?
Tirzepatide is free on the NHS if prescribed through a specialist tier 3/4 weight management service. However, access is limited and waiting lists can be very long depending on your region. Your GP can refer you to your local specialist service to check eligibility and waiting times.
How much does private tirzepatide cost in the UK?
Private tirzepatide costs typically range from £129–£320 per month depending on your dose, with higher doses costing more. Some providers offer discounts for multiple months upfront. Prices vary between GPhC-registered pharmacies, so compare providers before choosing.
Can I switch from tirzepatide to another weight loss injection?
Yes, some people switch to semaglutide (Wegovy) if tirzepatide causes side effects or isn't effective. Any switch must be managed by your prescriber — never change medications without medical guidance. Approximate equivalence is roughly tirzepatide 10 mg to semaglutide 1.7 mg, but conversions are individualised.
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.