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 to Buy Tirzepatide in the UK
Tirzepatide, marketed as Mounjaro in the UK, is a prescription-only weight loss injection that may help adults manage their weight through a dual GIP and GLP-1 receptor agonist mechanism. You cannot simply buy tirzepatide over the counter—it requires a clinical assessment and prescription from a UK-licensed healthcare provider. This guide explains your options for accessing tirzepatide in the UK, whether through NHS specialist services or private prescribing, including eligibility criteria and what the process involves.
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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.
NHS Access to Tirzepatide in the UK
NHS access to tirzepatide (Mounjaro) is through specialist tier 3 or 4 weight management services. NICE has approved tirzepatide for use within these specialist services for eligible adults. To access NHS tirzepatide, you typically need to be referred by your GP to a specialist weight management service in your area. Availability varies significantly by region—some integrated care boards (ICBs) have established tirzepatide pathways, whilst others may have limited access or lengthy waiting lists spanning several months or even years.
- You must meet NHS eligibility criteria: BMI of 30 kg/m² or above, or BMI 27–29.9 kg/m² with weight-related health conditions
- For South Asian, Chinese, Black African, or Black Caribbean adults, lower BMI thresholds may apply (27.5 kg/m² and above)
- Your GP will assess your suitability and make a referral to your local specialist service
- The specialist team will conduct a full clinical assessment before prescribing
- NHS tirzepatide is free once prescribed through the NHS
Contact your local NHS weight management service or ask your GP about availability in your area. Waiting times can be considerable, so it's worth enquiring early.
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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.
Private Access to Tirzepatide in the UK
Private tirzepatide prescriptions are available through UK-licensed online prescribers and GPhC-registered pharmacies. This route does not require an NHS referral and typically offers faster access than NHS services. A UK-based, licensed prescriber will conduct an online clinical assessment to determine whether tirzepatide is suitable for you. If approved, a prescription is issued and your tirzepatide is dispensed by a registered pharmacy. Private costs vary by dose (from approximately £129–£320 per month depending on the dose and provider). Use our free GLP-1 weight loss calculator above to explore projected weight loss at different tirzepatide doses, helping you understand whether this medication aligns with your goals before pursuing a prescription.
Whichever route you choose, tirzepatide is started at a low dose (2.5 mg) and gradually increased weekly based on tolerance and response. The maximum dose is 15 mg once weekly. Track your progress throughout your treatment using our free progress tracker, which allows you to log weekly weight changes and monitor trends alongside your tirzepatide dose adjustments.
- 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.
Do I need a prescription to buy tirzepatide in the UK?
Yes, tirzepatide is a prescription-only medicine in the UK. You cannot buy it without a prescription from a UK-licensed prescriber. Access is either through NHS specialist weight management services or private prescribing via a licensed UK healthcare provider.
Can my GP prescribe tirzepatide directly?
In most cases, your GP will refer you to a specialist tier 3 or tier 4 weight management service. GPs typically do not prescribe tirzepatide in primary care—specialist assessment is usually required first, though this varies slightly by region.
How much does tirzepatide cost privately in the UK?
Private tirzepatide costs typically range from £129–£320 per month depending on the dose. Lower doses (2.5–5 mg) are at the lower end, whilst higher maintenance doses (10–15 mg) cost more. Prices vary by provider, so it's worth comparing.
What are the eligibility criteria for tirzepatide in the UK?
You're generally eligible if you have a BMI of 30 kg/m² or above, or BMI 27–29.9 kg/m² with at least one weight-related health condition (type 2 diabetes, high blood pressure, sleep apnoea, or cardiovascular disease). Lower thresholds apply for certain ethnic backgrounds.
How long does it take to get tirzepatide on the NHS?
NHS waiting times vary significantly by region, ranging from several weeks to over a year in some areas. Private access is typically faster—often within 1–2 weeks of your initial consultation. Contact your local specialist weight management service for a realistic timeframe in your area.
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.