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 (brand name Mounjaro) is a prescription-only weekly weight loss injection available in the UK through both NHS specialist services and private online prescribing. If you're considering this dual GIP receptor and GLP-1 receptor agonist medication, you'll need to understand the two routes to access it: NHS referral through specialist weight management services, or a private clinical assessment followed by prescription. This guide explains the cost, eligibility, and realistic timelines for both pathways.
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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.
Private Tirzepatide Costs & Access in the UK
In the UK, private tirzepatide prescriptions typically cost between £129 and £320 per month, depending on the dose and provider. Prices generally reflect the injection strength: lower starting doses (2.5 mg) are cheaper, whilst higher maintenance doses (10–15 mg) cost more. You'll receive your Mounjaro KwikPen pre-filled injection pen through a GPhC-registered pharmacy after a clinical assessment with a UK-licensed prescriber.
- Starting dose (2.5 mg): approximately £129–£160/month
- Mid-range doses (5–7.5 mg): approximately £180–£240/month
- Higher doses (10–15 mg): approximately £260–£320/month
Private access does not require NHS referral and you can begin the process within days. Most private providers offer ongoing prescriber support and dose adjustments. Prices vary between providers, so it's worth comparing multiple options before committing.
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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: Timeline & Eligibility
NHS Route: Free once prescribed, but requires referral to tier 3 specialist weight management services. Waiting times vary dramatically by region—some areas have waiting lists of 6–18 months. Eligibility is the same as private: BMI ≥30, or BMI 27–29.9 with weight-related health conditions.
Private Route: You'll complete an online health questionnaire, have a consultation with a prescriber (usually within 24–48 hours), and if approved, your prescription is sent to a pharmacy for dispatch. No GP referral needed. You can start within days rather than months, but you pay out of pocket. Both routes require a genuine clinical assessment—you won't be prescribed this weekly weight loss injection without proper health screening.
- 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.
Can I get tirzepatide on the NHS?
Yes, tirzepatide (Mounjaro) is available on the NHS through tier 3 specialist weight management services. You'll need a GP referral and must meet eligibility criteria (BMI ≥30, or 27–29.9 with weight-related health conditions). Waiting times vary by region, from a few months to over a year. Availability depends on your local integrated care board.
How much does tirzepatide cost privately?
Private tirzepatide typically costs £129–£320 per month depending on dose. Lower starting doses (2.5 mg) start around £129–£160, whilst higher maintenance doses (10–15 mg) cost £260–£320. You pay per month for each KwikPen prescription. Prices vary between providers—compare options before starting.
How long does it take to get a private tirzepatide prescription?
Private access is much faster than NHS. After completing your health questionnaire, you'll usually have a prescriber consultation within 24–48 hours. If approved, your prescription is sent to a pharmacy and dispatched within 1–2 days. You could start your treatment within days rather than waiting months for NHS referral.
What do I need to do to buy tirzepatide privately?
Complete an online health questionnaire about your weight, medical history, and current medications. A UK-licensed prescriber will review your information and decide if you're eligible. If approved, they'll issue a prescription to a GPhC-registered pharmacy, which dispenses and delivers your Mounjaro KwikPen. You'll pay the agreed cost per month.
Is tirzepatide the same as Mounjaro?
Yes—tirzepatide is the active ingredient, and Mounjaro is the brand name. It's a once-weekly GIP receptor and GLP-1 receptor agonist injection for weight management. Starting doses begin at 2.5 mg, escalating to a maximum of 15 mg weekly. Both NHS and private providers prescribe it under the brand name Mounjaro.
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.