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 Mounjaro Online in the UK
Mounjaro (tirzepatide) is a prescription-only weight management injection available in the UK through two main routes: NHS specialist services and private online prescribing. Understanding your options, eligibility criteria, and how the prescribing process works can help you make an informed decision about whether this medication is right for you. This guide explains both pathways and what to expect at each stage.
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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 Route: Eligibility and Specialist Services
Accessing Mounjaro through the NHS requires referral to a tier 3 specialist weight management service, typically arranged by your GP. You'll need a BMI of 30 kg/m² or above, or 27–29.9 kg/m² with a weight-related health condition such as type 2 diabetes, hypertension, or cardiovascular disease. South Asian, Chinese, Black African, and Black Caribbean adults may be eligible at lower BMI thresholds due to higher health risks at these weights.
- Your GP assesses your suitability and refers you to a specialist service
- Specialist services provide comprehensive assessment including medical history and comorbidities
- If approved, Mounjaro is prescribed through the NHS at no cost to you
- Regional availability varies significantly — some areas have lengthy waiting lists
- NICE has approved tirzepatide (Mounjaro) for use within specialist weight management services, supporting NHS prescribing where resources allow
NHS prescription includes regular clinical monitoring, dose escalation support, and dietary guidance as part of a multidisciplinary approach.
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.
Private Route: Online Prescribing and Pharmacies
Private access to Mounjaro is available through UK-licensed prescribers via online consultation without requiring NHS referral. A GPhC-registered online pharmacy dispenses your KwikPen following clinical assessment. The private route typically costs between £129–£320 per month depending on your dose.
- Complete an online consultation with a UK-licensed prescriber
- Prescriber assesses eligibility and medical history
- If approved, prescription is issued and dispensed by a registered pharmacy
- You'll need to manage your own monitoring and dose escalation schedule
- Cost varies by dose: lower starting doses (2.5 mg) cost less than maintenance doses (15 mg)
Use our GLP-1 weight loss calculator to explore potential outcomes at different doses, and our BMI calculator to check your current status and eligibility starting point.
- 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 buy Mounjaro online in the UK without a prescription?
No. Mounjaro is a prescription-only medication in the UK. You must have a valid prescription from a UK-licensed prescriber before any pharmacy can dispense it. Online prescribers can issue prescriptions after assessing your suitability through an online consultation, but you cannot bypass the prescription requirement.
How long does it take to get Mounjaro through the NHS?
NHS waiting times vary significantly by region. Some specialist services have waiting lists of several months to over a year, depending on demand and local capacity. Private prescribing typically offers faster access, with prescriptions issued within days of online consultation, though this depends on individual prescriber availability.
What's the difference between buying Mounjaro privately versus through the NHS?
NHS access is free but involves GP referral and specialist assessment with longer waiting times. Private access is faster and doesn't require NHS referral, but costs £129–£320 per month. NHS includes multidisciplinary support; private access requires self-management of monitoring and dose escalation. Both routes require a valid prescription.
Is Mounjaro the same as Wegovy for weight loss?
Both are weight loss injections, but Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. Clinical trials show Mounjaro may produce slightly greater average weight loss, though individual results vary significantly. Your prescriber will advise which is appropriate for you.
What happens if I'm not eligible for NHS Mounjaro?
You can explore private prescribing if you don't meet NHS eligibility criteria or prefer faster access. Private prescribers assess eligibility independently, though criteria are broadly similar. You can also discuss alternative weight management approaches with your GP, including diet, exercise, and other support services available through the NHS.
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.