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
Do You Need A Prescription For Mounjaro In The UK?
Yes, Mounjaro (tirzepatide) is a prescription-only medicine in the UK — you cannot buy it over-the-counter. Access is through two routes: NHS specialist weight management services or private prescription following an online clinical assessment. Both require a licensed UK prescriber to assess your eligibility before issuing a prescription. Check your BMI and health needs using our free BMI calculator to understand if you might be eligible for treatment.
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.
How To Access Mounjaro: NHS vs Private Routes
NHS access: Mounjaro is available through NHS tier 3 specialist weight management services following NICE approval. You'll need a referral from your GP, who will assess whether you meet eligibility criteria: BMI of 30 or above, or 27–29.9 with weight-related health conditions like type 2 diabetes, high blood pressure, or cardiovascular disease. NHS availability varies significantly by region — some areas have specialist services with long waiting lists, whilst others may have limited access. Your GP can advise what's available locally. Private access: Private prescription requires an online consultation with a UK-licensed prescriber registered with the GMC. Following clinical assessment, if approved, a prescription is issued and dispensed by a GPhC-registered pharmacy. Private Mounjaro costs vary by dose but typically range from £129–£320 per month depending on the dose level and provider. Unlike the Mounjaro KwikPen that NHS prescriptions use, availability and pricing structures differ between private providers.
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.
What Happens During A Private Clinical Assessment?
An online consultation typically takes 10–15 minutes and asks about your medical history, current medications, weight, height, and any existing health conditions. The prescriber will assess whether Mounjaro is suitable for you based on eligibility criteria and contraindications (e.g., pregnancy, pancreatitis history, gallbladder disease). You'll be asked about your lifestyle, diet, and exercise habits — Mounjaro works alongside reduced-calorie diet and physical activity, not instead of them. If approved, a prescription is issued electronically to a pharmacy. If not approved, the prescriber will explain why and may suggest alternative approaches. The entire process is typically completed within 24–48 hours. You can then track your weight loss journey using our free progress tracker as your prescription arrives.
- 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.
Is Mounjaro available on the NHS in my area?
Mounjaro is approved by NICE for NHS use, but availability depends on your local Integrated Care Board (ICB). Ask your GP whether your region's tier 3 weight management service prescribes tirzepatide. Some areas may have long waiting lists or may not yet have implemented the service. Your GP can check local eligibility and waiting times.
How much does Mounjaro cost privately per month?
Private Mounjaro costs typically range from £129–£320 per month depending on the dose. Starting doses (2.5 mg) are usually cheaper; higher maintenance doses (15 mg) cost more. Prices vary slightly between providers. Some offer monthly payment plans or bulk discounts. Always confirm the total cost including delivery before starting treatment.
What's the difference between NHS and private Mounjaro prescriptions?
Both are identical tirzepatide medications. The difference is access speed and availability. NHS requires GP referral and may involve waiting lists, but costs nothing. Private requires online assessment and costs monthly fees, but is typically faster (24–48 hours). Both require ongoing clinical support and monitoring by a licensed prescriber.
Can my GP prescribe Mounjaro privately if I ask?
Some GPs offer private prescribing services, but most NHS GPs cannot issue private prescriptions for weight management medications due to NHS commissioning rules. Private prescriptions must come from a prescriber registered specifically for private practice. Your GP can advise whether they offer private weight management consultations.
Do I need to pay for a follow-up assessment with private prescription?
Most private providers include follow-up consultations as part of the service, though this varies. Some charge per consultation (typically £20–£50), whilst others include them in the monthly fee. Confirm what follow-up support is included — you'll need periodic check-ins to monitor side effects, assess progress, and adjust doses. Our GLP-1 weight loss calculator can help estimate expected outcomes between consultations.
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.