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
Mounjaro Guidance: NHS and UK Prescribing Information
Mounjaro (tirzepatide) is a prescription-only weight management injection now available in the UK through both NHS specialist services and private prescribing routes. This guide covers NHS eligibility criteria, NICE approval status, how the medication works, and the practical steps to access it. Whether you're considering Mounjaro through your GP or exploring private options, understanding the UK prescribing landscape helps you make informed decisions about weight management. Use our free BMI calculator to check your eligibility status based on current UK guidance.
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.
NHS Eligibility and Access Routes for Mounjaro
NHS prescribing eligibility for Mounjaro (tirzepatide):
- BMI of 30 kg/m² or above (obesity), OR
- BMI of 27–29.9 kg/m² with at least one weight-related health condition such as type 2 diabetes, prediabetes, hypertension, dyslipidaemia, obstructive sleep apnoea, or cardiovascular disease
- For South Asian, Chinese, Black African, and Black Caribbean adults: lower thresholds apply (BMI 27.5 or above)
NICE has approved tirzepatide for NHS use within specialist tier 3 and tier 4 weight management services. Important: This is not standard GP prescription — access is through specialist multidisciplinary weight management teams, typically following referral from your GP. Waiting times and availability vary significantly by region (ICB). Many areas have substantial waiting lists. The NHS considers Mounjaro alongside other weight management approaches, including lifestyle intervention and other medications such as Wegovy.
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 Access and NHS vs Private Routes
Private prescribing route: Mounjaro is available through GPhC-registered online pharmacies following a clinical assessment by a UK-licensed prescriber. Private access does not require NHS referral or waiting for tier 3 services. Costs typically range from £180–£320 per month depending on dose. NHS vs private comparison: NHS access is free at point of use but involves waiting lists and regional variation. Private access is faster but costs apply. Both routes require a valid prescription and clinical assessment to ensure the medication is appropriate for you. Your GP can advise on NHS eligibility and timescales in your area.
- 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 difference between Mounjaro and Wegovy in the UK?
Both are prescription-only weight management injections licensed in the UK. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist; Wegovy (semaglutide) is a GLP-1 agonist only. Mounjaro typically reaches a maximum dose of 15 mg once weekly, while Wegovy maxes at 2.4 mg weekly. Clinical trials showed Mounjaro produced average weight loss of approximately 15–21%, compared to Wegovy at around 15%. Individual results vary significantly. Your prescriber will assess which is more suitable for you.
Can I get Mounjaro on the NHS in the UK?
Yes, NICE has approved tirzepatide for NHS use, but access is through specialist tier 3 weight management services, not routine GP prescription. You typically need referral from your GP to a multidisciplinary weight management team. Availability and waiting times vary by region. If NHS waiting times are long in your area, private prescribing is an alternative route that does not require NHS referral.
What is the starting dose of Mounjaro and how does dose titration work?
The starting dose is 2.5 mg once weekly for the first 4 weeks. The dose then increases by 2.5 mg every 4 weeks (5 mg weeks 5–8, 7.5 mg weeks 9–12, and so on) up to a maximum of 15 mg weekly. Your prescriber will assess your response and tolerability at each stage. Most people remain on 10 mg or 15 mg as a maintenance dose. The KwikPen pre-filled injection device contains 4 doses (one month's supply).
What health conditions make me eligible for Mounjaro on the NHS?
Beyond BMI thresholds, you may be eligible if you have type 2 diabetes, prediabetes, high blood pressure, abnormal blood fats (dyslipidaemia), obstructive sleep apnoea, or a history of heart attack or stroke. These weight-related comorbidities can qualify you for treatment at a lower BMI (27–29.9) under NHS guidelines. Your GP can assess whether you meet criteria and whether referral to specialist services is appropriate.
How should I store Mounjaro KwikPens and what if I miss a dose?
Unopened pens must be refrigerated at 2–8°C and kept in the original carton. After first use, pens can be stored at room temperature (below 30°C) for up to 30 days, then discarded. If you miss a dose within 4 days, inject as soon as you remember and continue your normal weekly schedule. If more than 4 days have passed, skip that dose and take your next injection on the normal scheduled day. Never take a double dose.
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.