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 Get Mounjaro 15mg in the UK — NHS and Private Routes
Mounjaro (tirzepatide) 15mg is the maximum licensed dose of this prescription-only weight management injection in the UK. You cannot simply "buy" Mounjaro 15mg — it requires a prescription from a licensed healthcare professional following a clinical assessment. This guide explains how to access Mounjaro through both NHS specialist services and private prescribing in the UK, what eligibility criteria apply, and how the 15mg dose works within the standard dose escalation schedule.
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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 Mounjaro 15mg — Eligibility and Tier 3 Services
Mounjaro is available on the NHS through specialist tier 3 weight management services. NICE (the National Institute for Health and Care Excellence) has approved tirzepatide for use within these services for adults who meet eligibility criteria. Access is not through your GP for direct prescription — instead, you must be referred to your regional specialist weight management service by your GP.
- Eligibility for NHS Mounjaro: BMI of 30 kg/m² or above, or BMI 27–29.9 with at least one weight-related health condition (type 2 diabetes, high blood pressure, cardiovascular disease, sleep apnoea, or abnormal blood lipids)
- For South Asian, Chinese, Black African, or Black Caribbean adults: Lower thresholds may apply (BMI 27.5 or above)
- Age requirement: 18 years or older
The 15mg dose is typically reached gradually over 20 weeks, following the standard mounjaro dose titration schedule (2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg). You won't start at 15mg. Reaching maximum dose depends on how your body responds and tolerates each escalation step.
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 Prescribing Route — How to Access Mounjaro 15mg Quickly
If NHS waiting lists in your area are very long, private online prescribing offers faster access to Mounjaro. You can consult with a UK-licensed prescriber remotely, and if clinically appropriate following assessment, receive a prescription that a GPhC-registered pharmacy will dispense. This route bypasses NHS waiting times entirely.
- Online consultation with a licensed UK prescriber (usually £15–30)
- Prescription issued if you meet eligibility criteria
- Dispensed by a regulated pharmacy — costs typically £150–320 per month depending on dose
- Monthly supply (4 pens, 4 weekly injections)
- No NHS referral needed — private route is independent
Both routes require genuine clinical assessment — you cannot obtain prescription tirzepatide without meeting eligibility criteria. Use our free GLP-1 weight loss calculator to explore potential weight loss outcomes at the 15mg dose based on your personal details.
- 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 15mg without a prescription in the UK?
No. Mounjaro is a prescription-only medicine (POM) in the UK. It requires a valid prescription from a licensed prescriber (GP, specialist, or private doctor) following a clinical assessment. You cannot purchase it over-the-counter or without a prescription, regardless of route (NHS or private).
How long does it take to reach the 15mg dose?
The standard schedule takes approximately 20 weeks. You start at 2.5mg and increase by 2.5mg every 4 weeks (Weeks 1–4: 2.5mg; Weeks 5–8: 5mg; Weeks 9–12: 7.5mg; Weeks 13–16: 10mg; Weeks 17–20: 12.5mg; Week 21+: 15mg). Your prescriber may adjust this based on side effects or tolerance.
What is the difference between NHS and private Mounjaro prescriptions?
NHS access is through tier 3 specialist services (referral required, free treatment, potential waiting lists). Private prescribing is faster (online assessment, prescription within days), costs approximately £150–320 monthly depending on dose, and doesn't require an NHS referral. Both are legitimate; the choice depends on waiting times and budget.
Will the NHS pay for Mounjaro 15mg?
Yes, Mounjaro is available on the NHS through specialist tier 3 weight management services. However, not all regions have equal capacity, and waiting lists vary considerably. Some areas have 6–12 month waits, others longer. Contact your local Integrated Care Board (ICB) to check availability in your region.
What side effects should I expect at the 15mg dose?
Common side effects include nausea, diarrhoea, constipation, and loss of appetite — most people experience some nausea early on, which usually improves within weeks. At higher doses, some people report fatigue or headaches. Serious side effects are rare but include severe stomach pain (possible pancreatitis) — seek immediate medical attention if this occurs. Calculate your personal weight loss projection using our free GLP-1 weight loss calculator, which also helps you understand the dose escalation process.
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.