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
Buying Mounjaro in the UK: Your Complete Guide
If you're considering Mounjaro (tirzepatide) for weight management in the UK, you have two main routes: NHS specialist services or private online prescribing. Both require a clinical assessment from a licensed prescriber. This guide explains how to access Mounjaro in the UK, what to expect, how it compares to Wegovy, and what the costs and eligibility criteria are. Understanding your options helps you make an informed decision about whether this prescription weight loss injection is right for you.
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.
Mounjaro vs Wegovy: Key Differences When Buying in the UK
Mounjaro (tirzepatide) and Wegovy (semaglutide) are both prescription-only weight loss injections available in the UK, but they work differently. Mounjaro is a dual GIP and GLP-1 receptor agonist, meaning it activates two natural hormone pathways, whilst Wegovy is a GLP-1 agonist only. In clinical trials, Mounjaro users lost an average of 15–21% of body weight using the SURMOUNT protocol, compared to approximately 15% with Wegovy in the STEP trials — though individual results vary significantly. Mounjaro comes in a KwikPen format with doses from 2.5mg to 15mg once weekly, whilst Wegovy uses an auto-injection pen with doses up to 2.4mg. Both require a reduced-calorie diet and increased physical activity to be effective. Your prescriber will assess which medication suits your individual health profile, medical history, and weight loss goals. Cost varies by dose and provider, but both typically range from £129–£320 monthly on the private market. Neither medication is a substitute for lifestyle changes.
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.
How to Access Mounjaro: NHS vs Private Routes in the UK
NHS route: Mounjaro is approved by NICE for specialist weight management services. You'll need a GP referral to a tier 3 or tier 4 specialist service. Availability and waiting times vary significantly by region (ICB). Some areas have very long waiting lists.
Private route: GPhC-registered online pharmacies offer Mounjaro following an online clinical assessment with a UK-licensed prescriber. This doesn't require NHS referral and is typically faster. You'll complete a health questionnaire, and a prescriber will assess your eligibility based on BMI, medical history, and weight-related conditions. If approved, your prescription is dispensed and delivered. Always verify the pharmacy is GPhC-registered before purchasing any prescription medication.
- 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's the difference between Mounjaro and Wegovy?
Both are once-weekly weight loss injections available in the UK. Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist; Wegovy (semaglutide) is a GLP-1 agonist only. Clinical trial data shows similar average weight loss (15–21% for Mounjaro, ~15% for Wegovy), but individual results vary. Your prescriber will help you choose based on your health profile.
Can I get Mounjaro on the NHS in the UK?
Yes, NICE has approved tirzepatide (Mounjaro) for use in NHS specialist weight management services. You'll need a GP referral to a tier 3 or 4 service. Access and waiting times vary by region. Private access is available without NHS referral but involves cost.
How much does Mounjaro cost in the UK privately?
Private Mounjaro costs typically range from £129–£320 per month depending on dose (2.5mg to 15mg). Prices vary by provider. Each pen contains four weekly doses. Always check you're using a GPhC-registered pharmacy before purchasing.
Who can buy Mounjaro in the UK?
Adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions (type 2 diabetes, hypertension, sleep apnoea), may be eligible. South Asian, Chinese, Black African, or Black Caribbean adults may qualify at lower BMI thresholds. A prescriber must assess your individual suitability.
How do I know if Mounjaro or Wegovy is right for me?
Both require a clinical assessment. A prescriber will review your medical history, current medications, BMI, and weight loss goals. Neither is suitable if you're pregnant, breastfeeding, or under 18. Use our free BMI calculator to check your current BMI, then discuss options with your GP or a private prescriber.
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.