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
Who Makes Mounjaro and How to Access It in the UK
Mounjaro (tirzepatide) is manufactured by Eli Lilly and Company, a global pharmaceutical manufacturer. In the UK, this prescription-only weight management injection is available through both NHS specialist services and private online prescribing. NICE has approved tirzepatide for use within NHS tier 3 weight management services, though availability varies significantly by region. Understanding the maker, NHS pathway, and eligibility criteria can help you explore your options for accessing this medication through your GP or a licensed prescriber.
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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 and NICE Approval for Mounjaro
Eli Lilly's tirzepatide (Mounjaro) received NICE approval for use within NHS specialist weight management services in 2024. Access is through tier 3 multidisciplinary weight management services, typically following referral from your GP. You may be eligible if you have a BMI of 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. The KwikPen device comes pre-filled with once-weekly injections starting at 2.5 mg and titrating up to 15 mg over several months. NHS availability depends on your integrated care board (ICB) region, and waiting times can be lengthy in many areas. Use our free BMI calculator above to check whether you might meet NHS eligibility thresholds, and discuss referral options with your GP.
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 How to Compare with Wegovy
If NHS waiting lists are long in your area, Mounjaro is also available privately through GPhC-registered online pharmacies following a clinical assessment with a UK-licensed prescriber. Private costs typically range from £129 to £320 per month depending on dose. When comparing options, remember that Mounjaro uses a dual GIP and GLP-1 mechanism (unlike Wegovy, which is a single GLP-1 agonist), though both are once-weekly injections. Clinical trials showed Mounjaro helped participants lose an average of 15–21% body weight, though individual results vary significantly. Your prescriber will assess whether Mounjaro is suitable based on your health history, medications, and personal circumstances.
- 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 made by Novo Nordisk or Eli Lilly?
Mounjaro is made by Eli Lilly and Company. You may be thinking of Wegovy (semaglutide), which is made by Novo Nordisk. Both are GLP-1-type medications licensed for weight management in the UK, but they come from different manufacturers and have slightly different mechanisms.
Can I get Mounjaro on the NHS in the UK?
Yes, NICE has approved tirzepatide for NHS specialist weight management services (tier 3). Access is through referral from your GP to a multidisciplinary weight management team. Eligibility requires a BMI of 30 or above, or 27–29.9 with weight-related health conditions. Availability and waiting times vary by region.
What dose does Mounjaro start at?
Mounjaro starts at 2.5 mg once weekly. Your prescriber will increase the dose every 4 weeks, moving through 5 mg, 7.5 mg, 10 mg, 12.5 mg, and up to 15 mg as your maximum dose. Dose titration helps your body adjust and manage side effects.
How much does Mounjaro cost privately in the UK?
Private Mounjaro typically costs between £129 and £320 per month, depending on your dose and the provider. Prices vary between different online prescribing services and pharmacies, so it's worth comparing. NHS access is free if you're eligible through specialist services.
Should I choose Mounjaro or Wegovy?
Both are licensed for weight management in the UK. Mounjaro (Eli Lilly's tirzepatide) is a dual GIP/GLP-1 agonist; Wegovy (Novo Nordisk's semaglutide) is GLP-1 only. Clinical trials showed similar average weight loss, though your prescriber will recommend the most suitable option based on your individual health profile, medications, and circumstances.
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.