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 Is It Prescribed in the UK?
Mounjaro (tirzepatide) is manufactured by Eli Lilly and Company, a major global pharmaceutical manufacturer. In the UK, Mounjaro is a prescription-only weight management injection licensed by the MHRA (Medicines and Healthcare products Regulatory Agency) with Black Triangle ▼ status, meaning it receives additional monitoring. It's available through NHS specialist tier 3 weight management services or private online prescribing following clinical assessment. Understanding who makes Mounjaro, how it works, and your eligibility helps you make informed decisions about weight management options.
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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.
Eli Lilly, MHRA Approval, and UK Prescribing Routes
Eli Lilly and Company is the pharmaceutical manufacturer behind Mounjaro (tirzepatide). The company developed tirzepatide as a dual GIP and GLP-1 receptor agonist, which differentiates it from single-mechanism weight loss injections like semaglutide (Wegovy). Mounjaro received MHRA approval for weight management in UK adults, and it carries Black Triangle ▼ status — this means the MHRA is actively monitoring its safety profile and healthcare professionals must report adverse effects.
In the UK, you can access Mounjaro through two main routes: NHS specialist services (tier 3 weight management services, typically following GP referral) or private prescribing via UK-licensed prescribers following an online clinical assessment. Availability through the NHS varies significantly by region and waiting lists can be lengthy. Private access is faster but involves costs typically ranging from £150–£320 per month depending on dose. Your GP can advise on NHS eligibility and referral pathways.
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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.
Mounjaro Dose Titration, Side Effects, and What to Expect
Mounjaro uses a step-up dosing schedule starting at 2.5 mg weekly, with doses increasing every 4 weeks to a maximum of 15 mg. This dose titration helps minimise side effects common in the first weeks, including nausea, diarrhoea, and constipation. Most side effects settle as your body adjusts. In clinical trials (SURMOUNT-1), participants lost an average of 15–21% body weight on Mounjaro at 15 mg — though individual results vary significantly. Clinical trials showed results achieved alongside reduced-calorie diet and increased physical activity. Calculate your potential weight loss using our GLP-1 weight loss calculator and assess your BMI using our free BMI calculator to understand your starting point and health context.
- 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 the UK?
Mounjaro is approved for NHS prescribing through specialist tier 3 weight management services. However, availability varies by region and waiting lists can be very long. You'll need a GP referral to specialist services and must meet eligibility criteria: BMI ≥30, or BMI 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease.
Who manufactures Mounjaro and is it safe?
Mounjaro is made by Eli Lilly and Company. It's licensed by the MHRA with Black Triangle ▼ status, meaning it undergoes additional safety monitoring. The MHRA only approves medicines they consider safe and effective. Always discuss any concerns with your prescriber or GP.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is made by Eli Lilly and is a dual GIP + GLP-1 agonist. Wegovy (semaglutide) is made by Novo Nordisk and is a GLP-1-only agonist. Both are once-weekly injections. Clinical trials showed Mounjaro may produce slightly larger average weight loss (15–21% vs 15%), though individual results vary. Both require prescriptions and clinical assessment.
How much does Mounjaro cost privately in the UK?
Private Mounjaro costs typically range from £150–£320 per month depending on the dose and provider. Costs increase as you move to higher doses (2.5 mg to 15 mg). NHS access is free but requires specialist referral and may involve waiting lists. Online prescribers can provide estimates during consultation.
What happens if I can't get Mounjaro on the NHS?
If NHS waiting lists are lengthy or you don't meet tier 3 referral criteria, private prescribing is available through UK-licensed prescribers via online consultation. A prescriber will assess your eligibility, BMI, health history, and any contraindications before issuing a prescription. A GPhC-registered pharmacy then dispenses it.
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.