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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What Is the Age Limit for Mounjaro in the UK?
Mounjaro (tirzepatide) is a prescription-only weight management injection licensed in the UK for adults aged 18 years and over. There is no upper age limit — older adults can be prescribed Mounjaro if they meet NHS eligibility criteria and have been assessed as clinically suitable. Age alone does not determine eligibility; your GP or prescriber will consider your overall health, any existing medical conditions, and whether weight loss medication is appropriate for you. This guide explains UK prescribing rules, NHS access routes, and what determines whether you're eligible regardless of your age group.
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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.
Age Eligibility and NHS Prescribing Rules for Mounjaro
Minimum age: Mounjaro is not licensed or recommended for anyone under 18 years old in the UK. If you are aged 18 or above, you may be eligible depending on your BMI and health status.
No maximum age: Unlike some medications, Mounjaro has no upper age limit. Older adults (65+, 75+, or older) can be prescribed tirzepatide if clinically appropriate. However, prescribers pay closer attention to existing health conditions, medications you're taking, and kidney function in older patients.
NHS tier 3 specialist services assess eligibility based on BMI (30 or above, or 27+ with weight-related conditions like type 2 diabetes or high blood pressure) rather than age. Your GP can refer you to specialist weight management services, though waiting times vary significantly across the UK. Use our free BMI calculator to check where you sit on the NHS scale, then discuss NHS options with your GP.
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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.
Age Considerations and NHS vs Private Routes
Older adults may face additional screening before being prescribed Mounjaro — prescribers typically check kidney function (eGFR), liver function, and review any existing medications. This is standard caution, not an age-based barrier. NHS access involves referral to tier 3 specialist weight management services, usually requiring a GP appointment first. Private prescribing through GPhC-registered online services also requires a clinical assessment covering your full health history, and age is considered alongside overall fitness for treatment. Our GLP-1 weight loss calculator can help you estimate projected outcomes, which you can then discuss with your prescriber regardless of your age.
If you're over 65 or have existing health conditions (heart disease, type 2 diabetes, high blood pressure), prescribers will want to understand whether Mounjaro is safe for you specifically. This is not about age discrimination — it's about ensuring the medication is right for your individual health profile. Whether you access Mounjaro through the NHS or privately, you'll need a clinical assessment confirming you're medically suitable. Age alone will not prevent you from accessing weight management treatment in the UK if you meet the clinical criteria.
- 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 there a maximum age limit for Mounjaro in the UK?
No. Mounjaro has no upper age limit in the UK. Adults aged 65, 75, 80, or older can be prescribed tirzepatide if they meet BMI eligibility criteria and a prescriber assesses them as clinically suitable. Age-related health checks (kidney function, medications review) are standard but do not automatically exclude older adults.
Can teenagers or young people under 18 get Mounjaro?
No. Mounjaro is not licensed for anyone under 18 in the UK. Young people with excess weight should be assessed through NHS tier 1 and tier 2 services, including lifestyle programmes and community-based support. Your GP can discuss age-appropriate options.
What health checks will I need before being prescribed Mounjaro as an older adult?
Prescribers typically check kidney function (eGFR), liver function, and review your current medications and existing health conditions. These checks ensure Mounjaro is safe for you personally. You may also be asked about your cardiovascular health and blood pressure. These are standard precautions, not age barriers.
Does the NHS age threshold for Mounjaro differ from private prescribing?
No. Both NHS and private prescribers follow the same MHRA-licensed age rule: 18 years and above only. Both routes require a clinical assessment. NHS access is through specialist tier 3 services (referral needed); private access is through online clinical assessments. Age eligibility is identical.
Can I get Mounjaro on the NHS if I'm over 70?
Yes, if you meet BMI criteria (30 or above, or 27+ with weight-related health conditions) and a specialist prescriber assesses you as suitable. NHS tier 3 weight management services do not have an upper age limit. However, NHS availability varies by region, and waiting times can be lengthy. Ask your GP about local options.
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.