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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Mounjaro Jabs — NHS Weight Management in the UK
Mounjaro jabs, containing the active ingredient tirzepatide, are prescription-only weekly weight loss injections now available through NHS specialist weight management services in the UK. As a GIP and GLP-1 receptor agonist, Mounjaro works by helping regulate appetite and blood sugar control. Access through the NHS involves referral to tier 3 specialist services, where eligibility is assessed based on BMI and weight-related health conditions. This guide explains NHS prescribing, NICE approval status, and how to access Mounjaro through both NHS and private routes in the UK.
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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 Eligibility and NICE Approval for Mounjaro
NICE approval: The National Institute for Health and Care Excellence (NICE) has approved tirzepatide (Mounjaro) for weight management within NHS specialist tier 3 weight management services. This represents formal recognition of the medication's clinical value within the NHS framework.
NHS eligibility criteria: You may be eligible for Mounjaro through the NHS if you have a BMI of 30 kg/m² or above, or a BMI of 27–29.9 kg/m² with weight-related health conditions such as type 2 diabetes, prediabetes, high blood pressure, abnormal blood fats, obstructive sleep apnoea, or cardiovascular disease history. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds may apply due to higher metabolic risk at lower weights.
Access route: NHS access requires GP referral to your local tier 3 weight management service. Availability varies significantly by region (integrated care board). Many areas have substantial waiting lists.
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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.
NHS vs Private Access for Mounjaro Jabs
NHS route: Free through the NHS once accessed, but requires GP referral and specialist assessment. Regional variation means access may take months or longer in some areas. Prescribed within NHS tier 3 services with ongoing GP support.
Private route: Available through GPhC-registered online prescribing services following a clinical assessment with a UK-licensed prescriber. Faster access (typically within days) but involves direct cost (approximately £120–£250 monthly depending on dose). Both routes require a valid prescription and clinical suitability assessment. Use our GLP-1 weight loss calculator to understand potential outcomes, and our BMI calculator to check your starting point.
NHS route: Free through the NHS once accessed, but requires GP referral and specialist assessment. Regional variation means access may take months or longer in some areas. Prescribed within NHS tier 3 services with ongoing GP support.
Private route: Available through GPhC-registered online prescribing services following clinical assessment with a UK-licensed prescriber. Faster access (typically within days) but involves direct cost (approximately £120–£250 monthly depending on dose). Both routes require a valid prescription and clinical suitability assessment. Use our GLP-1 weight loss calculator to understand potential outcomes, and our BMI calculator to check your starting point.
- 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?
Yes, Mounjaro (tirzepatide) has been approved by NICE for use within NHS specialist tier 3 weight management services. However, access requires GP referral and availability varies by region. Many areas have significant waiting lists. Your GP can discuss referral options and regional availability.
What is the difference between Mounjaro and Ozempic?
Mounjaro is a dual GIP and GLP-1 receptor agonist, whilst Ozempic contains semaglutide and is approved for type 2 diabetes management. Mounjaro is licensed specifically for weight management in the UK, whereas Ozempic is not licensed for weight loss.
How much weight can I expect to lose on Mounjaro NHS treatment?
Clinical trials showed an average weight loss of 15–21% of body weight on Mounjaro, though individual results vary significantly. Weight loss depends on adherence to medication, dietary changes, physical activity, and personal metabolism. Your healthcare team can discuss realistic expectations.
How is Mounjaro dosed through the NHS?
Mounjaro starts at 2.5 mg weekly, increasing every 4 weeks to a maximum of 15 mg weekly. Your specialist team will manage dosing based on your response and tolerability. The KwikPen contains 4 weekly doses.
What are the common side effects of Mounjaro jabs?
Very common side effects include nausea, diarrhoea, vomiting, and stomach pain, particularly when starting or increasing doses. These often improve over time. Serious side effects are rare but include severe stomach pain (possible pancreatitis) and gallbladder problems — seek urgent medical attention if these occur.
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.