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 Comparison in the UK: NHS vs Private Access
If you're considering Mounjaro for weight management in the UK, understanding how to access it through the NHS versus private routes is essential. Mounjaro (tirzepatide) is now available through both NHS specialist services and private online prescribing, but eligibility criteria and costs differ significantly. This guide explains the UK prescribing landscape, NICE guidance, and how Mounjaro compares to other weight loss options like Wegovy. Our free BMI calculator can help you understand your starting point and eligibility for treatment.
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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.
NHS Access and NICE Guidance for Mounjaro in the UK
NICE approval: The National Institute for Health and Care Excellence (NICE) approved tirzepatide (Mounjaro) for weight management in the NHS in 2024, recognising its dual GIP and GLP-1 mechanism as offering a novel approach compared to single GLP-1 agonists like Wegovy. However, NHS availability is limited to specialist tier 3 and tier 4 weight management services, not standard GP prescription.
NHS eligibility criteria: Adults may access Mounjaro through the NHS if they have a BMI of 30 kg/m² or above, or BMI of 27–29.9 kg/m² with weight-related health conditions (type 2 diabetes, hypertension, sleep apnoea, cardiovascular disease). For South Asian, Chinese, Black African, and Black Caribbean patients, lower thresholds apply (BMI 27.5 or above). Referral typically comes from your GP to a tier 3 service, though waiting lists in many regions are substantial—sometimes 6–18 months depending on your ICB (Integrated Care Board) area.
Expected outcomes: Clinical trial data (SURMOUNT-1) showed average weight loss of approximately 15–21% of body weight at the maximum 15 mg dose over 72 weeks, when combined with reduced-calorie diet and increased physical activity. Individual results vary significantly.
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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.
NHS vs Private Routes: Cost, Speed, and Eligibility
NHS route: Free at point of use once prescribed through a specialist service, but involves a GP referral, specialist assessment appointment, and potentially lengthy waiting lists. Once approved, treatment is funded by the NHS and you pay standard prescription charges only (or nothing if exempt).
Private route: Available immediately through GPhC-registered online pharmacies following a brief online clinical assessment with a UK-licensed prescriber. Costs range from approximately £129–£320 per month depending on dose (2.5 mg to 15 mg). Private treatment does not require NHS referral or specialist appointment attendance, making it faster but more expensive. Both routes require a valid prescription—Mounjaro is prescription-only in the UK and cannot be obtained without clinical assessment.
Mounjaro vs Wegovy (semaglutide): Both are once-weekly injections licensed for UK weight management. Mounjaro uses dual GIP+GLP-1 mechanism; Wegovy uses GLP-1 only. Trial data shows marginally higher weight loss with Mounjaro (15–21% vs ~15% with Wegovy), though individual response varies. Eligibility criteria are identical. Both are subject to supply constraints and regional variation on the NHS.
Use our free GLP-1 weight loss calculator to explore potential outcomes with different doses of Mounjaro, and our BMI calculator to check whether you may meet NHS or private eligibility criteria. Both tools provide a helpful starting point before speaking to your GP or a prescriber.
- 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.
Can I get Mounjaro on the NHS in the UK?
Yes—NICE approved tirzepatide (Mounjaro) for NHS use in 2024. However, it's only available through specialist tier 3 weight management services, not standard GP prescription. You need a referral from your GP and must meet eligibility criteria (BMI ≥30, or ≥27 with weight-related health conditions). Waiting times vary by region but are often several months to over a year.
How much does Mounjaro cost privately in the UK?
Private Mounjaro costs typically range from £129–£320 per month depending on the dose (2.5 mg to 15 mg). Costs vary by provider. You'll need an online clinical assessment and valid prescription from a UK-licensed prescriber. The GPhC-registered online pharmacies handle both prescription and dispensing.
Is Mounjaro better than Wegovy for weight loss?
Clinical trials showed Mounjaro may offer slightly higher average weight loss (15–21% vs ~15% for Wegovy) due to its dual GIP+GLP-1 mechanism, but individual results vary significantly. Both are once-weekly injections with similar eligibility. Choice depends on your prescriber's recommendation, personal tolerance, and availability.
What's the difference between NHS and private Mounjaro prescribing?
NHS Mounjaro is free once prescribed but involves waiting lists (often 6+ months) and referral through specialist services. Private Mounjaro is available immediately via online prescribing but costs £129–£320/month. Medication and dosing are identical; access route differs.
How long does it take to get Mounjaro from a private prescriber in the UK?
Typically 24–48 hours from initial online assessment to prescription and pharmacy dispatch. This is significantly faster than NHS routes, where referral, assessment appointments, and waiting lists can take 6–18 months depending on your region.
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.