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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How Much Does Mounjaro Cost Per Month in the UK?
Mounjaro (tirzepatide) costs vary significantly depending on whether you access it through the NHS or privately in the UK. Private monthly costs typically range from £129 to £320, depending on your dose, with the maximum dose (15mg) being the most expensive. NHS access is free at point of use but involves longer waiting times and regional variation. Understanding both routes and how Mounjaro compares to alternative weight loss injections like Wegovy can help you make an informed decision about which option suits your circumstances.
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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.
Mounjaro vs Wegovy — Cost and Mechanism Comparison
Both Mounjaro and Wegovy are prescription-only weight loss injections available in the UK, but they work differently and have different pricing structures. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. Private costs for Mounjaro typically range from £129–£320 monthly depending on dose, whereas Wegovy private costs are usually £150–£350 monthly. Clinical trial data shows Mounjaro achieved average weight loss of 15–21% of body weight (SURMOUNT trial), while Wegovy achieved approximately 15% (STEP-1 trial) — though individual results vary significantly. Both require a KwikPen prescription weight loss injection and are administered once weekly. The choice between them depends on personal suitability, which your prescriber will assess during a clinical consultation.
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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 — Costs and Timelines
In the UK, NHS access to Mounjaro is free at point of use but is limited to tier 3 specialist weight management services. NICE (National Institute for Health and Care Excellence) has approved tirzepatide for NHS use, but availability varies significantly by region and ICB (Integrated Care Board). Waiting lists can extend from months to years in many areas. Private prescribing offers faster access without NHS referral — costs typically include the injection (£129–£320 per month depending on dose) plus a consultation fee (£20–£50). Your prescriber will assess whether you're eligible based on your BMI and weight-related health conditions. Use our free GLP-1 weight loss calculator to explore potential outcomes, and our BMI calculator to determine your starting point before consulting 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.
What's the difference between Mounjaro's mechanism and Wegovy's?
Mounjaro is a dual GIP and GLP-1 receptor agonist, meaning it activates two hormone pathways. Wegovy is a GLP-1 agonist only, activating one pathway. The dual mechanism may explain Mounjaro's slightly higher average weight loss in clinical trials (15–21% vs 15%), though results vary by individual and prescriber assessment determines which suits you best.
Can I get Mounjaro free on the NHS in the UK?
Yes, Mounjaro is approved by NICE for NHS use within specialist tier 3 weight management services. Access is free at point of use, but availability varies by region and waiting times can be lengthy. Your GP can refer you to your local specialist service. Private access is faster but requires payment.
What does a Mounjaro KwikPen cost privately per month?
Private Mounjaro costs range from approximately £129–£320 per month depending on your dose. The starting dose (2.5mg) is cheaper; the maximum dose (15mg) is most expensive. Costs vary slightly between providers. Many private consultations also include a separate prescriber fee of £20–£50.
How do Mounjaro and Wegovy dosing schedules differ?
Both are once-weekly injections using pre-filled pens. Mounjaro starts at 2.5mg and escalates up to 15mg maximum over weeks. Wegovy starts at 0.25mg and escalates to 2.4mg maximum. Dose titration timelines differ, so your prescriber will advise the schedule suited to you based on clinical assessment.
Is prescription weight loss injection UK coverage the same across all regions?
No. NHS access to tirzepatide (Mounjaro) and semaglutide (Wegovy) varies by ICB and local specialist service availability. Some regions have better access than others, with waiting times ranging from months to years. Private prescribing is consistent nationwide — you access it through online consultation with any UK-licensed prescriber.
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.