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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Has Mounjaro Gone Up In Price — Mounjaro vs Wegovy Comparison
Mounjaro (tirzepatide) pricing in the UK has fluctuated since launch, with costs varying between private prescribers and NHS access routes. Many people wonder whether Mounjaro or Wegovy (semaglutide) offers better value and effectiveness. Both are prescription-only weight management injections available in the UK, but they work differently, have different clinical trial results, and may suit different individuals. Understanding the key differences — mechanism, dosing, cost, and eligibility — helps you make an informed decision with your prescriber. Neither medication is available without a clinical assessment.
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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.
Mechanism Differences & Clinical Trial Evidence
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, activating two hormone pathways. Wegovy (semaglutide) is a GLP-1-only agonist — a single mechanism. In the SURMOUNT-1 clinical trial, Mounjaro 15 mg showed average weight loss of approximately 20.9% of body weight over 72 weeks. In the STEP-1 trial, Wegovy 2.4 mg showed average weight loss of approximately 14.9% over 68 weeks. However, individual results vary significantly.
- Mounjaro dosing: 2.5 mg to 15 mg once weekly (6 escalation steps)
- Wegovy dosing: 0.25 mg to 2.4 mg once weekly (5 escalation steps)
- Both require a reduced-calorie diet and increased physical activity for best results
- Both are administered via once-weekly injection pen
Try our GLP-1 weight loss calculator above to see projected outcomes at different doses for either medication.
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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.
UK Pricing, Eligibility & How to Access
Private Mounjaro pricing typically ranges from £129–£320 per month depending on dose, while Wegovy pricing is similarly variable. NHS access is through specialist tier 3 weight management services following referral from your GP — availability and waiting times vary significantly by region. Both medications require clinical assessment confirming BMI ≥30, or BMI 27–29.9 with weight-related conditions such as type 2 diabetes or cardiovascular disease.
- Private prescribing is faster but involves upfront costs
- NHS access is free but may involve waiting lists of months in many areas
- A licensed prescriber must assess individual suitability — neither is available without clinical approval
- Ethnicity-adjusted thresholds may apply for South Asian, Chinese, Black African, or Caribbean heritage adults
- 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 more expensive than Wegovy in the UK?
Pricing varies between prescribers for both medications. Private costs typically range £129–£320/month for either drug depending on dose. NHS access is free but involves referral to specialist services. Always check current pricing with your prescriber, as costs fluctuate.
Which medication causes more weight loss — Mounjaro or Wegovy?
Clinical trials showed Mounjaro averaged clinically studied weight loss at maximum dose, while Wegovy averaged 14.9%. However, results vary significantly between individuals. Your prescriber will assess which suits your health profile and goals best.
Can I switch from Wegovy to Mounjaro on the NHS?
NHS switching between medications depends on your local specialist service policy and clinical suitability. Your tier 3 weight management team will assess whether a change is appropriate. Private prescribers can also manage switches following clinical review.
What's the difference between Mounjaro and Wegovy mechanisms?
Mounjaro is a dual GIP + GLP-1 agonist (two hormone pathways), while Wegovy is GLP-1-only (single pathway). The dual mechanism may explain Mounjaro's slightly higher average weight loss in trials, but individual response varies considerably.
How do I check my BMI eligibility for either medication?
Use our free BMI calculator above to check your current BMI. Both medications require BMI ≥30 or BMI 27–29.9 with weight-related health conditions. Your GP or prescriber will confirm full eligibility after clinical assessment.
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.