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 vs Wegovy: Price and Prescription Comparison
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) are available as prescription-only weight management injections in the UK, but their pricing differs. Understanding the cost, how each medication works, and how to access them can help you and your GP make an informed decision. This guide compares both options factually, covering pricing structures, clinical effectiveness, and eligibility criteria to help you explore what's available.
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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.
How Mounjaro and Wegovy Compare: Mechanism, Dose, and Trial Results
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, meaning it activates two natural hormone pathways. Wegovy (semaglutide) is a GLP-1 receptor agonist only, activating one pathway. In the SURMOUNT-1 clinical trial, Mounjaro at maximum dose (15 mg weekly) showed average weight loss of approximately 20.9% body weight over 72 weeks. In the STEP-1 trial, Wegovy at maximum dose (2.4 mg weekly) showed average weight loss of approximately 14.9% body weight over 68 weeks. Both were used alongside a reduced-calorie diet and increased physical activity. Individual results vary significantly. Mounjaro starts at 2.5 mg weekly and increases gradually; Wegovy starts at 0.25 mg and escalates over 16 weeks. Both are once-weekly injections supplied as pre-filled pens.
- Mounjaro: Starts at 2.5 mg, maximum 15 mg per week
- Wegovy: Starts at 0.25 mg, maximum 2.4 mg per week
- Both: Once weekly, prescription-only, require clinical assessment
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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.
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UK Pricing, Access Routes, and Eligibility Considerations
Private prescription pricing varies by provider and dose. Mounjaro typically costs between £150–£300 per month depending on the dose, whilst Wegovy ranges from approximately £120–£290 per month. NHS access is through specialist tier 3/4 weight management services with referral from your GP; availability and waiting times vary significantly by region and NHS integrated care board (ICB). Both medications require a clinical assessment confirming you meet eligibility criteria: BMI 30 or above, or BMI 27–29.9 with weight-related health conditions such as type 2 diabetes, hypertension, or cardiovascular disease. Ethnicity-adjusted thresholds apply for South Asian, Chinese, Black African, and Black Caribbean adults (from BMI 27.5). Neither medication is suitable for pregnant individuals, those under 18, or people with certain medical conditions—your prescriber will assess individual suitability.
- 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 main difference between Mounjaro and Wegovy?
Mounjaro is a dual GIP and GLP-1 receptor agonist, activating two hormone pathways, whilst Wegovy is a GLP-1 agonist only. Clinical trials showed Mounjaro produced higher average weight loss (approximately 20.9% vs 14.9% body weight), though individual results vary. Both work alongside diet and exercise, and both require a prescription and clinical assessment.
How much do Mounjaro and Wegovy cost in the UK?
Private prescription costs vary by provider and dose. Mounjaro typically ranges from £150–£300 monthly; Wegovy from £120–£290 monthly. Exact pricing depends on the dose you're prescribed. NHS access is free but requires referral to a specialist weight management service, with significant regional variation and waiting times.
Can I get Mounjaro or Wegovy on the NHS?
Yes, both are available through NHS specialist tier 3/4 weight management services following a GP referral. However, availability and waiting lists vary significantly by region. Your local integrated care board (ICB) determines local access criteria and services. Your GP can advise on NHS options in your area.
Who is eligible for Mounjaro or Wegovy?
Both medications are for adults with a BMI of 30 or above, or BMI 27–29.9 with weight-related health conditions like type 2 diabetes, hypertension, or cardiovascular disease. For South Asian, Chinese, Black African, or Black Caribbean individuals, eligibility may start at a lower BMI (27.5 or above). A prescriber will assess your individual suitability.
Which medication will work better for me—Mounjaro or Wegovy?
This depends on your individual health, medical history, weight loss goals, and how your body responds. Clinical trials showed Mounjaro produced higher average weight loss, but individual outcomes vary considerably. Your GP or prescriber will assess which option is most appropriate for you based on your personal circumstances and medical history.
Ready to take control of your weight loss journey?
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