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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Why Is Mounjaro Price Increasing — And How Does Wegovy Compare?
Mounjaro (tirzepatide) prices have risen significantly across UK private prescribers since its approval for weight management. This price increase reflects supply constraints, manufacturing costs, and increasing demand. If you're exploring weight loss options, understanding the cost difference between Mounjaro and Wegovy — and what drives these prices — can help you make an informed decision about which prescription medication might suit your needs and budget. Both are prescription-only medicines requiring clinical assessment before use.
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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 Pricing and Wegovy Cost Comparison
Mounjaro (tirzepatide) pricing in the UK has increased from around £149–£180 per month in early 2024 to £250–£320+ in 2025, depending on dose and provider. The price rise is driven by several factors: increasing global demand for GLP-1 and dual GIP/GLP-1 medications, supply chain pressures, manufacturing scale-up by Eli Lilly, and fluctuating raw material costs. Additionally, tirzepatide is a newer, more complex molecule than semaglutide, which can affect production costs.
Wegovy (semaglutide) pricing has remained relatively stable at around £129–£180 per month across most UK private prescribers. Semaglutide has been available longer, allowing better supply chain optimisation and more competitive pricing from multiple generic manufacturers in some markets.
- Mounjaro: typically £250–£320/month (depending on dose)
- Wegovy: typically £129–£180/month
- NHS access: available through specialist tier 3 weight management services (no cost to patient, but availability varies by region)
Both medications require a prescription and clinical assessment. Your prescriber will determine which — if either — is suitable based on your individual health profile, eligibility, and preferences.
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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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Mounjaro vs Wegovy — Mechanism, Efficacy, and Individual Suitability
Mounjaro works as a dual GIP/GLP-1 receptor agonist, activating two natural hormone pathways simultaneously. Clinical trials (SURMOUNT-1) showed average weight loss of 15–21% of body weight at maximum dose. Wegovy is a GLP-1-only receptor agonist, and trials (STEP-1) showed average weight loss of approximately 15% of body weight.
Both medications are prescription-only, both require dose escalation over weeks, and both work alongside reduced-calorie diet and increased physical activity — not instead of lifestyle changes. Individual results vary significantly. The choice between them depends on your prescriber's clinical assessment, your medical history, eligibility criteria, and personal preference. Some patients respond better to one mechanism than the other, which is why NHS GPs and specialist prescribers evaluate each case individually. Use our free BMI calculator to check your personal health status, and discuss medication options with your prescriber if appropriate.
- 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.
Why has Mounjaro become more expensive than Wegovy in the UK?
Mounjaro prices have risen due to high global demand, supply constraints, manufacturing costs for the newer tirzepatide molecule, and Eli Lilly scaling production. Wegovy pricing has stabilised as semaglutide (the active ingredient) has been available longer with more established supply chains and greater manufacturing competition.
Is Mounjaro more effective than Wegovy?
Clinical trials show Mounjaro may result in slightly higher average weight loss (15–21% vs ~15%), but results vary between individuals. Effectiveness depends on personal response, adherence, and lifestyle factors. Your prescriber will assess which is more suitable for your individual health profile rather than assuming one is universally "better".
Can I access Mounjaro or Wegovy free through the NHS?
Yes. Both tirzepatide (Mounjaro) and semaglutide (Wegovy) are available through NHS specialist tier 3 weight management services. Access requires GP referral and can involve waiting lists. Availability varies significantly by region — check with your local Integrated Care Board (ICB).
What's the difference between GLP-1 and GIP/GLP-1 mechanisms?
GLP-1 (Wegovy) activates one hormone pathway to reduce appetite and support fullness. GIP/GLP-1 (Mounjaro) activates two pathways simultaneously, which some patients find more effective. Both mechanisms have strong clinical evidence, and suitability is individual.
Which medication should I choose — Mounjaro or Wegovy?
This is a clinical decision made between you and your prescriber after assessment. Factors include your eligibility, medical history, previous response to similar treatments, cost, and personal preference. Neither is universally "better" — prescriber guidance is essential.
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.