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 Price Increase 2025 and How It Compares to Wegovy
Mounjaro (tirzepatide) pricing in the UK has seen adjustments in 2025, prompting many people considering weight loss injections to compare costs with alternatives like Wegovy. Both are prescription-only GLP-1 and GLP-1-based medications available through UK prescribers, but they differ in mechanism, dosing schedules, and pricing structures. Understanding these differences—alongside trial data and individual suitability—helps you and your prescriber decide which option may be right for you.
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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.
Clinical Differences: Mechanism and Trial Evidence
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist—it activates two natural hormone pathways in the body, which may explain its stronger average weight loss results in clinical trials. The SURMOUNT-1 trial showed participants on the maximum 15mg dose lost an average of approximately 20.9% of their body weight over 72 weeks, alongside diet and exercise.
Wegovy (semaglutide) is a GLP-1-only receptor agonist, working through a single pathway. The STEP-1 trial demonstrated average weight loss of approximately 14.9% of body weight at the maximum 2.4mg dose over 68 weeks, also with lifestyle changes.
Both medications are injected once weekly. Mounjaro uses a KwikPen device with doses ranging from 2.5mg to 15mg. Wegovy starts at 0.25mg and titrates to a maximum of 2.4mg. Individual results vary significantly—trial averages do not predict personal outcomes.
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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.
Pricing, Prescribing Pathways, and Suitability
UK pricing for both medications varies by dose and provider. Private prescribers typically charge between £129–£320 per month depending on the dose prescribed. Both are prescription-only and require a clinical assessment—your prescriber will evaluate your BMI, health conditions, and contraindications to determine suitability.
NHS access is through specialist tier 3 weight management services following GP referral, with significant regional variation and waiting times. A prescriber will consider factors including your weight loss history, other medications, and individual health profile rather than price alone when deciding between them. Try our GLP-1 weight loss calculator to explore projected outcomes at different doses, and use the BMI calculator to check your current status.
- 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.
Has Mounjaro become more expensive in 2025?
Mounjaro pricing has adjusted in 2025 across UK private providers. Costs typically range from £129–£320 monthly depending on dose. NHS pricing differs as it's negotiated nationally. Individual prescriber pricing varies, so comparing quotes from multiple GPhC-registered pharmacies is recommended if sourcing privately.
Is Mounjaro more effective than Wegovy?
Clinical trials show Mounjaro achieved slightly higher average weight loss (20.9% vs 14.9%) in SURMOUNT and STEP trials respectively. However, individual results vary significantly. A prescriber will assess which is most suitable for you based on your health profile, not trial averages alone.
Which is cheaper—Mounjaro or Wegovy in the UK?
Private costs are similar, typically £129–£320 monthly for both medications depending on dose. Lower doses cost less than higher doses. NHS pricing is nationally negotiated. Compare quotes from multiple registered pharmacies for current pricing if paying privately.
What is the key difference between Mounjaro and Wegovy?
Mounjaro is a dual GIP+GLP-1 agonist (two hormone pathways), while Wegovy is a GLP-1-only agonist (single pathway). This dual mechanism may explain Mounjaro's slightly stronger trial results. Both are once-weekly injections requiring prescription and clinical assessment.
How do I decide between Mounjaro and Wegovy?
Your prescriber will assess your individual health, medical history, contraindications, and weight loss goals. Both require clinical assessment before prescription. Neither is "better"—suitability depends on your personal circumstances. Always discuss options with a 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.