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 Prices Going Up — Wegovy Comparison Guide
Mounjaro prices have been rising across UK private prescribing services, prompting many people to compare tirzepatide with alternative weight management options like Wegovy. Both are prescription-only GLP-1 (or dual GIP+GLP-1) receptor agonist injections approved by the MHRA for weight management in UK adults. Understanding the clinical differences, trial data, and cost implications can help you make an informed decision alongside your prescriber. This guide compares the two medications factually so you can understand what each offers.
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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.
Clinical Trial Data — SURMOUNT vs STEP
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist studied in the SURMOUNT-1 clinical trial. At the maximum dose of 15 mg weekly, participants achieved an average weight loss of approximately 20.9% of their body weight over 72 weeks, alongside a reduced-calorie diet and increased physical activity. At the lower maintenance dose of 10 mg weekly, average weight loss was approximately 19.5%.
Wegovy (semaglutide) is a GLP-1-only receptor agonist studied in the STEP-1 clinical trial. At the maximum dose of 2.4 mg weekly, participants achieved an average weight loss of approximately 14.9% of their body weight over 68 weeks under similar lifestyle conditions.
- Mounjaro's dual mechanism may offer slightly greater average weight loss in trials
- Individual results vary significantly — some people respond better to one medication than the other
- Both require ongoing lifestyle changes (diet and physical activity) for sustained results
- Clinical trial outcomes are averages — your personal outcome cannot be predicted
Clinically BackedWeight Loss
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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.
Mechanism, Dose, and Suitability — A Practical Comparison
Mounjaro activates two hormone pathways (GIP and GLP-1), whilst Wegovy activates only the GLP-1 pathway. This dual action in Mounjaro may explain the slightly higher average weight loss in trials, though both medications slow stomach emptying and reduce appetite signalling. Mounjaro uses a KwikPen with doses ranging from 2.5 mg to 15 mg weekly, whilst Wegovy uses doses from 0.25 mg to 2.4 mg weekly. Neither medication is superior for every person — your prescriber will assess which is more suitable based on your health history, previous medication responses, and individual circumstances.
Rising Mounjaro prices may make Wegovy appear more cost-effective, but this should never be your only consideration. A licensed prescriber must evaluate both options for you. Use our free BMI calculator to understand your starting point, and discuss both tirzepatide and semaglutide options with your GP or prescriber if you're exploring weight management treatment.
- 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 are Mounjaro prices going up in the UK?
Mounjaro prices reflect supply, demand, and operational costs for private prescribing services. As Mounjaro has become more widely prescribed, some providers have adjusted pricing. This is separate from NHS pricing — NHS specialists prescribe Mounjaro within set service budgets. Private pricing is determined by each GPhC-registered pharmacy independently.
Is Wegovy cheaper than Mounjaro in the UK right now?
Pricing varies between providers and doses. Generally, at comparable dose levels, Wegovy can be more affordable than Mounjaro, but this is not assured. Compare costs across GPhC-registered pharmacies for current pricing on both medications. Your choice should be based on clinical suitability first, cost second.
Can I switch from Mounjaro to Wegovy if prices keep rising?
Switching between medications is a clinical decision, not a cost-driven one. If you're considering switching due to price, speak to your prescriber about your options. An approximate dose conversion exists (Mounjaro 10 mg ≈ Wegovy 1.7 mg), but any switch requires clinical assessment and guidance.
Do the SURMOUNT and STEP trials prove Mounjaro is better than Wegovy?
The trials show different average weight loss outcomes, but they're not directly comparable — different participant groups, timelines, and doses. Both medications are effective. Clinical trial averages don't predict individual outcomes. Your prescriber will help determine which suits you better based on your health profile.
How do I access Mounjaro or Wegovy in the UK if I'm concerned about cost?
NHS access is through specialist weight management services (tier 3/4) — free but often with waiting lists. Private prescribing is available through online consultations with UK-licensed prescribers, with costs varying by dose and provider. Speak to your GP about NHS options first, then explore private services if needed. Try our GLP-1 weight loss calculator to understand potential outcomes at different doses.
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.