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 More Expensive Than Wegovy?
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) are prescription-only weight loss injections licensed in the UK, but Mounjaro typically costs more. The price difference comes down to several factors: manufacturing costs, the dual mechanism of action, patent positioning, and market availability. Understanding why will help you have a more informed conversation with your prescriber about which option might be suitable for your circumstances.
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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 the Medications Differ in Mechanism and Cost
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist—it activates two separate hormone pathways simultaneously. Wegovy (semaglutide) is a single GLP-1 receptor agonist. This fundamental difference in mechanism influences pricing: dual-action medications typically involve more complex manufacturing processes and development costs, which are reflected in the final price.
In the UK, Mounjaro generally costs between £150–£300 per dose depending on the strength and provider, while Wegovy typically ranges from £129–£250. Both are available through NHS specialist weight management services (though NHS availability varies significantly by region) and through private online prescribing. The cost per dose increases with higher strengths, as both medications are titrated upwards over several weeks. A full treatment course with either medication can cost £500–£1,500+ per month privately, depending on the dose reached and the provider.
- Mounjaro requires dose titration from 2.5 mg up to a maximum of 15 mg weekly
- Wegovy requires dose titration from 0.25 mg up to a maximum of 2.4 mg weekly
- Mounjaro's higher starting point and wider dose range may contribute to different pricing structures
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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.
Clinical Evidence and Individual Suitability
In clinical trials, both medications demonstrated significant weight loss: SURMOUNT-1 (Mounjaro) showed average weight loss of approximately 15–21% of body weight at the highest dose, whilst STEP-1 (Wegovy) showed approximately clinically studied weight loss at 68 weeks. However, individual results vary considerably, and what works best depends on your personal health profile, medical history, and how you respond to treatment. Your prescriber will assess which option is most suitable for you following a clinical assessment—cost should not be the only factor in this decision.
Both medications are prescribed for adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions (such as type 2 diabetes, hypertension, or cardiovascular disease). Lower thresholds apply for adults of South Asian, Chinese, Black African, or Black Caribbean heritage. Try our free GLP-1 weight loss calculator to explore potential outcomes, and discuss pricing and suitability with your GP or a licensed prescriber before making a decision.
- 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 always more expensive than Wegovy in the UK?
Generally yes, but prices vary by provider and dose. Private costs for Mounjaro typically range £150–£300 per dose, whilst Wegovy ranges £129–£250. NHS availability and costs depend on your region and specialist service. Always request a price comparison from your provider before committing.
Why does Mounjaro have a different mechanism than Wegovy?
Mounjaro activates both GIP and GLP-1 hormone pathways (dual action), whilst Wegovy activates only GLP-1. This dual mechanism in tirzepatide may offer different effects on appetite and metabolism, but also requires different manufacturing processes, contributing to higher costs.
Can I switch from one medication to the other for cost reasons?
Any medication switch must be managed by your prescriber, not based on cost alone. Switching involves stopping one medication safely and starting another with a new titration schedule. Discuss cost concerns openly with your GP or prescriber—they may be able to help find a sustainable option.
Will the NHS prescribe Mounjaro or Wegovy for free?
NICE has approved both tirzepatide (Mounjaro) and semaglutide (Wegovy) for NHS weight management services, but availability varies significantly by region and local ICB funding. Waiting lists can be very long. Private prescribing is an alternative if NHS waiting times are prohibitive for you.
Which medication is "better" for weight loss?
Both are effective, but results vary individually. Mounjaro showed slightly higher average weight loss in trials (15–21% vs 14.9%), but differences are modest. The best choice depends on your eligibility, medical history, side effect tolerance, and cost. Your prescriber will help determine suitability.
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.