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
Free tracker included with every download this week
What's the Cheapest Mounjaro Price in the UK?
Mounjaro (tirzepatide) costs vary in the UK depending on whether you access it through the NHS or privately. Private prescriptions typically range from £129–£320 per month depending on your dose, while NHS access is free but involves waiting lists and regional variation. To help you understand your options, we'll compare Mounjaro pricing with Wegovy and explain how each medication works, so you can make an informed decision with your GP or prescriber.
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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.
Mounjaro vs Wegovy — Cost, Mechanism, and Trial Data
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, meaning it activates two natural hormone pathways that regulate appetite and blood sugar. The SURMOUNT-1 clinical trial showed participants lost an average of 15–21% of their body weight over 72 weeks, depending on dose. The KwikPen is supplied as a pre-filled injection device with four weeks' supply per box.
- Doses: Start at 2.5 mg, escalate weekly by 2.5 mg increments up to a maximum of 15 mg once weekly
- Private cost: Typically £129–£220/month at lower doses (2.5–7.5 mg), rising to £200–£320/month at maintenance doses (10–15 mg)
- NHS access: Free through specialist tier 3 weight management services; subject to regional availability and NICE approval
Wegovy (semaglutide) is a single GLP-1 receptor agonist with a slightly different mechanism. The STEP-1 clinical trial demonstrated an average weight loss of approximately 14.9% over 68 weeks. It comes as a pre-filled auto-injection pen.
- Doses: Start at 0.25 mg, escalate over 5 weeks to 2.4 mg once weekly (maximum dose)
- Private cost: Typically £129–£180/month at therapeutic doses
- NHS access: Also available through tier 3 specialist services where clinically appropriate
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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.
Which is Right for You — Prescriber Assessment and Suitability
Both medications require a prescription and clinical assessment — neither can be purchased without one. A licensed prescriber will evaluate your BMI, weight-related health conditions (such as type 2 diabetes, hypertension, or sleep apnoea), and medical history to determine which is suitable for you. Use our free GLP-1 weight loss calculator above to estimate potential weight loss at different doses; however, this is for educational purposes only and does not replace a clinical assessment.
Key factors in prescriber choice include: mechanism preference (single vs. dual pathway), your individual response to similar medications, any contraindications, and availability through your chosen provider. Individual results vary significantly — the trial averages do not predict personal outcomes. If cost is a factor, discuss generic alternatives or NHS referral pathways with your GP, as waiting lists and regional commissioning affect access.
- 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 cheaper than Wegovy in the UK?
Private pricing is similar — both typically cost £129–£220/month at standard therapeutic doses. Exact cost depends on your dose tier and provider. NHS access to both is free but subject to availability and waiting lists. Check current pricing with multiple GPhC-registered providers for the most accurate quote.
Can I get Mounjaro on the NHS in the UK?
Yes. Mounjaro is NICE-approved for use within NHS tier 3 specialist weight management services. Access requires referral from your GP and assessment by a specialist multidisciplinary team. Availability and waiting times vary significantly by region (Integrated Care Board). Some areas have multi-month waiting lists.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP+GLP-1 agonist; Wegovy (semaglutide) is a GLP-1 agonist only. Clinical trials showed Mounjaro produced slightly higher average weight loss (15–21% vs. 14.9%), but individual results vary. Both are once-weekly injections. A prescriber will advise which suits you based on your health profile.
What is a Mounjaro KwikPen and how does it work?
The KwikPen is a pre-filled injection device supplied by Eli Lilly. Each pen contains four weekly doses. You inject once weekly into your stomach, thigh, or upper arm. Storage: refrigerate unopened pens; after first use, keep at room temperature (below 30°C) for up to 30 days. Detailed instructions come with each prescription.
How do I know if I'm eligible for Mounjaro or Wegovy?
Both require a BMI of 30 or above, or 27–29.9 with weight-related health conditions (diabetes, hypertension, sleep apnoea, cardiovascular disease). South Asian, Chinese, Black African, and Black Caribbean adults may be eligible at lower thresholds. A prescriber or GP will assess your individual eligibility following a clinical consultation.
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.