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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Wegovy vs Mounjaro — UK Cost and Access Compared
Wegovy (semaglutide) and Mounjaro (tirzepatide) are both prescription-only weight management injections available in the UK, but they differ significantly in cost, access routes, and how they're prescribed. This guide explains the real differences between accessing these medications through the NHS and privately, helping you understand your options and what to expect during the consultation process.
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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.
UK Cost Comparison: Wegovy vs Mounjaro Private Prescription
Both Wegovy and Mounjaro are available privately in the UK through licensed prescribers, but costs vary by provider and dose.
- Wegovy (semaglutide): Private prescriptions typically cost £129–£299 per month depending on dose (0.25 mg to 2.4 mg). Most people start at lower doses and increase gradually, so initial costs may be lower.
- Mounjaro (tirzepatide): Private prescriptions typically range from £139–£319 per month depending on dose (2.5 mg to 15 mg). Like Wegovy, starting doses are usually lower with gradual escalation.
- What's included: Most private providers include the prescription, clinical assessment, and ongoing follow-up consultations in their quoted price. The medication itself (the KwikPen or pen device) is dispensed by a GPhC-registered pharmacy.
- Variation by provider: Prices vary between online prescribing services, so it's worth comparing. Some offer discounts for upfront payment or longer-term plans.
Use our free GLP-1 weight loss calculator above to explore how different doses work and what you might expect over time.
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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.
NHS vs Private Access: Routes and Timelines
NHS Route: Both Wegovy and Mounjaro are approved by NICE for NHS use, but access is through specialist tier 3 and tier 4 weight management services, not standard GP prescription. You'll need a referral from your GP to a local specialist service. Availability and waiting times vary dramatically by region (ICB) — some areas have months-long waiting lists, others have very limited provision. NHS prescriptions are free once approved.
Private Route: Available without NHS referral through online consultations with UK-licensed prescribers. The process typically takes 24–48 hours from initial consultation to prescription. You'll complete a health questionnaire, have a video or telephone assessment, and if approved, receive a prescription to be dispensed by a participating pharmacy. This is faster but involves out-of-pocket costs.
- 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.
What's the main cost difference between Wegovy and Mounjaro in the UK?
Both typically cost £129–£319 per month privately, depending on dose. The difference is usually small — Mounjaro may be slightly higher at maximum doses. NHS access is free but involves potentially lengthy waiting times for specialist referral. Starting doses for both are cheaper than maintenance doses.
Can I get Mounjaro or Wegovy on the NHS in 2024?
Yes, both are NICE-approved for NHS use through specialist weight management services. However, you need a GP referral to your local tier 3 service, and availability varies significantly by region. Many areas have substantial waiting lists. Your GP can advise you on your local NHS provision and whether you meet eligibility criteria for specialist referral.
How long does a private online consultation take?
The initial consultation typically takes 15–30 minutes via video or telephone. You'll be asked about your medical history, current medications, weight, and health goals. If approved, you'll receive a prescription within 24–48 hours. Follow-up consultations are usually shorter and can often be done via app or email check-ins.
Do I need to meet specific BMI criteria to get Wegovy or Mounjaro privately?
Private prescribers use similar criteria to the NHS: BMI of 30 or above, or BMI 27–29.9 with a weight-related health condition (diabetes, hypertension, heart disease, etc.). However, private prescribers may have slightly different assessment criteria. You'll be assessed individually during your consultation, and a prescriber will decide if treatment is appropriate for you.
Can I switch between Wegovy and Mounjaro if one doesn't suit me?
Yes, you can switch, but it must be done under prescriber guidance — never stop one and start another without medical oversight. If you're accessing privately, inform your prescriber that you want to switch. If on the NHS, your specialist service can manage the transition. Switching typically involves stopping one medication and starting the other after an appropriate interval.
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.