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 Voucher Codes and Wegovy — What You Need to Know
If you're looking for Mounjaro voucher codes or comparing costs between Mounjaro and Wegovy in the UK, it's important to understand how these prescription weight loss injections differ — not just in price, but in mechanism, dosing, and clinical evidence. Both medications are licensed for weight management in UK adults, but they work slightly differently. This guide explains the key differences to help you and your prescriber decide which may be more suitable for your individual 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 Mounjaro and Wegovy Work — Mechanism and Trial Data
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, meaning it activates two natural hormone pathways simultaneously. In the SURMOUNT-1 clinical trial, participants on Mounjaro 15 mg lost an average of approximately 20.9% of their body weight over 72 weeks, alongside a reduced-calorie diet and increased physical activity.
Wegovy (semaglutide) is a single GLP-1 receptor agonist, activating just the GLP-1 pathway. In the STEP-1 clinical trial, participants on Wegovy 2.4 mg (the maximum dose) lost an average of approximately 14.9% of body weight over 68 weeks, also with lifestyle support.
- Mounjaro: starting dose 2.5 mg, maximum 15 mg once weekly
- Wegovy: starting dose 0.25 mg, maximum 2.4 mg once weekly
- Both are prescription-only and require a clinical assessment before dispensing
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.
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Pricing, Vouchers, and Practical Differences in the UK
Mounjaro and Wegovy are available through NHS specialist weight management services (where waiting lists and regional availability vary considerably) and through private prescribers online. Private costs typically range from £129–£320 per month depending on dose and provider. Some private providers occasionally offer promotional codes or discounts — these vary and change regularly, so always check directly with the prescriber or pharmacy.
Both medications require prescription from a UK-licensed healthcare professional following a clinical assessment. Your prescriber will consider your BMI, any weight-related health conditions, medical history, and current medications when deciding which is appropriate. Neither is assured to work for everyone.
Use our GLP-1 weight loss calculator to estimate potential outcomes at different doses, and our BMI calculator to check your starting point.
Both Mounjaro and Wegovy slow gastric emptying and reduce appetite, but Mounjaro's dual mechanism may offer different satiety benefits for some people. However, this does not mean one is universally "better" — suitability depends on individual factors including metabolism, comorbidities, previous medication response, and personal preference. Your prescriber will discuss which is clinically appropriate for you.
If you're already on one medication and it's not working well, a switch to the other is possible — but this must always be managed by your prescriber, not attempted independently. Always allow sufficient time on a stable dose (minimum 4 weeks per dose level) before assessing effectiveness.
- 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.
Are Mounjaro voucher codes widely available in the UK?
Mounjaro voucher codes or promotional discounts vary by provider and change frequently. They are not centrally advertised by the manufacturer. Private prescribers and pharmacies occasionally offer promotional codes — check directly with your chosen provider. NHS access does not involve vouchers; prescriptions are issued through specialist weight management services.
Which is cheaper — Mounjaro or Wegovy?
Private pricing is similar, typically £129–£320 monthly depending on dose. Exact costs vary by provider. NHS access is free but limited by regional availability and waiting lists. Compare prices directly with your chosen prescriber or pharmacy, as costs change regularly.
Why did Mounjaro show better weight loss in trials than Wegovy?
The dual GIP+GLP-1 mechanism in Mounjaro may contribute to greater average weight loss in clinical trials. However, trial conditions (calorie deficit, exercise) differ between studies. Individual results vary significantly — some people respond better to Wegovy, others to Mounjaro. Your prescriber will advise based on your circumstances.
Can I switch from Wegovy to Mounjaro or vice versa?
Yes, switching is possible and may be appropriate if the first medication isn't working well. Any switch must be managed by your prescriber — never change medications independently. Expect at least 4 weeks at each new dose before reassessing effectiveness.
Do I need a voucher code to get Mounjaro or Wegovy in the UK?
No. To access either medication, you need a prescription from a UK-licensed prescriber following a clinical assessment. Private prescribers issue prescriptions directly to GPhC-registered pharmacies. Voucher codes are optional promotional discounts some providers offer — they're not required for access.
Ready to take control of your weight loss journey?
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