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 vs Wegovy: Cost Comparison for UK Adults
If you're considering weight loss injections in the UK, cost is a key factor alongside effectiveness. Both Mounjaro (tirzepatide) and Wegovy (semaglutide) are prescription-only medications available through NHS specialist services or private prescribing. This guide compares their actual costs, dose ranges, and what affects the price you'll pay. Individual costs vary depending on where you access treatment and which dose you need.
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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.
Cost Comparison: NHS vs Private Pricing
Mounjaro (tirzepatide) private costs: Typically £129–£320 per month depending on dose. Starting at 2.5 mg (£129–£150), with maximum dose 15 mg (£280–£320). Each KwikPen contains 4 weeks of doses.
Wegovy (semaglutide) private costs: Usually £150–£290 per month depending on dose. Starting dose 0.25 mg, reaching maximum 2.4 mg. Requires dose titration over approximately 16–20 weeks.
NHS access: If prescribed through NHS tier 3 specialist weight management services, both medications are significantly cheaper or free at point of use, though NHS availability varies widely by region and waiting lists can be lengthy.
What affects pricing: Your current dose level (both require dose escalation), the provider or pharmacy you use, and whether you access NHS or private prescribing all influence final cost.
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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.
How Dose Titration Affects Overall Cost
Neither medication reaches maximum dose immediately. Mounjaro starts at 2.5 mg and escalates weekly over approximately 20 weeks. Wegovy escalates more gradually over 16–20 weeks from 0.25 mg. This means your early costs are lower, but increase as you progress through dose levels.
If you discontinue early, you'll spend less overall. However, weight regain often occurs after stopping—clinical data shows sustained treatment provides better outcomes. Budget for long-term use if considering private access. Our GLP-1 weight loss calculator can help project potential costs and outcomes across different dose levels.
- 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.
Which is cheaper: Mounjaro or Wegovy in the UK?
Privately, costs are similar (£129–£320/month for Mounjaro, £150–£290/month for Wegovy). Final price depends on your current dose and pharmacy. NHS costs are much lower if available in your area, but access varies significantly by region.
Do you need to stay on the maximum dose to see weight loss?
No. Clinical trials show meaningful weight loss at various doses. Mounjaro showed approximately 15% loss at 5 mg and 20.9% at 15 mg. Wegovy showed around 15% at 2.4 mg. Your prescriber will recommend an appropriate dose based on your response and tolerability.
Can you get Mounjaro or Wegovy free on the NHS?
Both are available through NHS tier 3 specialist weight management services, making them free at point of use. However, access varies by region (ICB), and waiting lists can be very long. Private access is available without NHS referral but costs apply.
Is one medication significantly more effective than the other for weight loss?
Mounjaro (dual GIP+GLP-1 mechanism) showed slightly higher average weight loss in SURMOUNT trials (~21% at 15 mg) compared to Wegovy's STEP trials (~15% at 2.4 mg). However, individual results vary significantly. Suitability depends on personal health factors—your prescriber will assess which is appropriate for you.
What happens to costs if you skip doses or stop treatment early?
Stopping early reduces total spending but increases risk of weight regain. Most people who discontinue regain weight over time. If considering private access, budget for sustained use. Our progress tracker can help you monitor results and discuss ongoing treatment with your prescriber.
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.