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 5mg vs Wegovy: Finding the Cheapest Option
If you're looking for the cheapest Mounjaro 5mg option in the UK, you're likely weighing this against Wegovy, another popular GLP-1 weight management injection. Both are prescription-only medicines approved by the MHRA for adults with obesity or overweight with health conditions. Cost varies based on dose, prescriber, and whether you access treatment through the NHS or privately. This guide compares the two medications factually — covering how they work, clinical trial results, and what affects pricing — so you can make an informed decision with your GP or prescriber.
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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 Differently
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist — meaning it activates two hormone pathways that regulate appetite and blood sugar. Wegovy (semaglutide) is a GLP-1 receptor agonist only, activating a single pathway. This difference in mechanism may affect how individuals respond. Mounjaro starts at 2.5mg and escalates to a maximum of 15mg weekly. Wegovy begins at 0.25mg and reaches a maximum of 2.4mg weekly — substantially lower absolute doses. Clinical trials (SURMOUNT-1 for Mounjaro, STEP trials for Wegovy) showed that Mounjaro achieved slightly higher average weight loss: approximately 20.9% at maximum dose versus 14.9% for Wegovy. However, individual results vary significantly. Both require a reduced-calorie diet and increased physical activity for optimal results. Use our free GLP-1 weight loss calculator to see projected outcomes at different doses, and the BMI calculator to check your starting point.
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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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Cost, Eligibility, and Access in the UK
Private prescription costs differ between providers and by dose. At 5mg, Mounjaro typically costs £150–£200 per month privately, while Wegovy at equivalent doses may range £129–£180. However, the 5mg Mounjaro dose is often an intermediate step during titration — many people increase beyond this, changing long-term costs. NHS access is through specialist tier 3 weight management services following GP referral and can have waiting lists of several months depending on your region. Both medications require a clinical assessment confirming you meet eligibility criteria: BMI ≥30, or BMI 27–29.9 with weight-related health conditions like hypertension or type 2 diabetes. Your prescriber will assess which medication suits your individual health profile, not just cost.
- 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 5mg cheaper than Wegovy per month?
Not necessarily. Private costs vary by provider and dose. Mounjaro 5mg typically costs £150–£200 monthly, while Wegovy may cost £129–£180 at comparable doses. However, 5mg Mounjaro is usually a temporary titration step, so long-term costs depend on your maintenance dose. Compare current prices from UK prescribers for the most accurate information.
Can I get Mounjaro or Wegovy free on the NHS?
Yes, both are available through NHS specialist weight management services (tier 3) following GP referral. Availability and waiting times vary significantly by region and ICB. Many areas have long waiting lists. Private access via online prescribers is faster but involves a cost.
Which medication causes more side effects — Mounjaro or Wegovy?
Both have similar common side effects: nausea, diarrhoea, vomiting, and stomach pain — particularly during dose escalation. Individual experiences vary greatly. Your GP or prescriber can discuss which might suit you better based on your medical history and tolerability.
What is the difference between Mounjaro and tirzepatide?
Mounjaro is the brand name for tirzepatide, a medication containing the active ingredient tirzepatide. They are the same medicine. Tirzepatide is the generic name; Mounjaro is how it's marketed and prescribed in the UK.
How do I know which medication to choose — cost or suitability?
Cost matters, but clinical suitability is more important. Your prescriber will assess your health profile, medical history, and individual factors to recommend which is appropriate. Never choose based on price alone. Discuss both options with your GP or specialist before deciding. ```
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