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 2.5mg Price and How It Compares to Wegovy
The 2.5mg Mounjaro dose is the starting dose of tirzepatide, typically used for the first 4 weeks of treatment. While pricing varies depending on whether you access treatment through the NHS or a private prescriber, understanding how Mounjaro compares to Wegovy (semaglutide) can help you understand what your GP or licensed prescriber might recommend. Both are prescription-only weight management injections licensed in the UK, but they work differently and have different costs. This guide explains the pricing, mechanism differences, and how to access either medication.
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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.
Mounjaro 2.5mg vs Wegovy: Mechanism, Trial Data, and Cost
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, meaning it activates two hormone pathways in your body. Clinical trials (SURMOUNT-1) showed participants on Mounjaro lost an average of 15–21% body weight over 72 weeks, depending on dose. The 2.5mg dose is a starting dose only — most patients escalate to 5mg, 10mg, or higher over weeks and months.
Wegovy (semaglutide) is a GLP-1 receptor agonist only — it activates one pathway. STEP-1 trial data showed Wegovy users lost approximately 15% body weight on average at the maximum 2.4mg dose. Wegovy's starting dose is 0.25mg, significantly lower than Mounjaro's 2.5mg start.
Cost context: Private pricing ranges from approximately £129–£320 per month depending on dose and provider. NHS access is through specialist tier 3 services where available, though waiting lists vary by region. Individual results and suitability vary — your prescriber will assess which medication is appropriate for you based on clinical factors, not price alone.
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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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How Prescribers Decide: Individual Suitability Matters More Than Price
Both Mounjaro and Wegovy require a prescription and clinical assessment before use. A UK-licensed prescriber will evaluate your BMI, health conditions, medications, and personal circumstances to determine which medication (if either) is suitable for you. Neither medication is assured to work — weight loss varies significantly between individuals, even at the same dose.
If you're eligible for NHS specialist weight management services, a prescriber may offer either medication based on local availability and clinical guidelines. If accessing privately, cost may be one factor, but clinical suitability is always the primary consideration. Our GLP-1 weight loss calculator can help you estimate potential outcomes, but your prescriber's assessment is what matters for your actual treatment plan.
- 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 2.5mg cheaper than Wegovy?
Pricing varies by provider and dose. Both typically cost £129–£320/month privately, depending on whether you're on a starting dose (Mounjaro 2.5mg) or higher dose. Wegovy's maximum is 2.4mg, whilst Mounjaro goes up to 15mg. NHS costs nothing at the point of use if prescribed through specialist services, though NHS availability is limited.
Why does Mounjaro start at 2.5mg but Wegovy starts at 0.25mg?
Mounjaro and Wegovy have different mechanisms — Mounjaro is dual GIP+GLP-1, Wegovy is GLP-1 only. Mounjaro's higher starting dose reflects its dual action. Both escalate gradually over weeks to find an effective dose. Your prescriber will manage this escalation based on how you respond and tolerate the medication.
Do I need a prescription for Mounjaro 2.5mg in the UK?
Yes, Mounjaro is prescription-only. You'll need an assessment from a UK-licensed prescriber (GP, NHS specialist service, or private telemedicine provider) to confirm you meet eligibility criteria before a prescription can be issued. Prescription requirements are the same regardless of cost or dose.
Which lost more weight in clinical trials — Mounjaro or Wegovy?
SURMOUNT trial data showed Mounjaro users lost 15–21% body weight (depending on final dose), whilst STEP trial data showed Wegovy users lost approximately 15% at maximum dose. However, these are averages — individual results vary greatly. Your own weight loss depends on many factors beyond medication alone.
Can I switch from Wegovy to Mounjaro or vice versa?
Switching between medications must be managed by your prescriber. There is no official conversion chart between Mounjaro and Wegovy doses. If you're considering switching, discuss it with your GP or prescriber — they'll advise whether a switch is appropriate for you, when to stop one, and how to start the other safely.
Ready to take control of your weight loss journey?
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