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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Buying Mounjaro Privately — How It Compares to Wegovy
If you're considering buying Mounjaro privately in the UK, you may be wondering how it compares to Wegovy, the other major GLP-1 weight management injection available. Both are prescription-only medicines that require a clinical assessment before dispensing, but they work differently and have different dosing schedules. This guide explains the key differences to help you understand what a prescriber might consider when assessing your suitability for 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.
Mechanism and Trial Data — Mounjaro vs Wegovy
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, meaning it activates two hormone pathways rather than one. This dual mechanism may explain why clinical trials showed slightly higher average weight loss: participants in the SURMOUNT-1 trial lost an average of 20.9% body weight on the maximum 15 mg dose over 72 weeks.
Wegovy (semaglutide) is a GLP-1-only receptor agonist. In the STEP-1 clinical trial, participants lost an average of 14.9% body weight on the maximum 2.4 mg dose over 68 weeks. Both medications are used alongside reduced-calorie diet and increased physical activity — results vary significantly between individuals.
- Mounjaro: dual mechanism, once-weekly, doses 2.5 mg to 15 mg
- Wegovy: single mechanism, once-weekly, doses 0.25 mg to 2.4 mg
- Both require 4+ weeks at each dose before titration
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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.
Which Medication Is Right for You — Prescriber Assessment
Neither Mounjaro nor Wegovy can be bought privately without a prescription from a UK-licensed prescriber, and a clinical assessment is mandatory. A prescriber will review your medical history, current medications, weight, height, and any weight-related health conditions to determine which medication — if either — is suitable for you personally.
Factors a prescriber may consider include contraindications, your response to similar medications, whether you have type 2 diabetes, and your individual health goals. Some people may be eligible for both; others may be recommended for one over the other; some may not be suitable for either at that time.
- Use our GLP-1 weight loss calculator to explore potential weight loss outcomes at different doses
- Your prescriber will make the final recommendation based on your individual assessment
- 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.
Can I buy Mounjaro privately without going through the NHS?
Yes. Mounjaro is available through GPhC-registered online pharmacies following an online clinical assessment with a UK-licensed prescriber. You do not need an NHS referral, but you do need a prescription. A prescriber will assess whether tirzepatide is suitable for you based on your health profile before a prescription is issued.
What's the main difference between Mounjaro and Wegovy?
Mounjaro is a dual GIP and GLP-1 agonist (two hormone pathways), while Wegovy is a GLP-1-only agonist (one pathway). Clinical trials showed Mounjaro resulted in slightly higher average weight loss, but both are effective. Individual response varies significantly — one may suit you better than the other.
Is one faster-acting than the other?
Both are titrated gradually from a starting dose, increasing every 4 weeks. Neither acts instantly. Mounjaro starts at 2.5 mg and Wegovy at 0.25 mg. Most people notice changes in appetite within 1–2 weeks, but steady weight loss typically emerges over weeks 4–8 as you stabilise on higher doses.
Will my prescriber choose which one I get?
Yes. Following your clinical assessment, the prescriber will recommend the medication they believe is most appropriate for your circumstances. This may be Mounjaro, Wegovy, another GLP-1 medication, or they may advise that medication is not suitable for you at this time. You cannot choose between them directly.
How do I know if I'm eligible to buy Mounjaro privately?
You're generally eligible if you have a BMI of 30 or above, or 27 or above with at least one weight-related health condition (diabetes, high blood pressure, sleep apnoea, cardiovascular disease). However, eligibility depends on your full medical history — the prescriber will confirm this during your assessment.
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.