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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How to Switch Your Mounjaro Provider in the UK
Yes, you can switch Mounjaro providers in the UK — whether moving from NHS specialist services to private prescribing, or changing between private providers. The process depends on which tier of care you're currently accessing and whether there are any clinical reasons your prescriber may recommend staying with your current provider. This guide explains your options, what happens to your prescription, and how to make the switch safely.
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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.
Understanding Your Mounjaro Provider Options in the UK
In the UK, you can access tirzepatide (Mounjaro) through two main pathways: NHS specialist tier 3 weight management services, or private prescribing via GPhC-registered pharmacies following an online clinical assessment.
- NHS route: Prescription issued by a specialist tier 3 weight management service after referral from your GP. Regional availability varies significantly — waiting lists can be months to years in some areas.
- Private route: Online consultation with a UK-licensed prescriber, prescription issued if clinically appropriate, dispensed by a registered pharmacy. No NHS referral needed. Typically faster access than NHS services.
- Switching between private providers: You can move between private prescribers at any time, though your new prescriber will need to assess your suitability again.
Your current Mounjaro KwikPen dose and treatment history can be shared with your new provider to ensure continuity of care.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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.
What Happens When You Switch Providers?
When switching providers, your new prescriber will review your medical history, current dose, and response to treatment. They will likely continue your existing dose if you're managing well, or may adjust based on your progress.
- Prescription continuity: Your new provider issues prescriptions for future doses — you don't need to restart from a lower dose unless clinically indicated.
- Storage and supply: Ensure you have adequate Mounjaro in stock during the transition — there may be a short gap between prescribers.
- NHS to private switch: Once you move to private prescribing, you'll no longer access Mounjaro through NHS services. Any future NHS referral would require starting the assessment process again.
- Private to NHS switch: This is typically only possible by re-entering the NHS tier 3 pathway through your GP, with waiting lists applying.
Use our free GLP-1 weight loss calculator and BMI calculator to track your progress across the switch, ensuring your new provider has current baseline data.
- 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 switch from NHS Mounjaro to private prescribing?
Yes. Once you decide to move to private prescribing, inform your NHS specialist service and arrange your first private prescription. You won't need NHS referral again for private prescribing, though you may experience a gap in supply during the transition. Your medical history and current dose can be shared with your private prescriber.
What information do I need to provide my new Mounjaro provider?
Your new prescriber will need: current dose and injection frequency, date you started Mounjaro, any side effects you've experienced, weight loss progress to date, current weight and BMI (use our free BMI calculator for this), any other medications you take, and relevant medical history. This ensures safe continuity of care.
Will I need to restart at a lower Mounjaro dose when switching providers?
No — if you're managing well on your current dose, your new prescriber will typically continue it. Doses are only adjusted if clinically indicated (e.g., persistent side effects or inadequate response). Restarting titration is not standard practice for established patients switching providers.
What's the difference between switching to Mounjaro vs Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist, whilst Wegovy (semaglutide) is a GLP-1 agonist only. Clinical trials suggest Mounjaro may produce slightly higher average weight loss, though individual results vary. Any switch between medications requires prescriber assessment and should not be done independently.
How long does it take to get a prescription from a new Mounjaro provider?
Private providers typically issue prescriptions within 24–48 hours of online consultation completion. NHS services have longer waiting times. Ensure you have current Mounjaro stock before switching to avoid gaps in your weekly injections, as missing doses may affect your treatment progress.
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.