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 Mounjaro Providers in the UK
If you're currently taking Mounjaro (tirzepatide) and need to switch providers — whether moving from NHS to private, between private pharmacies, or changing prescribers — it's important to understand the process and how to maintain safe, continuous care. This guide explains your options and what you need to know about switching providers in the UK.
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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.
NHS to Private Mounjaro Switch — What You Need to Know
Switching from an NHS specialist weight management service to a private provider is possible but requires careful planning. Your NHS prescriber will not continue prescribing once you move to private care — you'll need a new prescription from a UK-licensed private prescriber.
- Your current dose and injection history should be documented in your NHS records — request this before leaving
- A private prescriber will need to assess you clinically before issuing a new prescription, even if you're already stabilised on a dose
- There is typically no gap in treatment if you plan the switch carefully — arrange your private prescription before your NHS supply runs out
- Your GP can provide medical history and current medication records to support the assessment process
- Costs differ significantly: NHS is free through specialist services; private typically ranges from £129–£320 monthly depending on dose
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.
Switching Between Private Providers or Prescribers
Changing between private prescribers or online pharmacies is more straightforward than NHS-to-private switches. You'll need a new prescription from your new provider, but the process is typically faster since you already have clinical history and current dose documentation.
- Gather your current prescription, dose history, and any side effect notes from your existing provider
- Inform your new provider of your current tirzepatide dose to ensure continuity — dose changes should be managed by your prescriber, not made independently
- Most private providers can issue a prescription within 24–48 hours following assessment
- Use our GLP-1 weight loss calculator to track your progress across provider switches
- 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 my GP prescribe Mounjaro if I leave NHS specialist services?
No. GPs do not typically prescribe Mounjaro — it remains a specialist medication. If you leave NHS specialist services, you'll need to switch to a private prescriber. Your GP can provide your medical records to support a private assessment, but cannot issue the prescription themselves.
Will I lose continuity of care if I switch providers?
Not necessarily, if you plan carefully. Request your dose history, injection dates, and side effect notes from your current provider. Share this with your new provider to ensure they understand your current treatment journey. Many private prescribers use similar assessment and monitoring protocols.
What if I'm in the middle of dose titration when I switch?
Inform your new provider immediately of your current dose and titration schedule. They may continue your existing plan or adjust it based on their assessment. Never skip doses or change your dose timing without guidance from your new prescriber — continuity of your injection schedule is important.
How long does it take to get a new Mounjaro prescription from a private provider?
Most private prescribers complete an online assessment and issue a prescription within 24–48 hours. Your prescription then goes to a GPhC-registered pharmacy for dispensing. Plan ahead to avoid gaps in your treatment.
Is Mounjaro more expensive with a private provider than NHS?
Yes. Through NHS specialist services, Mounjaro is free. Private providers charge approximately £129–£320 per month depending on your dose. Some providers offer subscription discounts. Compare costs across providers before switching — prices vary.
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.