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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Switching Your Mounjaro Provider in the UK
If you're currently taking Mounjaro (tirzepatide) and considering switching providers, it's important to understand your options and what the process involves. Whether you're moving between NHS specialist services and private prescribing, or switching between private providers, each route has different costs, timelines, and eligibility requirements. This guide explains how to safely transition your Mounjaro prescription in the UK, what to expect during the switch, and how costs compare between NHS and private access.
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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.
Understanding Your Mounjaro Provider Options in the UK
In the UK, Mounjaro (tirzepatide) is available through two main pathways: NHS specialist weight management services and private online prescribing.
- NHS route: Prescribed through tier 3 or 4 specialist weight management services following GP referral. Free at point of use but involves longer waiting times and variable regional availability.
- Private route: Prescribed following an online clinical assessment with a UK-licensed prescriber. Available without NHS referral, typically faster access, but requires payment per prescription.
If you're currently on Mounjaro through one route and want to switch to another, the process depends on your current dose, medical history, and which provider you're moving to. Your GP should be informed of any changes to ensure continuity of care and monitoring. Never stop Mounjaro suddenly or self-switch doses without clinical guidance—your prescriber will advise on the safest transition method based on your individual health profile.
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.
Private Mounjaro Costs and the Online Prescription Process
Private Mounjaro prescriptions in the UK typically cost between £129 and £320 per month, depending on your dose and the prescribing provider. Costs are higher at maximum doses (15 mg) and lower at starting doses (2.5 mg). The online consultation process is straightforward: you complete a health questionnaire, a UK-licensed prescriber reviews your information, and if approved, your prescription is dispensed by a GPhC-registered pharmacy.
Before switching providers, check that your new provider offers the dose you're currently on and confirm their pricing. If switching from NHS to private, your current dose information will be helpful—bring any recent prescription records or a letter from your NHS specialist. Most private providers can begin treatment within 5–7 working days of approval.
- 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've completed your NHS specialist assessment, you can switch to private prescribing at any point. Inform your GP of the change. Bring your NHS prescription information to your private prescriber so they can continue at your current dose without interruption. There's no waiting period—private providers typically dispense within a week of approval.
What if I'm switching doses when changing providers?
If your current provider was titrating your dose, your new provider will have access to your prescription history. Provide them with details of your current dose and how long you've been on it. They'll determine whether to continue titration at the same schedule or adjust based on your medical history and response so far.
Is there a waiting time to switch providers?
NHS to private switch is typically immediate once your private prescription is approved (5–7 working days). Switching between private providers is also quick—usually within a week. Switching from private to NHS involves a GP referral and can take several months depending on your local ICB and waiting lists.
Will my weight loss progress be affected if I switch providers?
No. Mounjaro's effectiveness depends on the dose and your adherence, not the provider. Your weight loss should continue at a similar rate as long as you maintain the same dose and lifestyle changes. Your new provider may review your progress and adjust your dose if needed based on your results so far.
Can I use a MyWeightCheck BMI calculator to track progress during a provider switch?
Yes. Our free BMI calculator on this page helps you monitor your progress throughout your treatment journey, whether you're switching providers or continuing with the same one. Track your starting weight, current weight, and BMI to measure your response to tirzepatide regardless of which provider prescribes it.
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.