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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Your Pharmacist's Role with Mounjaro in the UK
If you're prescribed Mounjaro through NHS tier 3 weight management services or privately in the UK, your community pharmacist plays a vital support role. They dispense your prescription, check for interactions with other medications, provide injection technique guidance, monitor for side effects, and answer questions about storage and usage. Understanding how pharmacists support Mounjaro treatment helps you get the most from your prescription and ensures safe, effective use alongside your reduced-calorie diet and increased physical activity.
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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.
How Pharmacists Support Mounjaro Prescriptions in the UK
Your community pharmacist is an essential part of your Mounjaro journey in the UK. When you collect your prescription, they check that Mounjaro is safe for you based on your medical history and other medications — particularly important since Mounjaro may reduce absorption of oral contraceptives and other oral medicines. Pharmacists verify correct storage (2–8°C in the refrigerator for unopened pens, or up to 30 days at room temperature after first use) and provide practical guidance on injection technique, rotation of injection sites (abdomen, thigh, or upper arm), and what to do if you miss a dose. They also monitor how you're tolerating the medication, noting common side effects like nausea, diarrhoea, and constipation, which typically reduce over time. Additionally, pharmacists can advise on timing Mounjaro injections consistently each week and discuss how it works as a dual GIP and GLP-1 receptor agonist to support appetite regulation. If you have concerns about side effects or interactions, your pharmacist is the first port of call before contacting your GP.
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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.
NHS Access and Your Pharmacist's Role
In the NHS, Mounjaro is dispensed through tier 3 specialist weight management services. Your specialist prescriber initiates treatment and manages dose escalation (starting at 2.5 mg, increasing every 4 weeks up to a maximum of 15 mg). Your community pharmacist then takes over the ongoing supply role, ensuring continuity between appointments. They flag any issues — such as side effects affecting adherence or medication interactions — back to your specialist team. Calculate your potential outcomes with our free GLP-1 weight loss calculator, which helps you understand projected results at different doses. Private prescriptions follow a similar pharmacist support model. Your pharmacist can also refer you to NHS services if you need additional support, and will advise on eligibility based on your BMI (30 or above, or 27+ with weight-related health conditions like type 2 diabetes or hypertension).
- 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.
What checks will my pharmacist do when I collect Mounjaro?
Your pharmacist will verify your prescription details, check for interactions with your other medications (especially oral contraceptives and diabetes drugs), confirm you understand storage requirements (2–8°C refrigerated), and provide injection guidance. They'll also ask about any side effects from previous doses and ensure you know how to recognise emergency symptoms like severe abdominal pain.
Can my pharmacist help if I'm experiencing Mounjaro side effects?
Yes. Report nausea, diarrhoea, constipation, or other side effects to your pharmacist first — they can advise on management strategies and timing adjustments. If side effects are severe or persistent, they'll recommend contacting your GP or specialist team. Most common side effects reduce after the first few weeks.
How does my pharmacist communicate with my NHS specialist team?
Your pharmacist has access to your prescription records and can flag concerns directly. They may contact your specialist if you report serious side effects, missed doses, or suspected interactions. Regular communication ensures your treatment stays on track and safe.
Will my pharmacist know about my tirzepatide dose schedule?
Yes. Your prescription shows your current dose and when you started. Your pharmacist will track your dose escalation schedule and can remind you when it's time to increase (typically every 4 weeks). They'll also help if you need to repeat a dose or pause treatment.
What's the difference between NHS and private pharmacist support for Mounjaro?
Both follow the same safety checks and storage guidance. NHS pharmacists work alongside tier 3 specialists; private pharmacists work with private prescribers. Private routes may offer faster access but follow identical pharmacy safety standards and GPhC regulations.
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.