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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Can I Drink Coffee on Mounjaro?
Yes, you can drink coffee while taking Mounjaro (tirzepatide), but you may need to be mindful of how your stomach responds. Many people taking this prescription weight management injection experience nausea and stomach sensitivity, particularly in the first few weeks. Coffee, especially on an empty stomach, can worsen these side effects. This guide covers what you need to know about caffeine and Mounjaro in the UK, plus how to access this medication and what it costs through NHS and private routes.
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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.
Coffee and Mounjaro — What You Should Know
Coffee itself is not contraindicated while taking Mounjaro, but caffeine can increase stomach irritation if you're already experiencing nausea or gastric sensitivity—common side effects during the first 4 weeks on any new dose. Best practice tips include:
- Drink coffee with food rather than on an empty stomach
- Start with smaller amounts to see how your stomach responds
- Consider switching to decaffeinated coffee if regular coffee causes discomfort
- Stay well hydrated—caffeine is a diuretic and Mounjaro side effects can include dehydration
- Avoid very hot or very strong coffee in the first weeks of starting or increasing your dose
Most people find their tolerance improves as their body adjusts to tirzepatide, typically after 4–8 weeks on a stable dose. If coffee consistently triggers nausea, it's worth discussing alternatives with your GP or prescriber. Your individual response depends on your dose level, how long you've been taking Mounjaro, and your personal sensitivity to caffeine and stomach irritants.
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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.
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Everything you need to understand your weight, explore medication options, and track your progress — completely free.
Mounjaro Cost and Access in the UK
On the NHS: Mounjaro is available through tier 3 specialist weight management services following referral from your GP. Access varies by region (integrated care board), and waiting lists can be several months to over a year in many areas. On the private route: Mounjaro is available through private online prescribing from UK-licensed prescribers, typically costing £149–£280 per month depending on your dose and provider. Private consultations are usually £20–£50 and take 10–15 minutes. You'll need to answer health questions, and a prescriber will assess whether tirzepatide is suitable based on your BMI, medical history, and any existing medications. Prescriptions are dispensed by GPhC-registered pharmacies and posted to you. Both routes require a valid prescription—Mounjaro is never available without clinical 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.
Is caffeine safe while taking Mounjaro?
Caffeine itself isn't unsafe on Mounjaro, but it may worsen nausea and stomach sensitivity, especially in your first weeks on the medication. Drinking coffee with food and starting with smaller amounts helps most people. If you experience persistent stomach discomfort, discuss alternatives with your GP or prescriber.
What's the cost of Mounjaro on the NHS in the UK?
Mounjaro is free on the NHS if prescribed through a tier 3 specialist weight management service, but access is limited by region and waiting lists. Your GP can refer you, but you'll likely wait weeks or months. Private prescription costs £149–£280 monthly depending on your dose.
How quickly can I access Mounjaro privately in the UK?
Private online consultation typically takes 10–15 minutes. If approved by the prescriber, your prescription is usually dispensed within 24–48 hours and posted to your address. You can start Mounjaro within days, much faster than NHS routes in most regions.
Do I need a prescription for Mounjaro in the UK?
Yes, Mounjaro is prescription-only medicine in the UK. You cannot buy it without a valid prescription from a licensed prescriber. Both NHS and private routes require clinical assessment to ensure it's safe and appropriate for you.
What's the difference between Mounjaro and Wegovy when it comes to cost?
Both are prescription-only. Private costs are similar (£129–£320/month depending on dose and provider). NHS access for both is through specialist weight management services with regional variation. Mounjaro is a dual GIP/GLP-1 agonist; Wegovy is GLP-1 only. Ask your prescriber which is suitable for you based on your health profile.
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