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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Eggy Burps on Mounjaro — What You Need to Know
Eggy burps (sulfurous belching) are a well-documented side effect reported by some people using Mounjaro (tirzepatide). This uncomfortable symptom typically occurs early in treatment when starting the medication or increasing doses. Understanding what causes it, how long it lasts, and your options for accessing Mounjaro in the UK can help you make an informed decision about this prescription weight management injection. We'll cover the NHS route, private prescription options, and realistic cost expectations.
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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.
Why Eggy Burps Happen on Mounjaro and How to Manage Them
Eggy burps occur because Mounjaro (tirzepatide) slows how quickly food moves through your digestive system — a process called delayed gastric emptying. This allows food to ferment in the stomach longer, producing sulfurous gases that cause the distinctive rotten egg smell. This effect is temporary: most people report the symptom improves significantly within 2–4 weeks as your body adjusts to the medication.
To help manage eggy burps:
- Eat smaller, more frequent meals rather than large portions
- Choose easily digestible foods like lean proteins, vegetables, and whole grains
- Avoid high-fat and greasy foods, which slow digestion further
- Stay well hydrated — dehydration can worsen symptoms
- Take your injection on a consistent day each week
- Ginger tea or peppermint may help settle digestion
If burps persist beyond 4 weeks, contact your prescriber — they can assess whether a dose adjustment might help.
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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.
Accessing Mounjaro in the UK: NHS vs Private Options
NHS route: Mounjaro is available through specialist tier 3 weight management services, but you must be referred by your GP. Waiting lists vary significantly by region — some areas have waiting times of many months. Eligibility requires a BMI of 30 or above, or 27–29.9 with weight-related health conditions like type 2 diabetes or high blood pressure.
Private route: UK-licensed prescribers offer online consultations, usually costing £15–£40. If approved, you'll receive a prescription dispensed by a GPhC-registered pharmacy. The Mounjaro KwikPen costs typically range from £130–£320 per month depending on your dose. Starting on the 2.5 mg dose (weeks 1–4) costs less than maximum doses, and you'll titrate up over weeks with dose adjustments.
What to expect in a private online consultation: You'll answer detailed health questions about your weight, BMI, medical history, and current medications. The prescriber assesses your eligibility based on NHS criteria — you'll need a BMI of 27 or above with qualifying health conditions, or 30 or above. If approved, your prescription goes to a pharmacy which ships the KwikPen to your home. Avoid mentioning specific pharmacy names; focus on the clinical process. Most people receive their first pen within 3–5 working days.
- 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.
How long do eggy burps last on Mounjaro?
Most people report eggy burps improve significantly within 2–4 weeks as their digestive system adjusts. Some experience them only when starting or increasing doses. If burps persist beyond 4 weeks, speak to your prescriber about dose timing or adjustments.
Are eggy burps a sign Mounjaro isn't working?
No. Eggy burps are a common temporary side effect caused by slowed gastric emptying, not a failure of the medication. They don't indicate whether tirzepatide will be effective for weight loss — that takes several weeks to assess.
Can I get Mounjaro through the NHS in the UK?
Yes, Mounjaro is available through NHS specialist weight management services (tier 3). You'll need a GP referral and must meet eligibility criteria: BMI 30 or above, or 27–29.9 with weight-related health conditions. Waiting lists vary significantly by region.
How much does Mounjaro cost privately in the UK?
Private prescriptions typically cost £15–£40 per consultation. The Mounjaro KwikPen costs £130–£320 per month depending on your dose. Starting dose (2.5 mg) is usually cheaper than maximum doses. You'll titrate up over weeks following dose titration schedules.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, while Wegovy (semaglutide) is a GLP-1 only agonist. Both are once-weekly injections. Mounjaro typically shows slightly higher average weight loss in clinical trials, but individual results vary. Both require prescription and clinical assessment.
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.