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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Mounjaro Eggy Burps — What You Need to Know
Eggy burps are a side effect some people experience when taking Mounjaro (tirzepatide), particularly in the early weeks of treatment. This unpleasant symptom — characterised by a sulphur-like taste when burping — may occur because Mounjaro slows gastric emptying, allowing food to spend more time in the stomach. For most people, eggy burps tend to reduce or disappear as the body adjusts to the medication. Understanding why this happens and how to manage it can help you decide whether Mounjaro is right for you.
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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 Do Eggy Burps Happen on Mounjaro?
Eggy burps occur because Mounjaro (tirzepatide) is a GIP and GLP-1 receptor agonist — it works by slowing how quickly food leaves your stomach (gastric emptying). When food stays in the stomach longer, bacteria naturally present in your digestive system ferment the food, producing hydrogen sulphide gas. This gas creates the distinctive eggy or sulphur-like smell when you burp. This effect is particularly noticeable in the first few weeks of starting Mounjaro or after a dose increase. The good news: most people find eggy burps diminish significantly within 2–4 weeks as their body adjusts to the medication. Some people never experience them at all. The severity varies widely between individuals and depends on diet, food choices, and how quickly your stomach adapts to the slower gastric emptying.
- More common in the first 4 weeks of starting or increasing your Mounjaro dose
- Related to slower food digestion, not a sign of harm
- Typically improves as your body adjusts
- Can be managed through dietary choices
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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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Managing Eggy Burps — Practical Tips
If you experience eggy burps on Mounjaro, several strategies may help. Avoid trigger foods — eggs, onions, garlic, cruciferous vegetables (broccoli, cabbage, Brussels sprouts), and high-protein foods can make sulphur production worse. Eat smaller, more frequent meals and chew food thoroughly to reduce the burden on your stomach. Stay hydrated and consider drinking ginger tea or peppermint tea, which may support digestion. If eggy burps persist beyond 4–6 weeks or are severely affecting your quality of life, discuss this with your prescriber — they can assess whether continuing Mounjaro is right for you, or discuss adjustments. Remember: this is a common, temporary side effect, not a sign that something is wrong.
- Avoid eggs, onions, garlic, and sulphur-rich vegetables temporarily
- Eat smaller meals and chew thoroughly
- Stay hydrated throughout the day
- Try ginger or peppermint tea after meals
- Speak to your prescriber if symptoms persist beyond 4–6 weeks
- 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.
Are eggy burps a sign that Mounjaro isn't working for me?
No. Eggy burps are a common side effect related to how Mounjaro slows gastric emptying — they are not connected to whether the medication is helping with weight management. Most people find eggy burps improve within 2–4 weeks as their body adjusts. If you're concerned about your response to Mounjaro, discuss this with your prescriber rather than stopping the medication.
How long do eggy burps last on Mounjaro?
For most people, eggy burps are most noticeable in the first 2–4 weeks and gradually reduce as the body adjusts to the medication. Some people experience them for longer, whilst others never experience them. If they persist beyond 6 weeks, speak to your prescriber about management strategies or whether a dose adjustment might help.
Is there a difference between eggy burps on Mounjaro and Wegovy?
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) slow gastric emptying, so both can cause eggy burps. Mounjaro is a dual GIP and GLP-1 agonist, whilst Wegovy is a GLP-1 agonist only. Some people report eggy burps are slightly more common with Mounjaro, but individual experiences vary greatly. Speak to your prescriber about which medication might be more suitable for you.
Can I prevent eggy burps before they start?
You can't completely prevent them, but being mindful of diet from day one may help reduce severity. Avoid eggs, onions, garlic, and cruciferous vegetables in your first few weeks on Mounjaro. Eat smaller meals, stay hydrated, and chew food thoroughly. Most people find symptoms resolve naturally without specific prevention strategies.
Should I stop taking Mounjaro if I get eggy burps?
Eggy burps alone are not a reason to stop Mounjaro — they are a temporary, manageable side effect that improves for most people within weeks. If you're experiencing severe side effects or the burps are significantly affecting your quality of life, discuss options with your prescriber. They can advise whether continuing, adjusting your dose, or switching to an alternative like Wegovy would be more suitable for you.
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