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
Free tracker included with every download this week
Mounjaro Sulphur Burps — What You Need to Know
Sulphur burps (also called rotten egg burps) are a possible side effect some people experience when taking Mounjaro (tirzepatide). This is a GIP and GLP-1 receptor agonist injection used for weight management in the UK. The burps are caused by how the medication slows stomach emptying and affects gut bacteria. While unpleasant, sulphur burps are usually temporary and manageable. If you're considering Mounjaro or currently taking it, understanding this side effect can help you know what to expect and how to manage it effectively.
10,000+ calculations today · NHS-aligned thresholds · 100% free
Calculate Your BMI Instantly
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 Sulphur Burps Happen on Mounjaro
Mounjaro works by activating GIP and GLP-1 receptors, which slows how quickly food moves through your stomach (gastric emptying). When food sits in your stomach longer, it ferments slightly and produces gases including hydrogen sulphide—the compound that creates that distinctive rotten egg smell. Additionally, the medication can alter your gut bacteria composition and digestive processes, which contributes to excess gas production.
Sulphur burps are reported as a possible side effect in clinical trials and real-world use. They're more common when you first start Mounjaro or increase your dose, particularly in the first 4–8 weeks. The effect typically reduces as your body adjusts to the medication. Dietary factors—such as eating sulphur-rich foods like eggs, meat, and cruciferous vegetables—can make sulphur burps more noticeable. Individual experiences vary; not everyone on Mounjaro experiences this side effect.
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.
Managing Sulphur Burps — Practical Tips
Dietary adjustments: Temporarily reduce intake of high-sulphur foods (eggs, red meat, broccoli, cabbage, onions). Eat smaller, more frequent meals rather than large meals. Stay well hydrated and eat slowly to aid digestion.
Other management strategies: Take a short walk after meals to support stomach emptying. Use over-the-counter digestive aids like simethicone (Infacol) if your GP approves—these can help reduce gas. Peppermint tea may also provide relief. If sulphur burps persist beyond 8–12 weeks or significantly impact your quality of life, contact your GP or the prescriber who issued your Mounjaro. They can assess whether continuing the medication is appropriate or whether a dose adjustment is needed.
- 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 sulphur burps a sign Mounjaro isn't working?
No. Sulphur burps are a side effect of how the medication affects stomach emptying and gut bacteria, not an indicator of efficacy. Clinical trials and UK patients show weight loss benefits regardless of whether sulphur burps occur. Many people experience no sulphur burps at all.
How long do sulphur burps last on Mounjaro?
Most people find sulphur burps improve after 4–12 weeks as their body adjusts. Some notice improvement after just a few weeks. If they persist beyond 12 weeks, discuss with your GP or prescriber about management strategies or potential dose adjustments specific to your situation.
Can I stop Mounjaro if sulphur burps are too bothersome?
Do not stop Mounjaro abruptly without medical guidance. Instead, contact your GP or the prescriber who prescribed it. They can discuss whether continuing is appropriate, whether dietary changes help, or whether a different medication might suit you better based on your individual health profile.
Do sulphur burps mean I have a stomach problem?
Sulphur burps on Mounjaro are a temporary medication side effect, not a sign of infection or serious stomach disease. However, if you develop severe abdominal pain, persistent vomiting, or other concerning symptoms, seek medical attention promptly as these may indicate pancreatitis or other complications requiring urgent care.
Will sulphur burps come back if I increase my Mounjaro dose?
It's possible, as higher doses have a stronger effect on stomach emptying. Many people experience milder symptoms when increasing doses gradually (the standard dose titration from 2.5 mg to 15 mg). Your prescriber will monitor your tolerability and adjust your dose schedule accordingly.
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.