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 vs Wegovy — What's the Difference?
Sulphur burps (rotten egg-smelling burps) are a recognised side effect of GLP-1 and GIP/GLP-1 receptor agonist medications like Mounjaro and Wegovy. Both medications can cause this symptom, though it's not assured and individual experience varies widely. Understanding the mechanism, frequency, and management strategies can help you make an informed decision about which medication might suit you. This guide compares both medications factually and explains what prescribers and patients need to know about this particular side effect in UK clinical practice.
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.
How Mounjaro and Wegovy Cause Sulphur Burps — Mechanism Comparison
Sulphur burps occur because GLP-1 and tirzepatide (Mounjaro's active ingredient) slow gastric emptying — the speed at which food moves from your stomach into your small intestine. When food sits in the stomach longer, bacterial fermentation increases, producing hydrogen sulphide gas. This gas escapes as burps with a characteristic rotten egg smell.
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, which may intensify this effect compared to GLP-1-only medications. Wegovy (semaglutide) is a GLP-1 agonist alone, potentially causing a slightly lower incidence of sulphur burps, though clinical trial data does not directly compare this side effect between the two.
- Both slow stomach emptying as part of their mechanism
- Individual variation in gastric motility affects symptom severity
- Dietary choices significantly influence frequency and intensity
- Symptom typically improves over time as tolerance develops
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 Strategies and Prescriber Guidance
If you experience sulphur burps on either Mounjaro or Wegovy, practical management includes eating smaller, more frequent meals, avoiding fatty or high-sulphur foods (eggs, meat, cruciferous vegetables, onions, garlic), staying hydrated, and taking a slow digestive pace. Many patients report symptoms improve significantly after 4–8 weeks as the body adapts.
If sulphur burps persist or severely impact quality of life, inform your prescriber — they may adjust your dose, slow your titration schedule, or explore whether a different medication might suit you better. Neither medication works universally for all patients, and prescriber guidance should always take precedence over online information. Use our free GLP-1 weight loss calculator to compare potential outcomes with different medications, and discuss any side effect concerns with your clinical team.
- 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.
Do all patients on Mounjaro experience sulphur burps?
No. Sulphur burps are common but not universal. Clinical trial data shows many patients experience no sulphur burps at all, whilst others report mild to moderate symptoms. Individual variation depends on gastric motility, diet, dose, and how long you've been taking the medication. Symptoms often improve over weeks as tolerance develops.
Is Wegovy better than Mounjaro for avoiding sulphur burps?
There is no definitive clinical comparison showing Wegovy causes fewer sulphur burps than Mounjaro. Both medications slow gastric emptying and can trigger this side effect. Individual response varies widely — some people on Wegovy experience significant sulphur burps whilst others on Mounjaro have none. Your prescriber assesses suitability based on your overall health, not just this one side effect.
How long do sulphur burps last on GLP-1 medication?
Sulphur burps typically develop within the first few weeks of starting or escalating dose, and many patients report improvement after 4–8 weeks as the body adjusts. Some continue to experience occasional symptoms throughout treatment. Persistent symptoms should be discussed with your prescriber — dose adjustment or medication change may help.
What foods trigger sulphur burps on Mounjaro or Wegovy?
High-sulphur foods are common triggers: eggs, red meat, poultry, dairy, cruciferous vegetables (broccoli, cabbage, sprouts), onions, garlic, and processed foods. Fatty meals also delay stomach emptying and worsen symptoms. Keeping a food diary helps identify your personal triggers. Eating slowly and in smaller portions also reduces symptom severity.
Should I stop taking Mounjaro or Wegovy if I get sulphur burps?
No — do not stop without prescriber guidance. Sulphur burps are a known, usually temporary side effect that often improves with time and dietary adjustment. If symptoms severely impact your quality of life, speak to your prescriber about dose adjustment, slower titration, or exploring alternative medications. Your prescriber will help you weigh benefits against side effects.
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.