If you've started Mounjaro and suddenly find yourself dealing with burps that smell like rotten eggs, you're not alone. Sulphur burps are frequently reported by people using tirzepatide for weight management, even though they weren't specifically measured in clinical trials.

Sulphur burps happen because Mounjaro slows your digestion, giving gut bacteria more time to ferment food and produce smelly hydrogen sulphide gas. They're unpleasant but harmless, and usually improve within 2–4 weeks as your body adjusts to each dose. Avoiding trigger foods and eating smaller meals can help reduce them.

Key takeaways

Sulphur burps on Mounjaro are caused by slowed digestion, which gives gut bacteria more time to ferment (break down) food and produce hydrogen sulphide gas

They're unpleasant but harmless, and typically improve within 2–4 weeks as your body adjusts to each dose

Eating smaller meals, avoiding high-sulphur foods (eggs, red meat, cruciferous vegetables), and staying hydrated can reduce symptoms

Contact your GP if sulphur burps are accompanied by severe pain, vomiting, fever, or don't improve after several weeks

What are sulphur burps?

Sulphur burps are burps that carry a distinctive rotten egg smell. The odour comes from hydrogen sulphide (H₂S), a gas naturally produced by gut bacteria when they break down sulphur-containing foods. It's the same compound that gives rotten eggs their characteristic smell.

A simplified diagram showing a stomach with food inside, arrows indicating slowed movement, and small icons representing bacterial activity producing gas bubbles.

Normally, food moves through your digestive system quickly enough that this gas doesn't build up to noticeable levels. But Mounjaro slows down how fast your stomach empties its contents into your small intestine, affecting your metabolism and the pace of digestion. When food sits in your stomach and intestines for longer, gut bacteria have more time to ferment it, producing more hydrogen sulphide gas.

Why does Mounjaro cause sulphur burps?

Tirzepatide (the active ingredient in Mounjaro) is a dual GLP-1 and GIP receptor agonist. It works on two appetite-regulating hormone receptors instead of one. Originally developed for type 2 diabetes to help control blood sugar levels, tirzepatide was found to produce significant weight loss in clinical trials. By mimicking these hormones, the medication helps you feel fuller for longer, reduces appetite, and affects your metabolism. This is how it supports weight loss. However, these same hormones also slow down how quickly food leaves your stomach (known as gastric emptying).

This slower digestion is beneficial for appetite control, but it creates the perfect environment for bacterial fermentation. Foods containing sulphur compounds sit around longer in your gut, giving bacteria extra time to break them down and produce hydrogen sulphide.

The effect is often more noticeable when you first start Mounjaro or after moving up to a higher dose. Your digestive system needs time to adapt to the medication's effects, and during this adjustment period, symptoms like sulphur burps tend to be more pronounced.

Sulphur burps are part of the broader digestive side effects that many people experience on Mounjaro, alongside nausea, [bloating](/mounjaro/side-effects/digestive/bloating) issues, and painful stomach cramps.

Foods that make sulphur burps worse

Certain foods are higher in sulphur compounds than others, and eating these whilst on Mounjaro can trigger or worsen sulphur burps. If you're struggling with eggy burps, consider cutting back on

Eggs (particularly the yolks, which are high in sulphur)
Red meat and poultry (contain sulphur-containing amino acids)
Garlic and onions (naturally high in sulphur compounds)
Cruciferous vegetables (broccoli, cabbage, cauliflower, and Brussels sprouts)
Dairy products (especially cheese)
Beer and wine (fermentation adds sulphur compounds)
Legumes (beans and lentils)

An infographic showing foods to limit for sulphur burps: eggs, red meat, garlic, onions, broccoli, cheese, and beer, each with a small icon.

You don't necessarily need to eliminate these foods entirely. Sometimes just reducing portion sizes or spacing them out differently can make a noticeable difference. Keep a food diary for a week or two to identify your personal triggers, as what causes problems for one person might be fine for another.

As part of a balanced diet, try to include plenty of fibre from low-sulphur sources like oats, rice, and most fruits. Fibre helps keep your digestive system moving, which may reduce the time food spends fermenting in your gut. However, increase fibre gradually. Adding too much too quickly can temporarily worsen bloating and gas.

How to reduce sulphur burps on Mounjaro

Peppermint tea after meals

Fresh ginger steeped in hot water

Ginger biscuits (in moderation)

Ginger supplements

When do sulphur burps go away?

For most people, sulphur burps improve after the first few weeks on Mounjaro. Your digestive system gradually adapts to the medication's effects, and the bacterial fermentation that causes these burps tends to settle down.

That said, you might notice a temporary return of symptoms each time you increase your dose. The pattern typically repeats: worse for a week or two after the dose change, then gradually improving as your body adjusts.

If sulphur burps persist for more than a few weeks at the same dose, or if they're severe enough to affect your quality of life, discuss it with your prescriber. They might suggest staying at your current dose for longer before increasing, or exploring other ways to manage the symptom. Whilst sulphur burps are among the more common short-term side effects, serious long-term side effects from Mounjaro are rare. Most digestive symptoms improve as your body adjusts to the medication.

Sulphur burps and other digestive symptoms

Sulphur burps rarely show up in isolation. They're often accompanied by other digestive side effects that stem from the same cause: Mounjaro's effect on how quickly food moves through your system.

You might also experience:

Heartburn or acid reflux
Bad breath (often related to the same gases causing sulphur burps)
abdominal gas and bloating and excessive gas
Nausea, especially after eating
stomach cramping or discomfort
Diarrhoea, particularly during dose escalation
Tiredness or low energy levels, especially if you're eating less

Some people also notice hair loss as a separate side effect, which is related to rapid weight loss and reduced calorie intake rather than digestive changes.

The good news is that managing one symptom often helps with others. The dietary changes that reduce sulphur burps (eating smaller meals and avoiding trigger foods) typically improve bloating and nausea too.

When to talk to your doctor

Contact your GP or prescriber

Sulphur burps on their own are annoying but not dangerous. However, certain symptoms alongside them might indicate something that needs medical attention. A checklist infographic showing warning signs that need medical attention: severe abdominal pain, persistent vomiting, blood in vomit or stool, fever, and symptoms not improving. Contact your GP or prescriber if you experience:

Severe or persistent abdominal pain, especially if it radiates to your back (possible sign of pancreatitis)
Vomiting that won't stop
Blood in your vomit or stool
Unexplained weight loss beyond what you'd expect from the medication
Fever alongside your digestive symptoms
Signs of gallbladder problems such as pain in your upper right abdomen after eating fatty foods
Sulphur burps that persist for several weeks without any improvement

These symptoms could indicate conditions like gastritis, a stomach infection, or other issues that need proper medical evaluation. Mention any concerns about blood pressure or other health changes during your regular check-ins.

Frequently asked questions

Can I take anything for sulphur burps on Mounjaro?

Over-the-counter simethicone products (like Wind-eze) can help break up gas bubbles. Peppermint tea or ginger may also provide relief. Check with your pharmacist that these are suitable alongside any other medications you take.

Are sulphur burps a sign that Mounjaro is working?

Not specifically. Sulphur burps indicate that Mounjaro is slowing your digestion, which is one of its effects, but they're not a measure of how well the medication is working for weight loss. Many people achieve good results without experiencing significant sulphur burps.

Should I stop taking Mounjaro because of sulphur burps?

Don't stop your medication without discussing it with your prescriber. Sulphur burps, whilst unpleasant, typically improve over time. If they're significantly affecting your quality of life, your prescriber may suggest adjusting how quickly you move through the dose increases.

Do sulphur burps mean I have a stomach infection?

Usually not. Sulphur burps on Mounjaro are typically caused by slowed digestion rather than infection. However, if burps are accompanied by fever, severe pain, vomiting, or don't improve over time, see your GP to rule out other causes.

Are sulphur burps and bad breath connected?

Yes, they often are. The same hydrogen sulphide gas that causes sulphur burps can also contribute to bad breath. Managing one often helps with the other. Staying hydrated, eating smaller meals, and good oral hygiene can all help.

Are sulphur burps worse at certain times of day?

Many people notice sulphur burps are worse in the morning (after food has sat in the stomach overnight) or in the evening after larger meals. Eating your largest meal earlier in the day and keeping evening meals light may help reduce symptoms.

Will switching injection sites help with sulphur burps?

No, sulphur burps are caused by how tirzepatide affects your digestive system, not by the injection site. Changing where you inject won't reduce digestive side effects.

Can probiotics help with sulphur burps on Mounjaro?

Some people find probiotics helpful for digestive symptoms, though there's limited research specifically on sulphur burps. If you want to try probiotics, choose one containing Lactobacillus or Bifidobacterium strains. Speak to your pharmacist for recommendations.

What to do next

If you're experiencing sulphur burps on Mounjaro, start by adjusting your diet. Eat smaller meals, reduce high-sulphur foods, and keep a food diary to identify your triggers. Give your body a few weeks to adjust, as symptoms typically improve with time.

If sulphur burps persist or significantly affect your quality of life, speak to your GP or prescriber. They can review your treatment plan and advise on whether adjusting your dose schedule might help. For more general advice on managing digestive discomfort, see the NHS guidance on indigestion.

Sources

Mounjaro summary of product characteristics – Electronic Medicines Compendium
NHS guidance on indigestion and heartburn – NHS
NHS guidance on heartburn and acid reflux – NHS
SURMOUNT-1 trial results – New England Journal of Medicine
NICE technology appraisal TA924: Tirzepatide for treating overweight and obesity – National Institute for Health and Care Excellence