Sulfur burps on a GLP-1: what's known, and what isn't

What sulfur burps are

"Sulfur burps" isn't a medical term. It's the everyday name, spelled sulphur burps in the UK, for burps that smell of rotten eggs. A 2025 expert commentary on GLP-1 treatment in the journal Obesity Pillars describes them as eructation, the medical word for burping, "with hydrogen sulfide odor".⁸

Burping itself is ordinary. Mayo Clinic describes it as your body's way of pushing out excess air from your upper digestive tract, and says most belching is caused by swallowing excess air, which often never even reaches the stomach.¹⁰

The smell is the less understood part. Hydrogen sulfide, the gas with the familiar rotten-egg smell, is the usual suspect, but the only measurement study we found looked at gas from the other end: in 1998, researchers collected flatus from 16 healthy people and found hydrogen sulfide was the main sulfur gas: the more of it there was, the worse the smell.⁹ We found no study that has measured hydrogen sulfide in burps, and none that has measured burp smell in people taking GLP-1 medicines.

What the labels report: burping on GLP-1 medicines

No label records smell, so there is no "sulfur burps" rate for any medicine. What the labels do record is burping of any kind, listed as eructation, and it was more common than on placebo with each of these medicines. Every row comes from different trials in different people, so read each one on its own.

Figures from each medicine's US prescribing information, section 6.1, apart from the Wegovy pill: its label gives no separate figure and says common reactions with the tablets were similar to those in the injection trials.⁴ The labels say side-effect rates from different medicines' trials can't be compared directly, and the doses shown are trial groups; your prescriber sets yours.² The trials that compared tirzepatide with semaglutide directly are covered in semaglutide vs tirzepatide.

Do sulfur burps go away on a GLP-1?

The labels say little about timing. Wegovy's is the only one that ties burping to a stage of treatment: it lists burping among stomach reactions that "were most frequently reported during dosage escalation".⁴ The Mounjaro and Zepbound labels describe that pattern for nausea, vomiting and diarrhea, not for burping, and no label says how long burping lasts.^1,2

So nobody can promise yours will pass, or say when. What helps is noting when it started and whether it's changing, which is useful to your prescriber either way. Our pages on Mounjaro side effects and Zepbound side effects put burping alongside the rest of each label.

Do GLP-1s cause sulfur burps? What's known, and what's a guess

You'll read one explanation almost everywhere: the medicine slows your stomach, food sits and ferments, and hydrogen sulfide builds up. Some links in that chain are established. The chain as a whole has never been shown.

The 2025 commentary in Obesity Pillars lists sulfur burps among "poorly understood adverse effects" that "warrant mechanistic investigation". Its verdict on the three explanations on the right: "direct evidence is lacking".⁸

Easing sulfur burps: what reputable sources suggest

These are Mayo Clinic's tips for reducing burping, and most are about swallowing less air. None has been tested for sulfur burps in people taking a GLP-1 medicine, so treat them as general advice and ask your care team whether they suit you.¹⁰

• Eat and drink slowly. Taking your time can help you swallow less air; Mayo Clinic suggests making meals relaxed occasions rather than eating on the run.¹⁰
• Skip fizzy drinks and beer. Carbonated drinks and beer release carbon dioxide gas.¹⁰
• Skip gum and hard candy. You swallow more often than normal, and part of what you swallow is air.¹⁰
• Don't smoke. When you inhale smoke, you also swallow air.¹⁰
• Check your dentures. Poorly fitting dentures can make you swallow excess air as you eat and drink.¹⁰
• Take a short walk after eating. Mayo Clinic says getting moving may help.¹⁰

If heartburn or reflux comes with the burping, mention that too: Mayo Clinic notes that acid reflux can sometimes cause excessive belching.¹⁰

Food, protein and over-the-counter remedies

Lists of sulfur-rich foods to avoid, such as eggs, meat, broccoli and cabbage, are common online. No study has tested whether cutting them out helps sulfur burps in people taking a GLP-1 medicine, and some of them, such as eggs and meat, are important sources of protein. If one food seems to set things off, note it, and talk to your care team or a dietitian before cutting out whole groups of food. Our GLP-1 food tracker guide covers keeping a simple food and protein record.

You'll also see over-the-counter remedies recommended. Handle doesn't recommend medicines: ask a pharmacist or your prescriber, who knows what else you take, before trying one. And any change to your GLP-1 medicine itself is a decision for you and your prescriber.

Red flags: when burping needs a call

Mayo Clinic says burping, gas and bloating often resolve on their own or with simple changes, and that when they're the only symptoms, they rarely represent any serious underlying condition.¹⁰ What matters is what comes with them. The urgent list below quotes the Medication Guides and the NHS directly.

Sulphur burps with diarrhoea: what the NHS says

Egg-smelling burps aren't always about your medicine. The NHS lists "smelly burps – they may smell like eggs" among the main symptoms of giardiasis, an infection, alongside smelly diarrhoea, tummy pain or cramps, farting, bloating and weight loss.¹¹

It says to ask for an urgent GP appointment or get help from NHS 111 if "you have had diarrhoea for more than 7 days, or your diarrhoea gets worse quickly", or if "you have bloody diarrhoea or bleeding from your bottom".¹¹ Outside the UK, call your doctor or care team.

When to see your doctor about burping

Mayo Clinic advises seeing a healthcare professional if symptoms don't improve with simple changes, particularly if you also notice diarrhea, persistent or severe belly pain, bloody stools, changes in the color or frequency of stools, losing weight without trying, chest discomfort, or loss of appetite or feeling full quickly.¹⁰

Some of those, such as eating less or feeling full sooner, are also what GLP-1 medicines are prescribed to do. Handle can't tell which is which, and neither can a web page, so tell your prescriber about anything new, getting worse or not going away.

Tracking sulfur burps for your prescriber

By the time of an appointment, burping is easy to forget, or to sum up as "a lot", which is hard for anyone to act on. A daily yes or no, kept on the same record as your doses, turns that into something concrete: how often, since when, and whether it's changing.

Note what else was going on, such as meals, fizzy drinks or other symptoms, without trying to work out the cause yourself. Our GLP-1 side effect tracker guide covers what to record, and our guide to preparing for a GLP-1 doctor appointment covers what to bring.

Questions to ask your prescriber

1. Could the burping I'm noticing be from my medicine, or is it worth checking for something else?
2. Which symptoms alongside it should I call you about, and which can wait until my next appointment?
3. Could a dietitian help with my meals without me cutting back on protein?
4. Could any of my other medicines or supplements be making burping or reflux worse?
5. If I want to try an over-the-counter remedy, which is safe with the other medicines I take?

For each medicine's full label picture, see Ozempic side effects, Wegovy side effects, Foundayo side effects and our overview of GLP-1 side effects.