Sulfur Burps on Zepbound, Wegovy & Mounjaro: Gut Causes

Sulfur burps on Zepbound, Wegovy, Mounjaro or Ozempic are burps that smell like rotten eggs because they carry hydrogen sulfide gas. GLP-1 drugs slow how fast your stomach empties, so food sits longer and gut bacteria have more time to turn sulfur-rich food into that gas. Burping shows up in about 1 to 8 of every 100 people in the drug trials, depending on the drug and dose; it is usually worst after a dose increase and fades for most people. Smaller meals, fewer sulfur-heavy foods and slower eating are the first things to try.

This page explains where the smell comes from, how often it happens on each drug, what helps, and the symptoms that mean you should call your prescriber rather than wait it out.

What is a sulfur burp?

An ordinary burp is mostly swallowed air. A sulfur burp has the same mechanics but carries hydrogen sulfide (H₂S), the compound behind the smell of rotten eggs. Your gut bacteria make H₂S when they break down sulfur-containing protein and some sulfur compounds in food. In a controlled feeding study, the amount of sulfide in stool rose more than tenfold as meat intake went from none to 600 g a day ¹.

Most of that chemistry normally happens far down the gut, in the colon, where H₂S leaves as gas from the other end. The question on a GLP-1 drug is why it starts coming up.

Why do GLP-1 drugs cause sulfur burps?

The leading explanation is slower stomach emptying. The Zepbound label states that tirzepatide delays gastric emptying, and that the delay is largest after the first dose and shrinks over time ². The Ozempic label says the same of semaglutide ¹². The slowdown is part of how these drugs make you feel full, and it is also why the stomach and upper gut hold food longer than usual.

Longer contact time gives bacteria in the upper gut more chance to ferment protein before it moves on. A 2025 study that sampled fluid directly from the small intestine found that people with more hydrogen sulfide on a breath test had more H₂S-producing bacteria in the duodenum, the first stretch of the small intestine ³. No study has yet measured this directly in people on GLP-1 drugs, so treat the mechanism as the most plausible explanation rather than a proven one. It fits the pattern, though: symptoms cluster when the drug's effect on emptying is strongest.

How common are sulfur burps on each GLP-1 drug?

Drug labels do not separate sulfur burps from ordinary ones; they report "eructation," the medical term for burping. Here is what each current label lists from its placebo-controlled trials.

Those figures come from the Zepbound ², Wegovy ⁷, Foundayo ¹³, Mounjaro ¹¹ and Ozempic ¹² labels. The weight-loss trials tended to report more burping than the diabetes trials, which may reflect higher doses and different patients rather than a real difference between drugs.

Real-world reports point the same way. In the FDA's adverse event reporting system, eructation stood out as one of the strongest gastrointestinal signals for semaglutide ⁴, it was flagged as a new signal for tirzepatide alongside hunger and food cravings ⁵, and it was among the leading signals for oral semaglutide tablets ⁶. These databases count reports, not rates, so they show that people notice and report burping, not how often it happens.

Timing matters too. Across the semaglutide reports, most gastrointestinal events began early in treatment and became less likely over time ⁴. The Wegovy label notes that its gastrointestinal reactions were reported most often during dose escalation ⁷. If your burps started after a step up in dose, that fits the usual pattern.

Which foods make sulfur burps worse?

Because H₂S comes mainly from sulfur in food, the usual suspects are:

• •Large portions of meat, eggs and other high-protein foods, the main source of the sulfur amino acids bacteria turn into sulfide ¹.
• •Protein shakes and bars, often recommended on GLP-1s to protect muscle. Splitting them into smaller servings may help.
• •Cruciferous vegetables (broccoli, cabbage, Brussels sprouts) and onions and garlic, which carry sulfur compounds.
• •Carbonated drinks, which add gas to an already slow stomach.
• •Sugar alcohols (sorbitol, maltitol, erythritol) in "sugar-free" snacks, which ferment and add gas.

Fiber is the interesting exception. A 2023 review found that higher fiber intake may lower H₂S production even when protein intake stays high ⁸. So the goal is not to stop eating vegetables; it is to avoid big sulfur-heavy meals and pair protein with fiber.

For a fuller list of what to eat and what to go easy on while your stomach adjusts, see our gut-friendly GLP-1 food list.

What helps stop sulfur burps on a GLP-1?

Start with the simplest changes, which are the same ones prescribers use for GLP-1 nausea:

1. 1.Eat smaller meals, and stop at the first sign of fullness. Less food sitting in a slow stomach means less to ferment.
2. 2.Spread protein across the day instead of one large serving.
3. 3.Eat slowly and skip fizzy drinks, which cut swallowed air.
4. 4.Avoid lying down for a few hours after eating, especially in the evening.
5. 5.Keep a short food log for a week. Many people find one or two trigger foods.

Over-the-counter options are worth a conversation with a pharmacist rather than a guess. Bismuth subsalicylate binds hydrogen sulfide: in 10 healthy volunteers it cut the H₂S released from stool by more than 95% ⁹. That study measured gas in the colon, not burps, and the product contains a salicylate, so check with a pharmacist that it suits you and your other medications. Antacids and simethicone are commonly used for gas and heartburn, but neither has been studied for GLP-1 sulfur burps.

Do probiotics help? Possibly, for some people, and they can also make gas worse for the first week or two. Our page on bloating on GLP-1 meds covers that startup window, and probiotics on Ozempic explains which GLP-1 side effects a probiotic has evidence for. No trial has tested probiotics for sulfur burps specifically.

Should you change your dose? That is a decision for your prescriber, not something to adjust on your own. The Wegovy label, for example, tells prescribers to consider delaying the next dose increase when a dose is not tolerated ⁷, which is one reason to report burping that does not settle.

Sulfur burps with diarrhea: is it SIBO?

Many people searching for sulfur burps also have diarrhea. On breath testing, higher hydrogen sulfide levels have been linked to more severe diarrhea, urgency and abdominal pain in a nationwide study of about 3,000 people ¹⁰. That does not mean every GLP-1 user with sulfur burps has small intestinal bacterial overgrowth (SIBO), but if burping and diarrhea persist for weeks, ask your doctor whether testing makes sense. We cover the condition in SIBO and weight. Ongoing reflux alongside burping is covered in GERD and the gut microbiome.

When should you call your prescriber?

Sulfur burps on their own are unpleasant, not dangerous. Call your prescriber promptly if they come with any of the following, all of which the drug labels list as warning signs:

• •Severe or persistent abdominal pain, sometimes spreading to the back, which can signal pancreatitis ².
• •Repeated vomiting or diarrhea that keeps you from holding down fluids, because dehydration can harm the kidneys ².
• •Pain in the upper stomach, fever, yellowing of the skin or eyes, or clay-colored stools, possible signs of gallbladder problems ².
• •Stomach problems that are severe or will not go away, including burping and fullness so bad you cannot eat ².

Also tell them if symptoms are bad enough that you are thinking about stopping. There may be a slower schedule, a different dose or a different drug that suits you better.

If side effects make you rethink your program

Persistent side effects are a fair reason to revisit how your treatment is managed: how quickly your dose is increased, how easy it is to reach a clinician between refills, and whether a different medication fits. If you are comparing options, our GLP-1 telehealth ranking lists programs that show a price before the intake, and our rankings of compounded tirzepatide and compounded semaglutide programs do the same for compounded medication. For how tirzepatide may affect the gut beyond emptying speed, see tirzepatide and the gut microbiome.

The bottom line

Sulfur burps on a GLP-1 come from hydrogen sulfide made when gut bacteria ferment sulfur-rich food that is sitting longer in a slowed stomach. They are listed on every current GLP-1 label as burping, affecting a few people in every hundred in trials, and are usually worst after a dose increase. Smaller meals, less protein at one sitting, no fizzy drinks and time upright after eating are the first steps. Severe pain, repeated vomiting or signs of dehydration are reasons to call your prescriber the same day.