The short answer
Sulfur burps are hydrogen sulfide, a gas bacteria make when they break down the sulfur in protein. A GLP-1 slows your stomach, so eggs, meat, dairy and shakes sit longer and ferment before they move on, and the gas comes back up. It is common in the first weeks and after dose steps, and usually settles as the gut adapts.
Rotten-egg burps are the side effect people are most embarrassed to ask about. At GLP-1 SOS we hear it every week, so here it is, plainly.
For a few days
Swap the highest-sulfur foods
Higher in sulfur
- Eggs
- Red meat and chicken
- Cheese and milk
- Whey protein shakes
- Broccoli, cabbage, cauliflower, Brussels sprouts
- Garlic and onion
Lower in sulfur
- Fish
- Tofu
- Greek yogurt in small portions
- Rice, oats, potatoes
- Cooked vegetables outside the cabbage family
- Bananas
Same daily protein, smaller portions, and bring the eggs and red meat back gradually once the burps ease.
What is actually happening
Burping is gas leaving the stomach. Most burps are swallowed air and have no smell. A sulfur burp smells of rotten eggs because it carries hydrogen sulfide, which gut bacteria produce when they break down two sulfur-containing amino acids, cysteine and methionine, and sulfate from food. The richest sources are exactly the foods people lean on when appetite is low: eggs, red meat, chicken, cheese, milk, whey protein, plus cruciferous vegetables such as broccoli and cabbage, and garlic and onion.
A GLP-1 medication slows how fast your stomach empties. The prescribing information for Ozempic, Wegovy, Mounjaro and Zepbound all state this, and burping is listed among the reactions in their trials: about 7 percent of adults on Wegovy, compared with under 1 percent on placebo, and 4 to 5 percent on Zepbound. Food that would have left the stomach in an hour or two now sits for much longer. Bacteria get time to work on the protein, the gas builds in a stomach that is not emptying, and it comes up.
Two things make it worse. Large protein loads in one sitting, because there is more raw material sitting longer. And the days after the shot, when the medication level peaks, because the stomach is at its slowest then. If your worst burps are always two or three days after injection, that is the curve.
Lab note
The medication is not creating the gas. It is changing the schedule.
The medication is not creating the gas. It is changing the schedule so more of it forms upstream, where you notice it.
How the burp forms
From plate to burp, in three steps
1
Protein sits longer
A GLP-1 slows the stomach, so eggs, meat, dairy and shakes stay there for hours instead of one.
2
Bacteria make the gas
They break down the sulfur in protein into hydrogen sulfide, the rotten-egg gas.
3
The gas comes up
It builds in a stomach that is not emptying, and leaves the only way it can.
What to do
- Split the protein. Same daily amount, smaller portions: something every three to four hours instead of one large protein-heavy meal. Less sitting in the stomach at once means less fermenting.
- For a few days, swap the highest-sulfur foods for lower ones. Fish, tofu, Greek yogurt in small portions, and cooked vegetables other than the cabbage family. Return the eggs and red meat gradually once the burps ease.
- Drink between meals, not with them. Liquid poured onto a full slow stomach adds volume and stirs the gas. Sip small amounts through the day instead.
- Skip carbonated drinks and gum for now. Bubbles and swallowed air add to the same stomach that is already holding gas.
- Stay upright for an hour after eating, and take a ten-minute walk after dinner. Gravity and movement both help the stomach empty.
- Ginger and peppermint after meals. Both have a long history with a slow, queasy stomach, which is why we put ginger root and peppermint, with a 19-strain probiotic blend, in GLP-1 SOS Daily Gut Relief.* A cup of ginger tea after dinner does part of the same job.
- Plan the shot week. Keep meals smallest on the two days after your injection and after the first higher shot of each dose step. If the burps do not fade within a couple of weeks of a dose increase, staying longer on the lower dose is a normal thing to ask your prescriber for.
*GLP-1 SOS Daily Gut Relief supports regular bowel movements and digestive comfort. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.
What the trials show
How common, and when
7%
of adults on Wegovy reported burping, compared with under 1% on placebo
4 to 5%
on Zepbound
Day 2 to 3
after the shot: when the medication peaks and the stomach is slowest
Sources: Wegovy and Zepbound prescribing information.
When to call your doctor
Call your prescriber the same day if:
- The burps come with pain
- You are vomiting
- You cannot keep liquids down
- You feel faint when you stand
- Your belly stays swollen and hard
- You go more than five days without a bowel movement
- Sulfur burps come with diarrhea lasting more than two days, fever, or weight dropping faster than you and your prescriber planned
Burps are a smell. Burps with pain are a call.
From the people behind the Lab
You do not have to figure this out alone.
GLP-1 SOS is the daily companion made for life on a GLP-1. Plain answers like this one, a support team that replies to real questions from real people, and daily formulas designed around the side effects that come with the medication. The GLP-1 Lab is our free education arm: no login, no paywall, no hype. Side effects are part of the road. Suffering through them is not.
Questions people also ask
Why do GLP-1 burps smell like eggs?
Because the gas is the same one that gives eggs their smell: hydrogen sulfide. Bacteria make it from the sulfur in protein. Eggs, meat, dairy and whey are high in it, and they sit longer in a slowed stomach, so more gas forms before the food moves on.
Do sulfur burps mean the GLP-1 is working?
They mean the stomach is emptying slowly, which is part of how the medication works. They are not a sign of a stronger effect on appetite or weight, and people with no burps are getting the same benefit. Fewer burps is a goal, not a loss.
How long do sulfur burps last on a GLP-1?
Usually they cluster in the first weeks and for a week or two after each dose increase, then ease as the gut adapts. Burps that persist for weeks at a stable dose usually track back to portion size and protein sources, which is where the fixes above start (with diarrhea or vomiting too, see sulfur burps with diarrhea or vomiting).
Does a protein shake cause sulfur burps on a GLP-1?
Often, yes. Whey is high in sulfur amino acids, and a large shake is a lot of protein landing at once in a stomach that empties slowly. Treat a shake as a meal, not a drink: smaller, slower, and not stacked on top of a meal.
Sources (6)
- Wegovy (semaglutide) injection, Prescribing Information. Novo Nordisk / FDA, revised June 2026.
- Zepbound (tirzepatide) injection, Prescribing Information. Eli Lilly, revised August 2026.
- Mounjaro (tirzepatide) injection, Prescribing Information. Eli Lilly, revised August 2026.
- Production of hydrogen sulfide by the intestinal microbiota and epithelial cells and consequences for the colonic and rectal mucosa. American Journal of Physiology: Gastrointestinal and Liver Physiology, 2021.
- The Capacity to Produce Hydrogen Sulfide (H2S) via Cysteine Degradation Is Ubiquitous in the Human Gut Microbiome. Frontiers in Microbiology, 2021.
- Clinical Recommendations to Manage Gastrointestinal Adverse Events in Patients Treated with GLP-1 Receptor Agonists: A Multidisciplinary Expert Consensus. Journal of Clinical Medicine, 2023.
Reviewed by the GLP-1 SOS editorial team · Education, not medical advice · Talk to your prescriber about your dose and your symptoms.
