Quick answer: Mounjaro sulfur burps are a form of burping (eructation), a listed side effect of tirzepatide. In the Mounjaro diabetes trials, burping affected 2.5% to 3.3% of people versus 0.4% on placebo, and in the Zepbound weight-loss trials 4% to 5% versus 1%.[1][2] It is linked to tirzepatide’s effect of slowing how fast the stomach empties, which is strongest after the first dose and fades over time.[1][3]
The labels list burping but do not describe the smell. “Sulfur burps” is the term patients use for burps that smell like rotten eggs. For general background on the drug, see our tirzepatide profile.
How common is burping on Mounjaro and Zepbound?
Mounjaro (type 2 diabetes trials):[1]
| Side effect | Placebo | 5 mg | 10 mg | 15 mg |
|---|---|---|---|---|
| Burping (eructation) | 0.4% | 3.0% | 2.5% | 3.3% |
| Indigestion (dyspepsia) | 3% | 8% | 8% | 5% |
| Gas (flatulence) | 0% | 1.3% | 2.5% | 2.9% |
| Acid reflux (GERD) | 0.4% | 1.7% | 2.5% | 1.7% |
| Bloating (abdominal distension) | 0.4% | 0.4% | 2.9% | 0.8% |
Zepbound (weight-management trials):[2]
| Side effect | Placebo | 5 mg | 10 mg | 15 mg |
|---|---|---|---|---|
| Burping (eructation) | 1% | 4% | 5% | 5% |
| Indigestion (dyspepsia) | 4% | 9% | 9% | 10% |
| Acid reflux (GERD) | 2% | 4% | 4% | 5% |
| Gas (flatulence) | 2% | 3% | 3% | 4% |
| Bloating (abdominal distension) | 2% | 3% | 3% | 4% |
Burping is far less common than nausea. In the Zepbound trials, nausea affected 25% to 29% of people on tirzepatide.[2] Burping also shows up in real-world reports: a 2026 analysis of more than 123,000 reports to the FDA’s adverse event database found eructation reported more often than expected with tirzepatide.[4]
Why tirzepatide causes burping
Tirzepatide slows gastric emptying, the speed at which food leaves the stomach for the intestine.[1]
- The effect is strongest at the start. In early studies, a single dose of tirzepatide delayed stomach emptying, and the effect became smaller with repeated doses.[3] The labels say the delay is largest after the first dose and diminishes over time.[1][2]
- It returns briefly with dose increases. In people with type 2 diabetes whose dose was being raised, some delay was still seen after several doses.[3]
- Food sits longer. When the stomach empties slowly, people feel full sooner, and gas and pressure can build. Burping releases that gas.
Why the sulfur smell? The labels do not explain it. A commonly offered explanation is that food staying in the gut longer gives more time for sulfur-containing gases, such as hydrogen sulfide, to form during digestion. This idea is plausible but has not been tested directly in tirzepatide studies.
When sulfur burps are most likely
Based on how the gut side effects behave in trials:
- After starting and after each dose increase. In the Zepbound trials, most nausea, vomiting and diarrhea happened during dose escalation and decreased over time.[2] Mounjaro trials showed the same pattern.[1]
- After large or rich meals. A slower stomach has more to deal with after a big meal.
- At higher doses. Burping rates were higher on tirzepatide than placebo at every dose, with the Zepbound figures slightly higher at 10 and 15 mg.[2]
See the tirzepatide dosage chart for when dose steps happen.
What can help
There are no clinical trials testing remedies for tirzepatide-related burping. The steps below are practical measures that follow from how the drug works. Check with your prescriber or pharmacist before adding any medicine.
- Eat smaller meals, more slowly, and stop when you first feel full.
- Go easy on fatty, fried and very rich foods, which already take longer to leave the stomach.
- Notice your own triggers. Some people find that eggs, red meat, cruciferous vegetables (broccoli, cabbage, cauliflower) or carbonated drinks make burps worse.
- Avoid lying down right after eating, which can make reflux worse.
- Limit alcohol, which can worsen reflux and nausea. See our guide on GLP-1 drugs and alcohol.
- Stay hydrated, sipping water through the day rather than gulping large amounts with meals.
- Ask about slowing the dose schedule. The labels set a minimum of 4 weeks per dose step, not a maximum, and they allow a lower maintenance dose if a higher one is not tolerated.[2]
- Ask a pharmacist about over-the-counter options for gas or reflux, and check whether they interact with your other medicines.
Tirzepatide can change how well other oral medicines are absorbed, so mention anything new you start.[1]
Burping, reflux and indigestion: how they overlap
Burping often comes with other upper-gut symptoms. On Zepbound, indigestion affected 9% to 10% of people and acid reflux 4% to 5%, both higher than placebo.[2] If burping comes with a burning feeling in the chest or a sour taste, reflux may be part of the picture, and the measures above, especially smaller meals and not lying down after eating, may help both. Persistent reflux symptoms are worth raising with your prescriber, since they can have other causes.
When to call a doctor
Burping on its own is usually mild. Get medical advice promptly if it comes with:
- Severe or persistent belly pain, sometimes spreading to the back, with or without vomiting. This can be a sign of pancreatitis.[2]
- Pain in the upper right belly, fever or yellow skin or eyes, which can signal gallbladder problems. Gallbladder inflammation was reported in 0.7% of people on Zepbound versus 0.2% on placebo.[2]
- Repeated vomiting or diarrhea with dizziness or little urine, which can lead to dehydration and kidney injury.[2]
- Severe gut symptoms. Severe gastrointestinal reactions were reported in 1.7% to 3.1% of people on Zepbound versus 1% on placebo, and Zepbound is not recommended for people with severe gastroparesis.[2]
Sulfur burps vs other stomach side effects
Burping is one of several gut effects of tirzepatide. In the Zepbound trials, 56% of people on any dose had at least one gastrointestinal side effect, versus 30% on placebo, and 1.9% to 4.3% stopped treatment because of them.[2] For skin-related side effects, see Mounjaro skin sensitivity. For how the two brands differ, see Zepbound vs Mounjaro.
