Drug facts

Heartburn, acid reflux and burping on tirzepatide

By David Chen·Editor·Reviewed September 2026

The rows in the label¹

Table 1 pools the two placebo-controlled obesity trials, Study 1 and Study 2, and lists every reaction reported by at least 2% of participants on Zepbound and more often than on placebo. Five of its rows are about the upper gut or gas:

These are single-digit reactions. Indigestion is the largest, about five points above placebo at every dose; reflux and belching sit two to four points above it. For scale, nausea in the same table runs 25–29%. Only the first three reach 5% at any dose, the cut-off the label’s highlights use for its list of most common reactions. The full table →

What the label calls it²

The prescribing information is written for clinicians. The Medication Guide, approved alongside it for patients, lists the same twelve most common side effects in plainer words. Matched up, the three terms on this page become:

Dyspepsia

“indigestion”

Eructation

“belching”

Gastroesophageal reflux disease

“heartburn”

So if you are searching for acid reflux, heartburn, indigestion or burping on Zepbound or Mounjaro, these three rows are the label’s answer. It does not break any of them down further.

“Sulfur burps” are not on the label³

The phrase is a lay description of belching with a foul, eggy smell or taste. The label has no such entry. It counts eructation, with no description of what it is like, and the word “sulfur” does not appear anywhere in the prescribing information or the Medication Guide.

Explanations of why it happens circulate widely, and none of them comes from the label. The one relevant thing the label does state is in its own words: tirzepatide delays gastric emptying, with the delay “largest after the first dose” and diminishing over time. It gives that as the reason the drug can change how oral medicines are absorbed, including oral contraceptives. It does not connect it to belching or to reflux, and this page does not either. What delayed emptying means for other medicines →

When it is not heartburn⁴

Upper-stomach discomfort has more serious neighbors on the same label. These are not rated by frequency here, because a percentage is the wrong tool for them.

Acute pancreatitis (5.5)

The label describes its signs as “persistent or severe abdominal pain (sometimes radiating to the back) and which may or may not be accompanied by nausea or vomiting,” and says to stop the drug if pancreatitis is suspected.

Acute gallbladder disease (5.4)

The Medication Guide lists pain in the upper stomach, fever, yellowing of the skin or eyes, and clay-colored stools.

Severe gastrointestinal reactions (5.2)

Reported more often on the drug than on placebo; the label says it is not recommended in people with severe gastroparesis.

Anesthesia and sedation (5.9)

Rare postmarketing reports, in people on GLP-1 receptor agonists, of pulmonary aspiration under general anesthesia or deep sedation, with food still in the stomach despite reported fasting. What the label says before surgery.

What the Mounjaro label reports⁵

Mounjaro’s label draws on adults with type 2 diabetes and uses a 5% cut-off for its table, so fewer of these reach it. Dyspepsia is in Table 1 at 8%, 8% and 5% at 5, 10 and 15 mg against 3% on placebo. Eructation and reflux appear in the text instead, as gastrointestinal reactions reported more often than on placebo: eructation at 3.0%, 2.5% and 3.3% against 0.4%, and reflux at 1.7%, 2.5% and 1.7% against 0.4%. Different trials and a different population, so the two labels’ figures are not interchangeable.

What none of this covers

Nothing here is medical advice, and this page deliberately suggests no remedy, food change or antacid. Whether a symptom needs treating, and how, is a question for the prescriber. See the medical disclaimer. The other common gut reactions have their own pages: diarrhea and constipation.