Forceful or prolonged vomiting is the direct cause of Mallory-Weiss syndrome. The tear in the gastric mucosa probably occurs when the upper esophageal sphincter fails to relax during vomiting. This lack of sphincter coordination seems more common after excessive intake of alcohol. Other factors or conditions that may increase intra-abdominal pressure and predispose a person to esophageal tearing include coughing, straining during defecation, trauma, seizures, childbirth, hiatal hernia, esophagitis, gastritis, and atrophic gastric mucosa and bulimia.

Hypovolemia may develop if bleeding is excessive. Rarely, massive bleeding—usually from a tear on the gastric side near the cardia—quickly leads to fatal shock.

Typically, the history will reveal a recent bout of forceful vomiting, followed by vomiting of bright red blood or coffee-ground vomitus. The patient may describe this bleeding as mild to massive and may complain of accompanying epigastric or back pain. He may also report passing large amounts of blood rectally a few hours to several days after normal vomiting. Be alert for a history of hiatal hernia or alcoholism.