Vomit is a mixture of stomach acid, water and undigested food that is expelled from the stomach up through the esophagus as the result of nausea. Vomiting is a typical reaction to the ingestion of certain poisons, food poisoning, dizziness, drug withdrawal and chemotherapy.
Bulimia is an eating disorder where a patient may intentionally vomit after binging. (Purging may also be done through laxatives, excessive exercise, or starvation.) A bulimic may also vomit after meals.
Occasional vomiting is normal, and is the body's first defense against poisoning. However, constant or chronic vomiting will expose the esophagus, throat and mouth to the corrosive effect of stomach acid.