Flatus or flatulence is air or gas in the intestine that is passed through the rectum. The expulsion of air from the digestive tract through the mouth is called belching or eructation .
Gas is formed in the large intestine as a result of the action of bacteria on undigested food.
Intestinal distention from gas causes abdominal pain which may be crampy, colicky and sometimes severe. Inflammation of the intestinal wall may cause increased sensitivity to normal amounts of flatus. Even though it can cause discomfort, excessive gas is usually not a serious symptom. This list is not all inclusive, and the causes are not presented in order of likelihood. The causes of this symptom can include unlikely diseases and medications.