Gas, also called flatus or flatulence, is air in the intestine that is passed through the rectum. Air that is passed from the digestive tract through the mouth is called belching.

Gas is formed in the intestines as food is being digested. Gas can make you feel bloated, which may cause crampy or colicky abdominal pain.

Gas can be caused by any of the following:

• Antibiotics
• Eating foods that are difficult to digest, such as fiber. If you recently introduced fiber into your diet, having gas may be temporary. Give it a little time. Your body may adjust and stop producing gas.
• Eating foods that you cannot tolerate -- for example, if you have lactose intolerance and eat dairy products
• Irritable bowel syndrome -- a chronic form of stomach upset that gets worse with stress
• Malabsorption (when your body cannot absorb or digest a particular nutrient properly, often accompanied by diarrhea)
• Swallowing air while eating