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

• Avoid beans, cabbage, and carbonated beverages.
• Avoid gum chewing.
• Chew your food thoroughly.
• Eat more slowly.
• Relax while you eat.
• Walk for 10 - 15 minutes after eating.

Call your doctor if:

• You have other symptoms in addition to gas, like abdominal or rectal pain, heartburn, nausea, vomiting, diarrhea, constipation, or weight loss
• You have oily, foul-smelling, or bloody stools

Your doctor will perform a physical examination with special attention to your abdomen, and ask questions about your symptoms, such as:

• What is your diet like?
• Has it recently changed?
• What foods do you eat commonly?
• What foods have you eaten recently?
• Have you increased the fiber in your diet?
• How fast do you eat, chew, and swallow?
• Would you say that your gas is mild or severe?
• Does your gas seem to be related to eating milk products or other specific foods?
• What seems to make your gas better?
• What medications do you take?
• Do you have other symptoms like abdominal pain, diarrhea, early satiety (premature fullness after meals), bloating , or weight loss ?

Diagnostic tests that may be performed include:

• Abdominal CT scan
• Abdominal ultrasound
• Barium enema x-ray
• Barium swallow x-ray
• Blood studies such as CBC or blood differential
• Sigmoidoscopy
• Upper endoscopy (EGD)

Birrer RB. Irritable bowel syndrome. Dis Mon. 2002;48:105-143.

Lovelace HY, Barr SI. Diagnosis, symptoms, and calcium intakes of individuals with self-reported lactose intolerance. J Am Coll Nutr. 2005;24:51-57.

Andrès E, et al. Food-cobalamin malabsorption in the elderly. Am J Med. 2002;113:351-352.