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This information is intended only to provide general guidance. It does not provide definitive medical advice. It is important that you consult your doctor about your specific condition.


Bloating is an uncomfortable sense of fullness in the abdomen. It can be caused by the accumulation of gas or food in the stomach or the intestine. Some people can also feel bloated when they have normal amounts of gas in the abdomen, due to abnormal sensitivity to normal amounts of gas or food or to a delay in the passage of gas or food through the stomach or intestine.

Causes of bloating

  • Excessive air swallowing (aerophagia): Aerophagia can cause excessive belching, bloating, or both. This can occur with:
    • Gulping air during meals, due to eating too fast, very animated conversations, using drinking straws, slurping liquids, or poorly fitting dentures.
    • A subconscious nervous habit.
    • Chronic postnasal drip.
    • A subconscious reaction to abdominal or chest discomfort.
  • Poor digestion of certain nutrients, such as:
    • Lactose (in dairy products)
    • Fructose (in food or high fructose corn syrup)
    • Gluten (in wheat, oats, rye)
    • Raffinose (in beans, peas, lentils, soy products)
    • Polyols (in artificial sweeteners such as xylitol and sorbitol)
    • Other vegetables (cabbage, Brussel sprouts, onions, garlic, zucchini, artichokes)

When these nutrients are not digested in the small intestine (the upper part of the intestine), they reach the colon (the large intestine), where the bacteria living in the colon act on them to form gases, which can cause bloating.

  • Small intestinal bacterial overgrowth (SIBO): Normally, the small intestine does not contain many bacteria (unlike the colon, which contains trillions of bacteria). When there is an excessive quantity of bacteria in the small intestine, you can develop bloating, flatulence (the passage of excessive amounts of gas from the rectum), or even diarrhea. Small intestinal bacterial overgrowth (SIBO) can occur when there is an abnormality of the muscular coordination and propulsion through the small bowel, after surgery, or without a known cause.
  • Dysbiosis: Normally, there are trillions of bacteria (the microbiome) with hundreds of different species, living in the colon. If certain types of the bacteria increase in number, they can cause symptoms. This is called dysbiosis.
  • Constipation: Due to the excessive accumulation of stool and excessive gas in the colon.
  • Abnormal sensation: In some people, even a normal amount of gas in the intestine produces an uncomfortable bloating sensation, because the intestine is more sensitive to degrees of distention and bloating that would otherwise not be noticed.
  • Intestinal parasites are microscopic germs (such as Giardia and cryptosporidium) or worms that can live in the intestine for months or years and cause short-term or long-lasting symptoms such as bloating.
  • Incoordination of abdominal wall muscles in the front of the abdomen, and the diaphragm and other muscles involved in breathing.
  • Obesity: Excessive fat in the abdomen can cause bloating discomfort.

More than one of these abnormalities may be present and contribute to the symptom of bloating. For example, patients with lactose intolerance, which produces excessive gas, may also have abnormal sensitivity to that gas and may also have dysbiosis, with certain types of bacteria in the colon that produce more gas from the lactose that is not digested.

How are the causes of bloating identified?

Dr. Harary, in his New York City office, will take a careful history and do a physical examination, which can help greatly in identifying the abnormalities that are causing bloating. Before you see your gastroenterologist about bloating, you should pay attention to possible dietary triggers, when the bloating occurs, and whether it is associated with constipation or other changes in her bowel movements.

Dr. Harary may order certain diagnostic tests, depending on your exact history, such as:

  • Stool tests for parasites.
  • Blood tests to evaluate possible thyroid disease or other conditions.
  • Breath tests, which are of limited accuracy but can sometimes give hints as to the cause of bloating.
  • Motility testing to measure the muscular activity, coordination, and propulsion through the gastrointestinal tract.
  • X-rays, such as an upper GI series or CT scans.

Observing your response to various treatments, including elimination diets, probiotics, antibiotics, or laxatives, can also help to determine what is causing bloating.

How is bloating treated?

Depending on the cause or causes, bloating can be treated with:

  • Eliminating suspected nutrients from the diet.
  • Medications for parasites.
  • Probiotics
  • Simethicone, which is the active ingredient in such over-the-counter medications as Gas-X, Mylicon, and Phazyme. Simethicone helps to break up large gas bubbles in the stomach.
  • Antibiotics that can eliminate small intestinal bacterial overgrowth (SIBO) or change the microbiome, the bacteria living in the colon (if there is dysbiosis). Xifaxan (rifaximin) is a new antibiotic that stays inside the intestine, where it acts, and is not absorbed into the rest of the body.
  • Treating constipation if it is present.
  • Avoiding aerophagia (excessive air swallowing) by eating slowly, chewing carefully, and becoming aware that you are doing this.
  • Medications to improve the muscular activity (motility) in the stomach or intestine.
  • Medications to normalize sensation in the GI tract.
  • Psychological treatments including cognitive behavioral therapy (CBT), hypnosis, medications, and stress reduction.
  • Miscellaneous drugs such as Beano, Lactaid, and herbal teas.

To learn more about the treatment of bloating offered by Dr. Harary, please contact our New York City office today.


Albert M. Harary, MD
110 East 55th Street, 17th Floor
Midtown East/Upper East Side

New York, NY 10022
Phone: 212-702-0123

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