Bacteria normally exists in the intestines. It plays a role in digestion and overall health. Small intestine bacterial overgrowth (SIBO) is when there is too much bacteria in the small intestine.
The Small Intestines
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SIBO is often caused by a problem with the small intestine. Damage or defects to the intestine may slow the flow of food. The slowed food may encourage the increased growth of bacteria. Problems of the intestine may be caused by:
Any condition that affects how food moves through the intestines may increase the risk of SIBO. Some problems are:
This problem is also more common in older adults. Other risk factors are:
Problems may be:
The doctor will ask about your symptoms and health history. A physical exam will be done.
Tests may include:
Any underlying health problems will need to be treated. The goal of treatment is to lower the levels of harmful bacteria.
Antibiotics are often used to treat SIBO. Usually treatment is temporary. Some may need to take antibiotics for a longer period.
Proper nutrients can help bring back the balance of bacteria. Steps that may help are:
Some people may need tube feeding with a special formula.
Surgery may be needed for severe SIBO. It may be done to correct a problem in the small bowel.
There are no known guidelines to prevent this health problem.
American Gastroenterological Association
National Institute of Diabetes and Digestive and Kidney Diseases
Canadian Association of Gastroenterology
Canadian Digestive Health Foundation
Hydrogen breath test for lactose intolerance. Cleveland Clinic website. Available at: https://my.clevelandclinic.org/health/diagnostics/12360-hydrogen-breath-test-for-lactose-intolerance. Accessed August 20, 2021.
Short bowel syndrome. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/short-bowel-syndrome. Accessed August 20, 2021.
Small intestinal bacterial overgrowth (SIBO). Merck Manual Professional Version website. Available at: https://www.merckmanuals.com/professional/gastrointestinal-disorders/malabsorption-syndromes/small-intestinal-bacterial-overgrowth-sibo. Accessed August 20, 2021.
Last reviewed July 2021 by
EBSCO Medical Review Board
James Cornell, MD
Last Updated: 8/20/2021