Small bowel bacterial overgrowth


Small bowel bacterial overgrowth is a condition in which abnormally large numbers of bacteria grow in the small intestine.

Alternative Names

Overgrowth - intestinal bacteria; Bacterial overgrowth - intestine


Normally, the small intestine contains a low number of bacteria. This is different from the large intestine, which contains large numbers of bacteria.

The abnormally large numbers of bacteria in the small intestine use for their growth many of the nutrients that a person would normally absorb. As a result, a person with small bowel bacterial overgrowth may not absorb enough nutrients and will be malnourished. In addition, the breakdown of nutrients by the bacteria in the small intestines can damage the cells that line the intestinal wall. This can make it even harder for your body to absorb nutrients.

In addition, the breakdown of nutrients by the bacteria in the small intestines can damage the cells lining the intestinal wall.

Too much growth of bacteria in the small intestine can occur with many different conditions, including:


The most common symptoms are:

Other symptoms may include:

Exams and Tests


The goal is to treat the cause of the excess small intestinal bacteria growth. For certain conditions, antibiotics or drugs that speed intestinal movement (motility-speeding drugs) may be considered.

Treatment also involves getting enough fluids and nutrition.

Someone who is dehydrated may need intravenous (IV) fluids in a hospital. If the person is already malnourished, a type of nutrition given through a vein (total parenteral nutrition -- TPN) may be necessary.

Possible Complications

Severe cases lead to malnutrition. Other possible complications include:


Semrad CE. Approach to the patient with diarrhea andmalabsorption. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed.Philadelphia, PA: Saunders Elsevier; 2011:chap 142.

Review Date: 5/1/2012
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. George F. Longstreth, MD, Department of Gastroenterology, Kaiser Permanente Medical Care Program, San Diego, California. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.
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