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Small Bowel Bacterial Overgrowth


Small bowel bacterial overgrowth (SBBO) occurs when there is a build-up of too much bacteria in the small bowel.

The Small Intestines
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SBBO is often caused by an abnormality in the small bowel. Food is not able to flow properly though the intestines. Conditions that may cause this include:

  • Birth defect
  • Injury
  • Surgery
  • Conditions (eg, digestive disorder)

Risk Factors

Examples of conditions that may increase the risk of SBBO include:

Other risk factors include:

  • Intestinal surgery (eg, removal of part of the small intestine )
  • An obstruction in the small intestine
  • Weakened immune system
  • Being elderly (more likely to have conditions like diverticulitis)

Any condition that affects how food moves through the small bowel may increase the risk of SBBO.


Not all patients with SBBO will have symptoms. But symptoms may include:


SBBO can be difficult to diagnose. The symptoms may be similar to other conditions. Your doctor will:

  • Ask about your symptoms and medical history
  • Do a physical exam
  • Order tests, such as:
    • Blood tests to detects nutritional deficiencies (eg, anemia , B12 deficiency )
    • Breath tests—involves fasting, eating some type of sugar, and then exhaling into a bag; the sample is analyzed to find out if there are levels of certain gases
    • Culture of intestinal fluid (aspirate)—a catheter is used to get a sample of fluid from the small bowel


The goals are to:

  • Reduce the levels of harmful bacteria in the small bowel
  • Treat the underlying condition


Antibiotics are often prescribed to treat SBBO. Usually treatment is temporary. But, in some cases, you may need to take antibiotics for a longer period.

Nutritional Support

To make sure that you get the proper nutrients, you may need to:

  • Work with a dietitian
  • Follow a special diet (eg, carbohydrate-restricted diet)
  • Take supplements (eg, iron , vitamin B12 )
  • Take probiotics

In some cases, tube feeding is needed with a special formula.


For severe cases, surgery may be needed. This is done to correct an abnormality in the small bowel.


If you have any of the conditions that are linked to SBBO, get proper treatment. This may reduce your chance of having a build-up of bacteria in the small bowel.

Revision Information

  • Reviewer: Daus Mahnke, MD
  • Review Date: 09/2013 -
  • Update Date: 09/30/2013 -
  • American Gastroenterological Association


  • National Digestive Diseases Information Clearinghouse


  • Canadian Association of Gastroenterology


  • Canadian Digestive Health Foundation


  • Aaron S. Malabsorption. EBSCO Health Library website. Available at: http://www.ebscohost.com/healthLibrary/ . Updated September 20, 2010. Accessed May 12, 2011.

  • Bacterial overgrowth syndrome. Merck Manual website. Available at: http://www.merckmanuals.com/professional/sec02/ch017/ch017b.html . Updated January 2008. Accessed May 12, 2011.

  • Bures J, Cyrany J, Kohoutova D, et al. Small intestinal bacterial overgrowth syndrome. World J Gastroenterol. 2010;16(24):2978–2990.

  • Dibaise J, Young R, Vanderhoof J. Enteric microbial flora, bacterial overgrowth, and short-bowel syndrome. University of South Alabama Gastroenterology Continuing Education website. Available at: http://usagiedu.com/articles/sibo/sibo.pdf . Published 2006. Accessed May 12, 2011.

  • Lactose and glucose hydrogen breath test. Cleveland Clinic website. Available at: http://my.clevelandclinic.org/disorders/lactose%5Fintolerence/hic%5Flactose%5Fand%5Fglucose%5Fhydrogen%5Fbreath%5Ftest.aspx . Updated November 25, 2008. Accessed May 12, 2011.

  • Lin H. Small intestinal bacterial overgrowth. JAMA. 2004;292(7):852-858.

  • McCoy K. Short bowel syndrome. EBSCO Health Library website. Available at: http://www.ebscohost.com/healthLibrary/ . Updated September 20, 2010. Accessed May 12, 2011.

  • Parrish C. Nutritional consequences of small intestinal bacterial overgrowth. University of Virginia, School of Medicine website. Available at: http://www.medicine.virginia.edu/clinical/departments/medicine/divisions/digestive-health/nutrition-support-team/nutrition-articles/DiBaiseArticle.pdf . Published December 2008. Accessed May 12, 2011.

  • Small bowel bacterial overgrowth—another cause for IBS symptoms. Tennessee Society of Gastroenterology Nurses and Associates website. Available at: http://www.tsgna.org/Power.../Small%20Bowel%20Bacterial%20Overgrowth.doc . Accessed May 12, 2011.

  • Small bowel bacterial overgrowth overview. Cleveland Clinic website. Available at: http://my.clevelandclinic.org/disorders/small%5Fbowel%5Fbacterial%5Fovergrowth/dd%5Foverview.aspx . Accessed May 12, 2011.

  • Vanderhoof J, Young R. Bacterial overgrowth. The Oley Foundation website. Available at: http://www.oley.org/lifeline/bacter.html . Accessed May 12, 2011.

  • Vanderhoof J, Young R, Murray N, Kaufman SS. Treatment strategies for small bowel bacterial overgrowth in short bowel syndrome. J Pediatr Gastroenterol Nutr. 1998;27(2):155-160.