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.