Small Intestinal Bacterial Overgrowth (SIBO)

  • Medical Author:
    Benjamin Wedro, MD, FACEP, FAAEM

    Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.

  • Medical Editor: Bhupinder S. Anand, MBBS, MD, DPHIL (OXON)
    Bhupinder S. Anand, MBBS, MD, DPHIL (OXON)

    Bhupinder S. Anand, MBBS, MD, DPHIL (OXON)

    Dr. Anand received MBBS degree from Medical College Amritsar, University of Punjab. He completed his Internal Medicine residency at the Postgraduate Institute of medical Education and Research, Chandigarh, India. He was trained in the field of Gastroenterology and obtained the DPhil degree. Dr. Anand is board-certified in Internal Medicine and Gastroenterology.

Small intestinal bacterial overgrowth (SIBO) facts

  • Small intestine bacterial overgrowth is often associated with other underlying illnesses.
  • Symptoms involving the intestine are non-specific in the early stages and include indigestion, diarrhea, abdominal pain, and bloating.
  • As the disease progresses, the inability of the body to absorb nutrients from the intestine may lead to malnutrition and vitamin deficiencies that may help direct testing to find the diagnosis.
  • The diagnosis is often one of exclusion, making certain that other malabsorption syndromes also are not present.
  • Blood tests, breath tests, and biopsies or tissue samples from the small intestine may be required to make the diagnosis.
  • Antibiotics may be prescribed but the type and length of treatment depends upon the patient and the symptoms.
  • Any underlying illness will also need to be addressed at the same time once therapy is started for SIBO.
  • The prognosis depends upon how well the associated illnesses are managed. Relapse is fairly common.

What causes SIBO?

The small intestine is a relatively clean place. The stomach receives food, mixes it with acid and digestive juices and turns it into a clean slurry that is pushed through the three parts of small intestine (duodenum, jejunum, ileum) where the nutrients are absorbed into the body. The refuse is dumped into the large intestine, or colon, where water is absorbed and the feces become more solid and are eliminated from the body.

The normal bacteria (flora) of the gut, perform important functions, helping to digest certain vitamins like folic acid and vitamin K, and they protect the intestine from being invaded by disease causing bacteria. However, if the normal function of the intestine is compromised, bacterial overgrowth may occur. This may be the result of a lack of adequate stomach acid, damage to the intestine by toxins like alcohol, or a decrease in the speed at which the small intestine transfers material to the colon.

The colon is not as clean as the small intestine and reflux, or backflow, of stool into the small intestine can colonize it with harmful bacteria.

Medically Reviewed by a Doctor on 3/16/2016

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