Breath Testing for Small Intestinal Bacterial Overgrowth Syndrome

Small Intestinal Bacterial Overgrowth (SIBO) is a serious digestive disturbance which can be treated effectively, but only if it is accurately diagnosed.

Typically, small amounts of bacteria are found in the small intestine. Occasionally, additional bacteria migrate from the large intestine into the small intestine, creating symptoms such as abdominal pain, bloating, gas, and diarrhea. As the symptoms are very similar to those associated with IBS (Irritable Bowel Syndrome), data from this test may assist physicians in evaluating IBS cases.

Small Intestinal Bacterial Overgrowth can easily be diagnosed by testing patients' breath samples for levels of hydrogen, methane, or both. After ingesting a substrate packet, the patient produces breath samples every 20 minutes over a 3-hour period.

Samples are then mailed to Commonwealth Laboratories LLC. Analysis of the samples yields data on production of the targeted gases as the digestive process proceeds. The graph produced using this data provides key indicators of the existence/ extent of SIBO. The graph is a clear and understandable tool that physicians may share with patients in reviewing their test results.


Unlike the large intestine, the small intestine does not have a high number of bacteria. When there are too many bacteria in the small intestine, these organisms use up the nutrients that would otherwise be absorbed into the body. A person with small bowel bacterial overgrowth may becomemalnourished as a result.

The breakdown of nutrients in the small intestine by the excess bacteria can also damage the intestinal lining. This can make it even harder for the body to absorb nutrients.

Conditions that can lead to overgrowth of bacteria in the small intestine include:

  • Complications of diseases or surgery that create pouches or blockages in the small intestine.Crohn's disease is one of these conditions.
  • Diseases that lead to movement problems in the small bowel, such as diabetes andscleroderma
  • Immunodeficiency such as AIDS or immunoglobulin deficiency
  • Short bowel syndrome caused by surgical removal of part of the small intestine
  • Small bowel diverticulosis, in which small sacs occur in the inner lining of the intestine. These sacs allow too many bacteria to grow. These sacs can occur anywhere along the intestinal tract, but they are much more common in the large bowel.
  • Surgical procedures that create a loop of small intestine where excess bacteria can grow. An example is a Billroth II type of stomach removal (gastrectomy).
  • Some cases of irritable bowel syndrome (IBS)


The most common symptoms are:

  • Abdominal fullness
  • Abdominal pain and cramps
  • Bloating
  • Diarrhea (usually watery)
  • Gassiness

Other symptoms may include:

  • Fatty stool
  • Weight loss

How to prepare for the SIBO Breath Testing?

There is a 24-hour preparation period before taking the test; the first 12 hours require a specific diet, and the last 12 hours require a complete fasting period; however, you may brush your teeth.

Can small intestinal bacterial overgrowth be treated?

Yes. Once bacterial overgrowth has been diagnosed, a health practitioner can use an appropriate antibiotic regimen to eradicate the bacteria, relieving the symptoms. Treatment can then begin on the underlying causes to keep overgrowth from recurring.

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