Browse range of SIBO Tests available: 


  • Is the preferred substrate as it is not absorbed by humans and takes up to 2 hours to traverse the small intestine. This gives us a picture of what is happening throughout the entire small Intestine, as well as upon arrival in the colon.
  • Only bacteria, not humans, produce the enzymes to digest lactulose. Therefore, if there is a bacterial overgrowth, increases of Hydrogen and/or Methane gas after consumption of lactulose are indicative of SIBO.
  • Is recommended unless the patient has a true milk allergy (eg severe reaction from minute amounts/anaphylaxis), as there is a miniscule amount of lactose in lactulose. In this case a glucose challenge test is indicated.
  • Patients who experience Distal SIBO symptoms, ie pain in the right lower abdomen are recommended to do a Lactulose (rather than glucose) test.


  • Is highly specific for Proximal SIBO because of its rapid absorption in the first part of the small intestine.
  • Symptoms that occur within an hour of eating are suggestive of proximal SIBO, especially after consuming refined carbohydrates, sucrose, fructose and lactose. However, other nutrients such as some fats and/or protein may also trigger this response.
  • Both humans and bacteria absorb glucose. This happens in the upper part of the small intestine, which (in a healthy gut) is close to sterile, therefore if Hydrogen and/or Methane gas are produced during this test, it reflects bacterial activity – the degree and type of overgrowth is reflected in the amount and type of gas produced.
  • Because of its rapid absorption in the proximal small intestine, it fails to identify distal SIBO.
    If glucose testing is negative, a lactulose test is recommended to test for distal SIBO.

Sample Report (SIBO Lactulose)

Sample Report (SIBO Glucose)

FxMed’s SIBO Solution Booklet – Available on request from our Customer Services Team

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