Testing for Small Intestinal Bacterial Overgrowth (SIBO) requires a non-invasive 2-to-3-hour breath test. A breath test involves taking a fiber called lactulose and allowing bacteria in your small intestine to metabolize the fiber and produce gas. The bacteria produce gas, and this gas combines with your own off- gassing of carbon dioxide (CO2) in your respiration.
If you have chronic constipation you need to do a three-hour breath test. If you do not have chronic constipation, you can use a 2-hour breath test. There are three types of SIBO Hydrogen, methane, hydrogen sulfide. You want to evaluate for all possible types, if possible, when you do your breath test. Testing for just one type is not comprehensive enough to know what you are dealing with and how best to effectively treat it. Distinct types of SIBO are treated differently.