The small intestinal malcolonization (SIBO) is usually diagnosed by means of a breath test. The affected person drinks a special sugar solution (usually glucose or lactulose), whereupon the concentration of hydrogen and methane in the exhaled air is measured at regular intervals. A rapid increase in these gases indicates a bacterial overgrowth. In addition, blood tests, stool examinations and imaging procedures can be carried out to rule out other causes. Early diagnosis is important in order to treat SIBO effectively.