Small intestinal bacterial overgrowth (SIBO) is an often overlooked digestive disorder that can cause a variety of symptoms. It occurs when bacteria that normally live in the large intestine colonize excessively in the small intestine. This incorrect colonization leads to digestive disorders, impairs the absorption of nutrients and can significantly reduce quality of life. In this article, we look at the causes, symptoms, diagnosis and treatment options for small intestinal bacterial overgrowth (SIBO).