A condition in which high numbers of bacteria grow in the small intestine.

In small intestinal bacterial overgrowth, the bacteria consume nutrients typically absorbed into the body by the small intestine. This may cause malnourishment. It can be caused by complications of surgery, structural problems with the intestine or certain conditions, including Crohn's disease.

Symptoms include belly bloating, pain, diarrhea and weight loss.

Treatment may include antibiotics and nutritional support, including supplements and dietary changes.