Functional constipation is a type of constipation that is caused by a disruption in the normal functioning of the digestive system. It is not caused by any underlying medical condition or disease. Symptoms of functional constipation include infrequent bowel movements, hard stools, straining during bowel movements, and a feeling of incomplete evacuation. Treatment typically involves lifestyle changes such as increasing fiber and fluid intake, exercising regularly, and avoiding certain foods that can cause constipation.