Functional constipation is a form of constipation with a psychological or psychosomatic background. A person suffering from it is physiologically healthy, but still experiences trouble defecating.

Functional constipation has many causes, some of which are:

• a bad diet
• an unwillingness to defecate
• nervous reactions that close the inner anal sphincter muscle, which isn't under voluntary control
• inability or unwillingness to control one's outer anal sphincter, which is normally under voluntary control
• deeper psychosomatic disorders which sometimes affect digestion and the absorption of water in the colon