Functional symptom

A functional symptom is a medical symptom in an individual, which has no identified cause (etiology) despite extensive diagnostic assessments. By default, a functional symptom often is judged to have causes that are neither physical nor physiological, but rather psychological or psychiatric.

An example is functional constipation, which may have psychological or psychiatric causes. However, one type of apparently functional constipation, anismus, may have a neurological (physical) basis.