Abstract
Twenty-three children and adolescents with unexplained chronic fatigue were evaluated with emphasis upon illness-onset characteristics. Ten subjects had an acute, “flu-like” onset, and four of these subjects had episodes of mild fatigue in the year prior to onset. The thirteen remaining subjects had a gradual onset of chronic fatigue, the majority describing increasing episodes of apparent infectious illnesses associated with fatigue. In these subjects, the fatigue eventually became constant, causing reduction in overall activity levels. In a comparison of subjects who did and did not meet diagnostic criteria for chronic fatigue syndrome, there were no differences in onset characteristics, but differences were noted in illness severity. The majority of children and adolescents with unexplained chronic fatigue had a gradual onset of debilitating symptoms.