Hippocrates used the term hypochondrium in the 4th century BC to refer to the anatomic area below the ribs. Later, the term hypochondriasis emerged to refer to the ill effects upon the psyche and soma of humors or fluids that emanate from the hypochondrium and cause disease.
The Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) defines hypochondriasis as the preoccupation with fears of having, or the belief that one has, a serious disease based on misinterpretation of bodily symptoms. In hypochondriasis, this preoccupation lasts at least 6 months and persists despite appropriate medical evaluation and reassurance. Hypochondriasis causes clinically significant distress or impairment in social, occupational, or other areas of functioning. These diagnostic criteria were initially described for adults, and the same basic criteria are applied to children and adolescents.
Because the literature about hypochondriasis in children and adolescents is limited, this review includes adult studies that describe the most recent advances in the subject of hypochondriasis.
Hypochondriasis is rare in childhood and occurs more frequently in adolescence. The precise prevalence in children is unknown because of lack of epidemiologic studies.
As many as 69.2% of children in a psychiatric-based outpatient clinic reported somatic symptoms. More than 12% of adolescents and young adults reportedly have at least one somatoform condition during their lifetime. Somatoform disorder symptoms may begin in early childhood, and the full disorder generally emerges in people aged 8-12 years.
In adults, prevalence rates of hypochondriasis vary according to the population studied and the diagnostic interview used. A prevalence rate of 0.8% was described from a large sample in 15 centers worldwide, and a rate of 3% was described in a primary care adult sample.
Hypochondriasis was found in 7.7% of first-degree relatives of patients with hypochondriasis. These relatives also had a high rate of comorbid anxiety and depressive and other somatoform disorders. The relatives reported substantial physical and psychological impairment, including diminished work performance and disability. In addition, these relatives reported greater use of health care services but less satisfaction with that care. These relatives showed most of the same characteristics found in earlier studies of patients who are hypochondriacal.
In adults, prevalence rates of hypochondriasis vary according to the population studied and the diagnostic interview used. A prevalence rate of 0.8% was described from a large sample in 15 centers worldwide.
An epidemiologic German study conducted in 2007 revealed a 0.4 % prevalence rate of DSM IV hypochondriasis. 
Hypochondriasis exhibits no racial predilection.
Musculoskeletal pain is associated with depression in both girls and boys. Some data suggest that somatic symptoms are strongly associated with emotional disorders in girls and occur with increased frequency in boys with disruptive behavior disorders. For girls, musculoskeletal pain or the combination of stomachache and headache is associated with anxiety and depressive disorder. For boys, stomachache is associated with oppositional defiant disorder and with attention deficit hyperactivity disorder (ADHD). These data may reflect a degree of referral bias because more boys are referred for psychiatric evaluation for disruptive behavior disorders symptoms than are girls for their more common internalizing symptoms.
Hypochondriasis can begin in people of any age; the most common age at onset is thought to be early adulthood. The clinician should consider a diagnosis of hypochondriasis in older teenagers who have a history of prolonged preoccupation with having a serious illness.