Illness anxiety disorder (IAD) was introduced in DSM-5 as a distinct diagnostic category, replacing the prior diagnosis of hypochondriasis. The DSM-5 reconceptualization recognizes that some patients with health anxiety have minimal somatic symptoms but persistent preoccupation with having or acquiring serious illness, while others (now diagnosed with somatic symptom disorder) experience significant distressing physical symptoms. IAD is characterized by preoccupation with having or acquiring a serious illness, absence of somatic symptoms or only mild symptoms (if symptoms are prominent and distressing, somatic symptom disorder is diagnosed), high level of anxiety about health, excessive health-related behaviors (checking body, researching symptoms) or maladaptive avoidance, and duration of at least 6 months.
Two specifiers are recognized: care-seeking type (frequent medical visits, multiple specialists, repeated testing) and care-avoidant type (avoiding medical care due to fear of bad news). IAD typically begins in early to middle adulthood, often after a real illness in self or loved one, exposure to illness information, or major life stressor. Risk factors include childhood illness or parental illness anxiety, anxiety or depressive disorders, traumatic medical experiences, and certain personality traits (neuroticism, perfectionism). The disorder substantially impairs quality of life, occupational functioning, relationships, and contributes to significant healthcare overutilization with associated costs and iatrogenic risks from unnecessary testing.
Effective treatment combines multiple modalities. Psychoeducation about the cycle of anxiety, body monitoring, catastrophic interpretation, reassurance-seeking, and temporary relief that maintains the cycle is fundamental. Cognitive behavioral therapy (CBT) specifically targets these elements through cognitive restructuring of catastrophic illness beliefs, behavioral experiments testing predictions, exposure exercises to feared bodily sensations or illness information, response prevention for reassurance-seeking and checking behaviors, and mindfulness-based approaches reducing reactivity to bodily sensations. Primary care management is critical: a single trusted primary care physician with regular scheduled visits (rather than as-needed visits), brief structured visits with limited testing (avoiding both excessive workup and dismissive responses), validation of distress while not validating illness fears, and coordination of mental health treatment. SSRIs (sertraline, fluoxetine, paroxetine) are effective for comorbid depression and anxiety symptoms. Treatment outcomes are improved with a collaborative care model integrating primary care and mental health services.