Illness Anxiety Disorder is an anxiety-based psychiatric condition characterized by the individual’s persistent and excessive fear of having or developing a serious medical illness. The most prominent feature of this disorder is that, despite the absence of an actual disease, the individual misinterprets bodily sensations and continuously experiences a sense of health-related threat. Classified under Somatic Symptom and Related Disorders in DSM-5, this condition represents a reconceptualization of what was previously known as “hypochondriasis.” Illness Anxiety Disorder typically begins in the 20s or 30s and may follow a chronic course.

The disorder can affect not only the individual’s relationship with the health care system but also multiple domains of daily functioning. Decreased functionality, excessive medical consultations, strained social relationships and reduced quality of life are frequently observed. Patients often seek repeated diagnostic testing from various specialists, yet their anxiety persists even when test results are normal.

DSM-5 Criteria for Illness Anxiety Disorder

According to DSM-5, the following criteria must be met for a diagnosis of Illness Anxiety Disorder:

• Preoccupation with having or acquiring a serious illness.
• Somatic symptoms are absent or only mild in intensity. However, the individual’s health-related concern is disproportionate.
• The health anxiety is associated with a high level of anxiety, leading to excessive health-related behaviors (e.g., frequent medical visits) or maladaptive avoidance (e.g., avoiding doctors and hospitals).
• The illness-related preoccupation has lasted for at least six months, although the specific feared illness may change over that time.
• The condition is not better explained by another mental disorder (such as Somatic Symptom Disorder, Obsessive-Compulsive Disorder or Major Depressive Disorder).

DSM-5 further divides this disorder into two subtypes:

• Care-seeking type: Characterized by frequent medical visits and repeated diagnostic testing.
• Care-avoidant type: Characterized by avoidance of doctors and medical environments due to fear of being diagnosed with an illness.

Illness Anxiety Disorder Symptoms

Individuals with Illness Anxiety Disorder may exhibit the following symptoms:

• Interpreting normal bodily sensations as signs of serious illness (e.g., perceiving normal heartbeats as cancer symptoms)
• Distrust of medical test results
• Excessive internet searches about medical conditions (cyberchondria)
• Failure to be reassured by family or physicians
• Persistent thoughts of illness acquisition
• Severe anxiety without observable physical symptoms
• Daily life revolving around health-related concerns

These symptoms impair both internal well-being and social-occupational adaptation, often leading to psychological distress and depressive symptoms.

Etiology of Illness Anxiety Disorder

The development of Illness Anxiety Disorder is understood through a biopsychosocial model, where biological predispositions, learned psychological processes and environmental influences interact.

1. Genetic and Neurobiological Factors

• More prevalent in individuals with a family history of anxiety disorders or somatic symptom disorders.
• Dysregulation in serotonin and norepinephrine systems may impair anxiety regulation and contribute to the disorder.
• Functional neuroimaging studies have demonstrated increased activation in the anterior cingulate cortex and insula in affected individuals (Starcevic, 2014; Barsky & Ahern, 2004).

2. Learned Behaviors and Cognitive Biases

• Exposure to parental models excessively focused on illness during childhood
• History of serious illness in early life or witnessing severe illness in close relatives
• Maladaptive automatic thoughts (e.g., “If I have chest pain, I must be having a heart attack”) and selective attention mechanisms that amplify bodily sensations

3. Cultural and Social Factors

• High exposure to illness-related information in the media
• Frequent use of medical terminology in everyday contexts
• Easy access to health services, reinforcing repeated medical consultations

Risk Factors for Illness Anxiety Disorder

• History of anxiety or depression
• Recent illnesses or medical events
• Traumatic life experiences (e.g., parental loss, abuse)
• Parental health anxiety models
• Unclear or insufficiently reassuring communication from physicians

Recognition of risk factors is critical, particularly in primary care, for early identification and intervention.

Diagnosis of Illness Anxiety Disorder

Diagnosis requires a detailed clinical interview by a psychiatrist or clinical psychologist, based on DSM-5 criteria. Key considerations include:

• Severity of health-related anxiety
• Presence or absence of bodily symptoms
• Degree of impairment in daily functioning
• Relationship with the health care system (excessive consultation or avoidance)
• Differential diagnosis to exclude Somatic Symptom Disorder, Generalized Anxiety Disorder, Obsessive-Compulsive Disorder and Major Depressive Disorder

If an organic condition is suspected, limited medical evaluations may be conducted, but repeated unnecessary testing should be avoided.

Treatment of Illness Anxiety Disorder

Illness Anxiety Disorder is highly treatable with individualized and multimodal interventions.

1. Psychotherapy

Cognitive Behavioral Therapy (CBT) is considered the first-line treatment. Clinical studies demonstrate that CBT reduces health anxiety and decreases reassurance-seeking behaviors (Hedman et al., 2016).

Within CBT:

• Misinterpretations of bodily sensations are examined
• Cognitive distortions are corrected
• Skills for coping with avoidance and excessive checking behaviors are developed
• Exposure and response prevention (ERP) techniques may be implemented

2. Pharmacotherapy

Selective serotonin reuptake inhibitors (SSRIs) are effective in reducing anxiety symptoms and are commonly recommended as a first-line pharmacological option. Pharmacotherapy may be particularly beneficial when depressive symptoms coexist with anxiety.

Research indicates that a combination of medication and psychotherapy produces greater clinical improvement than either treatment alone, supporting an integrated approach to care.

3. Psychoeducation

Patients are provided accurate information about the disorder, its course and treatment options. Involving family members prevents reinforcement of reassurance-seeking or avoidance behaviors.

Impact on Daily Life

Individuals with Illness Anxiety Disorder may experience significant functional impairment due to persistent health-related worries:

• Reduced productivity in occupational settings
• Weakened social relationships
• Restriction of daily activities (e.g., avoiding exercise)
• Disturbed sleep and eating patterns
• Economic burden due to excessive medical testing

Over time, depressive symptoms and social isolation may develop. If untreated, the disorder can substantially lower quality of life.

Illness Anxiety Disorder highlights the complexity of the mind-body connection. Although common, it is often underdiagnosed. Early recognition and appropriate intervention can markedly improve outcomes. Psychoeducation, CBT and, when necessary, pharmacotherapy represent effective long-term treatment strategies. Sensitization of health care professionals to this condition has the potential to improve both patient well-being and system-level efficiency.