Illness anxiety disorder (IAD) is a DSM-5 diagnosis replacing the older hypochondriasis category. The core feature: preoccupation with having or acquiring a serious illness without prominent somatic symptoms (minimal or no actual symptoms, in contrast to somatic symptom disorder where significant symptoms are present).
DSM-5 criteria: preoccupation with having or acquiring serious illness; somatic symptoms not present or only mild in intensity, with disproportionate fear about presence or progression; high level of anxiety about health with easy alarm about personal health status; excessive health-related behaviors (repeatedly checking body for signs of illness, researching symptoms, requesting reassurance) OR maladaptive avoidance (avoiding doctor appointments, hospitals, ill people); illness preoccupation has been present for at least 6 months but specific feared illness may change.
Two subtypes:
Care-seeking type — frequent medical visits, repeated workups, "doctor shopping," extensive consultation of health information. The pattern of seeking reassurance that briefly relieves anxiety before doubt returns.
Care-avoidant type — avoiding medical care due to fear of bad news. The patient may avoid annual exams, ignore symptoms that should be evaluated, avoid hospitals or doctors entirely. Substantial health consequences when real medical conditions are missed.
The clinical phenotype: patient interprets minor sensations (a headache, a fleeting chest tightness, a skin imperfection) as evidence of serious illness. Researches symptoms online, often with elaborate self-diagnoses. Cannot be reassured by normal test results — the worry persists or migrates to a new feared illness. Scans body repeatedly for signs of disease. Healthcare utilization either dramatically elevated (care-seeking) or paradoxically low (care-avoidant).
Distinction from somatic symptom disorder: SSD requires prominent persistent somatic symptoms; IAD does not. SSD focuses on the symptoms; IAD focuses on the fear of illness. Both involve excessive illness-related thoughts and behaviors, but the symptom dimension differs.
Comorbidities: generalized anxiety disorder, OCD (illness anxiety can have OCD-like quality with intrusive fears and reassurance-seeking compulsions), depression, panic disorder. Distinguishing primary IAD from these can be challenging when comorbid.
Treatment:
CBT specifically for health anxiety is first-line — most evidence-based intervention. Addresses cognitive distortions about health and bodily sensations, behavioral patterns (checking, reassurance-seeking, avoidance), and exposure to feared situations. Substantial effect size when patient engages.
Primary care medical home approach — same as for SSD. Regular scheduled visits, single clinician, minimize unnecessary testing, validate the distress without escalating workup.
SSRIs for severe symptoms or comorbid OCD/anxiety. Sertraline, fluoxetine, escitalopram all have evidence.
Address comorbidities with standard approaches.
The reassurance trap: a central treatment principle is that reassurance produces only transient anxiety relief and reinforces the disorder long-term. Patients describe asking for reassurance, feeling briefly relieved, then doubting again within hours. CBT addresses this by reducing reassurance-seeking and reassurance-providing behaviors — counterintuitive but evidence-based.
When you encounter a patient with preoccupation about illness disproportionate to actual symptoms or workup findings, IAD is the diagnosis. The clinical approach is structured, evidence-based, and effective. The patient's distress is real even when the feared illness is not present.