Somatic Symptom and Illness Anxiety Disorders: Diagnosis and Management
The DSM-5 shift to positive psychological criteria, and a collaborative-care approach to health anxiety
DSM-5 rewrote the somatoform disorders around a simple but consequential principle: a psychiatric diagnosis should rest on what is present in the patient's thoughts, feelings, and behavior—not on the absence of a medical explanation. Somatic symptom disorder (SSD) and illness anxiety disorder (IAD) replaced hypochondriasis and somatization disorder with positive criteria centered on disproportionate health-related distress. This shift lets clinicians make the diagnosis alongside genuine medical illness, and it reframes treatment around function and the therapeutic relationship rather than a fruitless search to prove symptoms are "unexplained."
1. Nosological Reconceptualization
From "Medically Unexplained" to Positive Criteria
The DSM-IV somatoform disorders required that symptoms be medically unexplained—a criterion that was unreliable, adversarial, and mind-body dualistic, effectively telling patients their suffering was not real. DSM-5 abandoned this requirement. In SSD, the somatic symptoms may or may not be explained by a medical condition; what defines the disorder is the presence of excessive and disproportionate thoughts, feelings, and behaviors about those symptoms. A patient with documented cardiac disease can have SSD if their health-related preoccupation is clearly out of proportion.
Former hypochondriasis was split. Patients with prominent somatic symptoms plus health preoccupation now fall under SSD (roughly three-quarters of former hypochondriasis cases), while those preoccupied with the idea of having or acquiring a serious illness but with minimal actual somatic symptoms are captured by the new diagnosis of illness anxiety disorder (roughly one-quarter). The broader "somatic symptom and related disorders" chapter also houses functional neurological (conversion) disorder, psychological factors affecting other medical conditions, and factitious disorder.
2. Diagnostic Criteria and Differential Diagnosis
Somatic Symptom Disorder (DSM-5-TR)
- A. One or more somatic symptoms that are distressing or result in significant disruption of daily life.
- B. Excessive thoughts, feelings, or behaviors related to the symptoms or associated health concerns, shown by at least one of: (1) disproportionate and persistent thoughts about the seriousness of symptoms; (2) persistently high anxiety about health or symptoms; (3) excessive time and energy devoted to symptoms or health concerns.
- C. Although any one symptom may not be continuously present, the symptomatic state is persistent (typically >6 months).
- Specify: with predominant pain; persistent; and severity (mild = one Criterion B symptom; moderate = two or more; severe = two or more plus multiple somatic complaints or one very severe symptom).
Illness Anxiety Disorder (DSM-5-TR)
- A. Preoccupation with having or acquiring a serious illness.
- B. Somatic symptoms are not present or are mild; if another medical condition or high risk is present, the preoccupation is clearly excessive or disproportionate.
- C. High level of anxiety about health; the person is easily alarmed about personal health status.
- D. Excessive health-related behaviors (e.g., repeatedly checking the body, seeking reassurance) or maladaptive avoidance (avoiding doctors and hospitals).
- E. Illness preoccupation for at least 6 months, though the specific feared illness may change.
- F. Not better explained by another mental disorder.
- Specify: care-seeking type or care-avoidant type.
Epidemiology
SSD affects an estimated 5–7% of the general adult population and is even more common in primary care and specialty medical settings. Clinically significant health anxiety (the IAD construct) is reported in roughly 1–10% depending on setting and threshold. Both show a modest female predominance and frequently begin by early-to-middle adulthood, often waxing and waning across the lifespan.
Differential Diagnosis
| Condition | Core feature | Distinguishing point |
|---|---|---|
| Generalized anxiety disorder | Worry across many domains | Health is one of many worries, not the exclusive focus |
| Panic disorder | Acute somatic surges + catastrophic interpretation | Fear is of the panic attack itself, episodic and acute |
| OCD | Intrusive obsessions + compulsions | In IAD the preoccupation is ego-syntonic and disease-specific; contamination/illness OCD involves ritualized neutralizing |
| Major depressive disorder | Somatic complaints during a mood episode | Somatic focus is mood-congruent and episode-limited |
| Functional neurological (conversion) disorder | Neurological deficits incompatible with disease | Positive clinical signs of functional etiology; the deficit, not worry, is central |
| Delusional disorder, somatic type | Fixed false belief of illness/infestation | Conviction is delusional and unshakeable; in SSD/IAD reality-testing is retained |
| Factitious disorder / malingering | Feigned or induced symptoms | Intentional deception (internal vs external incentive); SSD/IAD symptoms are not consciously produced |
3. Management: The Therapeutic Relationship as Treatment
Structuring Care
The evidence base and clinical consensus converge on a stance that begins in the medical relationship itself, ideally with a single coordinating clinician:
Principles of Collaborative Care
- Regular, brief, scheduled visits not contingent on new symptoms—decoupling access to the clinician from the production of symptoms.
- Validate the symptoms as real and the distress as genuine; avoid "there's nothing wrong" and mind-body dualism.
- Minimize unnecessary testing, referrals, and procedures, which reinforce illness behavior and carry iatrogenic risk; perform a reasonable baseline workup, then shift the frame.
- Reframe the goal from cure to function—improving daily activity, work, relationships, and quality of life rather than eliminating every sensation.
- Limit repeated reassurance in IAD: reassurance relieves anxiety transiently but maintains the checking-and-seeking cycle over the long term.
- Screen and treat comorbid depression and anxiety, which are common and worsen outcomes.
Psychotherapy
Cognitive-behavioral therapy is the best-supported treatment for both SSD and health anxiety, with meta-analytic evidence for reduced symptom preoccupation, health anxiety, and healthcare utilization. CBT targets catastrophic misinterpretation of bodily sensations, attentional focus on the body, checking and reassurance-seeking, and avoidance. Exposure-based and acceptance/mindfulness approaches (ACT, mindfulness-based therapy) also show benefit, and internet-delivered CBT expands access.
Pharmacotherapy
SSRIs and SNRIs are the pharmacologic mainstay, useful both for the disorders themselves and for the frequently comorbid depression and anxiety. A landmark randomized trial in hypochondriasis found both fluoxetine and CBT superior to placebo, with the combination offering no clear advantage over either alone—supporting either as a reasonable first step. Because patients are often hypervigilant to bodily sensations and side effects, start low, go slow, and frame medication in terms of reducing worry and improving function rather than treating an imagined disease.
4. Course, Prognosis, and Pitfalls
Both disorders tend to be chronic and fluctuating, but engagement in structured care and CBT meaningfully improves symptoms, distress, and healthcare use. Prognosis is better with shorter duration, fewer comorbidities, a strong therapeutic alliance, and psychological-mindedness; it is worse with entrenched illness identity, significant secondary gain, and personality pathology.
5. Clinical Summary and Evidence-Based Recommendations
Key Takeaways for Clinical Practice
- Diagnose on positive criteria: disproportionate health-related thoughts, feelings, and behaviors—not the absence of a medical explanation. SSD can coexist with real disease.
- SSD vs. IAD: prominent distressing somatic symptoms (SSD) versus preoccupation with having/acquiring illness with minimal symptoms (IAD).
- Build the alliance: one coordinating clinician, scheduled brief visits, validation, and a goal of function over cure.
- Stop the workup treadmill: bound the evaluation, minimize unnecessary tests and referrals, and limit repeated reassurance in IAD.
- CBT first: the best-supported treatment; ACT/mindfulness and internet-CBT are useful alternatives.
- SSRIs/SNRIs help, particularly with comorbid depression and anxiety; start low given somatic hypervigilance.
6. Quick Reference: Somatic and Health-Anxiety Presentations
| Feature | SSD | IAD | Functional neurological disorder |
|---|---|---|---|
| Central problem | Distressing somatic symptoms + excessive health cognitions | Fear of having/getting serious illness | Neurological deficit incompatible with disease |
| Somatic symptoms | Present, prominent | Absent or mild | Present (motor/sensory) but functional |
| Medically explained? | May or may not be | Not the focus | Positive functional signs |
| Duration | ≥6 months (state persistent) | ≥6 months | Variable |
| First-line treatment | Collaborative care + CBT; SSRI/SNRI | CBT (exposure-based); SSRI | Education, physiotherapy, CBT |
References
- American Psychiatric Association. (2022). Diagnostic and Statistical Manual of Mental Disorders (5th ed., text revision). Washington, DC: American Psychiatric Association Publishing. [Somatic symptom disorder F45.1; Illness anxiety disorder F45.21]
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