Core features

• Preoccupation with having or acquiring a serious illness for at least 6 months (duration may vary by specific concerns).
• Somatic symptoms are absent or, if present, are mild in intensity; anxiety is disproportionate to medical findings.
• High health‑related behaviours (repeated checking, doctor‑shopping, repeated tests) or maladaptive avoidance (avoiding medical care) are present.
• Functional impairment and distress are marked, and preoccupation persists despite reassurance.

Common presentations & triggers

• Focusing on bodily sensations (palpitations, headache, GI sensations) and interpreting them as signs of serious disease.
• Triggers include a recent medical diagnosis in self/family, exposure to medical information online, or health crises (pandemics).
• Some patients present with somatic symptom disorder where somatic complaints are prominent — differentiate by degree of somatic symptoms vs illness anxiety focus.

Assessment checklist

1. History: onset, specific feared illnesses, health‑related behaviours, healthcare utilisation, prior tests/procedures, and response to reassurance.
2. Mental state: comorbid anxiety, depression, OCD traits, checking behaviours and suicidal ideation if present.
3. Medical review: targeted physical exam and investigations based on red flags — avoid excessive tests driven by patient reassurance‑seeking unless clinically indicated.
4. Functional impact: work absence, relationship strain, financial costs of investigations and adherence to medical advice.

Differential diagnosis

• Somatic symptom disorder (prominent somatic complaints), generalized anxiety disorder, panic disorder (focus on acute somatic sensations), OCD (health‑related obsessions) and factitious/malingering (intentional feigning).
• Identify medical conditions that could explain symptoms — red flags should prompt targeted investigation.

Evidence‑based psychological treatments

• Cognitive Behavioural Therapy (CBT) for health anxiety: first‑line — addresses catastrophic misinterpretations, checking behaviours, safety‑seeking, and intolerance of uncertainty. Includes behavioural experiments, exposure to feared health scenarios, and response prevention.
• Mindfulness & ACT: acceptance and commitment strategies reduce preoccupation and increase engagement in valued activities.
• Brief interventions: empathic explanation, structured follow‑up plans, and single‑session CBT techniques can be effective in primary care settings when specialist access limited.

Pharmacotherapy

• SSRIs (e.g., sertraline, escitalopram) are effective for severe illness anxiety and comorbid anxiety/depressive disorders; start at standard doses and monitor response.
• Short‑term use of anxiolytics may be considered for severe agitation, but avoid long‑term benzodiazepines due to dependence and paradoxical effects on anxiety.
• Medication is usually adjunctive to CBT, not a substitute.

Primary care management strategies — pragmatic tips

• Establish a single, trusted clinician as the point of contact and agree a time‑limited plan for investigations and follow‑up to reduce doctor‑shopping and repeated tests.
• Use scheduled appointments rather than unscheduled visits for reassurance‑seeking; provide clear safety netting for red‑flag symptoms and document agreed plan in records.
• Provide psychoeducation about the mind–body connection and normalize anxiety while avoiding dismissive language; introduce brief CBT techniques (worry time, behavioural experiments).

Practical resources & follow‑up

• Use brief validated tools to monitor severity (Health Anxiety Inventory, PHQ‑9, GAD‑7) and record progress.
• Provide written care plans and self‑help resources (guided CBT workbooks, reputable online modules) and arrange regular reviews to reinforce agreed limits on investigations.

Key takeaways

• Illness anxiety disorder is characterised by persistent health worry with excessive checking or avoidance despite reassurance; it causes substantial distress and healthcare use.
• First‑line treatment is CBT tailored to health anxiety; SSRIs are effective adjuncts for severe or comorbid presentations.
• In primary care, use a single clinician model, scheduled follow‑ups and clear safety‑netting to reduce unnecessary investigations and maintain the therapeutic relationship.