FFinalistSouthampton · 2027
Psychiatry
AKT · Psychiatry/Anxiety & stress

Obsessive-compulsive disorder

Overview

Obsessions (intrusive, unwanted, anxiety-provoking thoughts/images/urges) and/or compulsions (repetitive behaviours or mental acts performed to neutralise them), recognised as excessive, time-consuming or impairing.

Recognise

  • Obsessions: contamination, harm, symmetry, taboo thoughts
  • Compulsions: washing, checking, counting, ordering, reassurance-seeking
  • Insight usually retained; ego-dystonic

Red flags

  • High suicide risk, or harm-themed obsessions misread as intent — refer/consult specialist

Differentials & how to tell them apart

Generalised anxietyrealistic worries, not ritualised neutralising
OCPD (personality)ego-syntonic perfectionism, no true obsessions/compulsions
Body dysmorphic disorderpreoccupation focused on appearance
PsychosisOCD insight retained; delusions are held as true

Investigations

Clinical; severity by functional impairment (Y-BOCS in specialist care). Screen for depression (common comorbidity).

Management

  1. 1Mild functional impairment: low-intensity CBT including exposure and response prevention (ERP, ≤10 therapist-hours).
  2. 2Moderate: offer a choice of intensive CBT+ERP OR an SSRI.Gate: Clomipramine as alternative first-line drug only if SSRI contraindicated, preferred, or previously effective
  3. 3Severe: combined SSRI + CBT(ERP); refer to secondary care mental health team.
SSRI (e.g. sertraline, fluoxetine) — needs HIGHER dose and ≥12 weeks for response
Clomipramine — alternative first-line drug if SSRI contraindicated/preferred or prior good response

Key points

OCD-specific: SSRIs need higher doses and longer (≥12 weeks) than in depression. Continue ≥12 months after response.

Monitor & prognosis

Y-BOCS/functioning; SSRI dose adequacy; comorbid depression and suicide risk.

Chronic, fluctuating; ERP + SSRI effective.

Source: NICE CKS OCD (2025) / CG31