A 28-year-old woman presents to the psychiatry clinic with a 3-year history of intrusive thoughts that her hands are contaminated with harmful bacteria, despite frequent handwashing. She washes her hands 15–20 times daily, often until they bleed, yet the anxiety persists. She recognizes these thoughts as irrational but feels unable to resist the urge to wash. Her work performance has declined, and she avoids social gatherings. She denies low mood, anhedonia, or suicidal ideation. What is the most appropriate first-line pharmacological intervention?

Explanation

## Diagnosis **Key Point:** This patient meets DSM-5 criteria for Obsessive-Compulsive Disorder (OCD): presence of obsessions (intrusive thoughts about contamination) and compulsions (repetitive handwashing), recognition of irrationality, significant functional impairment, and duration >1 month. ## First-Line Pharmacotherapy **High-Yield:** SSRIs are the first-line pharmacological treatment for OCD in most international guidelines (APA, NICE, CANMAT). Sertraline is commonly used with a recommended dose range of 50–200 mg daily, often requiring higher doses than those used for depression. **Clinical Pearl:** OCD typically requires: - Higher SSRI doses than depression (200 mg sertraline vs. 50–100 mg for MDD) - Longer trial duration (8–12 weeks) before assessing response - Slower titration to minimize side effects ## Why Sertraline Is Correct 1. **First-line evidence:** SSRIs (sertraline, paroxetine, fluoxetine) have the strongest evidence base for OCD [cite:DSM-5 Diagnostic Criteria for OCD] 2. **Dose-response:** Sertraline 200 mg is an effective target dose for OCD 3. **Tolerability:** Better side-effect profile than clomipramine in most patients 4. **Combination potential:** Can be augmented with cognitive-behavioral therapy (CBT) or antipsychotics if inadequate response ## Comparison with Other Options | Agent | Role in OCD | Limitation | |-------|-------------|----------| | Sertraline (SSRI) | First-line | — | | Clomipramine (TCA) | Second-line/alternative | Higher anticholinergic burden, cardiac effects, drug interactions | | Alprazolam (benzodiazepine) | Adjunct for acute anxiety only | Risk of dependence, no evidence for OCD remission, contraindicated as monotherapy | | Haloperidol (typical antipsychotic) | Augmentation only (if SSRI inadequate) | Not monotherapy; extrapyramidal side effects | **Mnemonic: SSRI-OCD** — SSRIs are the Selective Serotonin Reuptake Inhibitors of choice for Obsessive-Compulsive Disorder.