Serotonin Syndrome — MRCPsych Paper B MCQ

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ModerateLiaison PsychiatrySerotonin SyndromeMRCPsych Paper B

A 42-year-old woman has taken sertraline 100 mg daily for 6 months. Four hours after receiving her first dose of tramadol for postoperative pain, she becomes agitated and diaphoretic. Her temperature is 39.1°C and pulse is 118 beats/min. Examination shows increased bowel sounds, brisk reflexes and bilateral inducible ankle clonus. What is the most likely diagnosis?

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Correct answer: D — Serotonin syndrome

The diagnosis is serotonin syndrome. Tramadol has serotonergic activity, and its addition to an SSRI can produce excessive serotonergic effects. The rapid onset, agitation, diaphoresis, hyperthermia, hyperreflexia and particularly inducible clonus are highly characteristic. Neuroleptic malignant syndrome is associated with dopamine antagonist exposure and usually prominent generalised rigidity rather than clonus. SSRI discontinuation syndrome requires recent dose reduction or cessation. Anaphylaxis would be suggested by urticaria, angioedema, bronchospasm or hypotension. Predominant tramadol opioid toxicity causes somnolence, miosis and respiratory depression. Serotonin syndrome is potentially life-threatening and requires urgent withdrawal of serotonergic agents and supportive medical management.

Reference: electronic Medicines Compendium, Tramadol hydrochloride 50 mg capsules, hard, Summary of Product Characteristics, sections 4.4 and 4.5, updated 9 July 2026. https://www.medicines.org.uk/emc/product/11799/smpc