Serotonin syndrome from linezolid and SSRI interaction — SCE Acute Medicine MCQ

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ModerateToxicology and OverdoseSerotonin syndrome from linezolid and SSRI interactionSCE Acute Medicine

A 40-year-old woman taking sertraline is given linezolid for resistant pneumonia. She becomes febrile and agitated with diarrhoea, tremor, inducible clonus and hyperreflexia. CK is mildly raised and pupils are dilated. What is the most likely diagnosis?

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Correct answer: E — Serotonin syndrome

Linezolid has monoamine oxidase inhibitory activity and can precipitate serotonin syndrome with SSRIs. Clonus and hyperreflexia are particularly helpful distinguishing signs from neuroleptic malignant syndrome, which is usually slower with lead-pipe rigidity. Anticholinergic toxicity causes dry skin and reduced bowel sounds rather than diarrhoea and clonus. Management is stopping serotonergic drugs, supportive care and specialist advice.

Reference: BNF interactions, TOXBASE serotonin syndrome