skip to main content

Severe serotonin toxicity after linezolid–sertraline co-administration — MRCEM SBA MCQ

Instant feedback + full explanation. One question, done properly.

HardToxicology and environmental emergenciesSevere serotonin toxicity after linezolid–sertraline co-administrationMRCEM SBA

A 62-year-old man taking sertraline is assessed in the emergency department seven hours after his first dose of linezolid for a resistant skin infection. He is confused and diaphoretic, with spontaneous ankle clonus, brisk lower-limb reflexes and generalised rigidity. Both drugs have been stopped. Despite intravenous diazepam and active external cooling, his core temperature has risen from 39.2 °C to 40.5 °C over 25 minutes. An anaesthetist is at the bedside. Which management plan should take priority?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: E — Proceed to intubation with paralysis, continue active cooling and arrange intensive care admission.

The onset after linezolid was added to sertraline, together with spontaneous clonus and hyperreflexia, identifies serotonin toxicity. His rapidly rising temperature and rigidity indicate severe disease. Initial sedation and cooling have not controlled the hyperthermia, so the priority is anaesthetist-led intubation and neuromuscular paralysis while cooling continues, followed by intensive care admission. UK clinical literature recommends escalation to intubation and paralysis when cooling and sedation are ineffective. ([medicines.org.uk](https://www.medicines.org.uk/emc/product/13583/smpc?utm_source=openai)) A is attractive because benzodiazepines are appropriate initial treatment, but repeating diazepam alone does not adequately address this deterioration. B offers a recognised serotonin antagonist; it may be considered as an adjunct, but its uncertain efficacy makes it a poor substitute for immediate supportive escalation. C is plausible because dantrolene can reduce muscle activity and may be considered in hyperthermic syndromes; it does not take priority over airway management and paralysis here. D treats ordinary fever but does not control the muscle activity responsible for this hyperthermia. If sedation and cooling were controlling the temperature, continued supportive treatment rather than immediate intubation would be reasonable. ([dtb.bmj.com](https://dtb.bmj.com/content/60/6/88.abstract?utm_source=openai))

Reference: Linezolid 600 mg Film-Coated Tablets: Summary of Product Characteristics (Current product information; date not stated on the retrieved page) — https://www.medicines.org.uk/emc/product/13583/smpc Serotonin syndrome (2022) — https://dtb.bmj.com/content/60/6/88.abstract Management of serotonin syndrome (toxicity) (2025; electronically published 26 June 2024) — https://pubmed.ncbi.nlm.nih.gov/38926083/