Serotonin syndrome
Serotonin toxicity as a dose-related spectrum, the drug combinations that cause severe cases, the Hunter criteria, how to tell it from NMS and anticholinergic toxicity, and management from benzodiazepines and cyproheptadine to paralysis and cooling.
Tier 1Condition
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- Serotonin toxicity is an excess of serotonin in the central and peripheral nervous system, caused by drugs. It is concentration-dependent, not idiosyncratic: more serotonin means worse toxicity.
- Mild cases are common after SSRI overdose. Life-threatening cases nearly always involve an MAOI combined with another serotonergic drug.
- Diagnosis is clinical, using the Hunter criteria. Look for clonus.
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Sources
- Therapeutic Guidelines: Toxicology and Toxinology (December 2024 update, including new tramadol and tapentadol monographs)AU/NZTherapeutic Guidelines Limited, 2024
- Poisons Information Centre (13 11 26)AU/NZNSW Poisons Information Centre, Sydney Children's Hospitals Network
- Dunkley EJ, Isbister GK, Sibbritt D, Dawson AH, Whyte IM. The Hunter Serotonin Toxicity Criteria: simple and accurate diagnostic decision rules for serotonin toxicity. QJM 2003;96:635-42AU/NZQJM, 2003
- Isbister GK, Buckley NA, Whyte IM. Serotonin toxicity: a practical approach to diagnosis and treatment. Med J Aust 2007;187:361-5AU/NZMedical Journal of Australia, 2007
- Boyer EW, Shannon M. The serotonin syndrome. N Engl J Med 2005;352:1112-20New England Journal of Medicine, 2005
- Last updated
- 14 November 2026
What changed
- 14 November 2026 Personal emails, About story and Australian-style copy