Serotonin Syndrome

This case is written by Dr. Donika Orlich. She is a PGY5 Emergency Medicine resident at McMaster University who also completed a fellowship in Simulation and Medical Education last year.

Why it Matters

This case is an example of why it is important to keep a broad differential in our patients. It would be easy to assume this patient has sepsis and to form cognitive biases around only this as a possible presentation. Instead, by maintaining a broad differential diagnosis, a relatively rare presentation is recognized. This case highlights the following:

  • The presenting features of serotonin syndrome: agitation, confusion, clonus, and hyperthermia
  • The management priorities in serotonin syndrome include both minimizing patient agitation with benzodiazepines and aggressive cooling
  • The potential for sodium channel blockade (and a resultant wide QRS pattern on ECG) with cocaine use
  • The potential for patients with a prolonged QT interval to develop Torsades de Pointes
  • The need to treat Torsades de Pointes with magnesium sulfate and defibrillation

Case Summary

A 27-year-old female presents hot and altered to the ED with EMS. Likely cause is serotonin syndrome, precipitated by being on citalopram and methadone in the setting of a recent cocaine binge (all increase serotonin levels). She will develop Torsades de Pointes as a complication which must be treated with MgSO4. She will become increasingly agitated and febrile, requiring IV benzodiazepines, active cooling, and consideration of intubation with paralysis to achieve normothermia.

Clinical Vignette

A 27-year-old female was found by her boyfriend this morning seeming confused and warm. He called EMS. She has a history of opioid abuse and is on methadone, but he swears that she has takes this as prescribed and has not done any prescription pain meds lately. They did “party a lot yesterday,” but she was otherwise well, with no complaints of fever before today. With EMS the patient was noted to be diaphoretic, febrile and quite agitated. She has been placed in a resuscitation bay.

Download the case here: Serotonin Syndrome

1st ECG for the case (long QT and wide QRS) found here:

Wide QRS

(ECG source:

2nd ECG for the case (long QT) found here:


(ECG source:

3rd ECG for the case (Torsades de Pointes) found here:

Torsades ECG

(ECG source:

Normal CXR found here:

normal female CXR radiopedia

(CXR source:

Post-intubation CXR found here:


(CXR source:

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