The serotonin syndrome: initial misdiagnosis.

BACKGROUND: The selective serotonin reuptake inhibitors are major drugs used in psychiatry today. While serotonin syndrome has become more frequent in an overdose situation and when an interacting drug is given, the toxicity of SSIRs is less than that of most other psychiatric drugs. Although the characteristics of toxicity are defined, it seems that physicians are not aware of the phenomenon.

OBJECTIVES: To investigate patients with serotonin syndrome who were initially misdiagnosed.

METHODS: We conducted a retrospective chart review of seven patients admitted in the last 2 years with mild to severe serotonin syndrome who were initially diagnosed as having other diseases.

RESULTS: Most patients (5/7) were initially diagnosed with exacerbation of their psychiatric disorder. Gastroenteritis was diagnosed in two patients. One patient was suspected of having a metastatic lesion in the brain, and severe drug overdose was diagnosed in one patient. They all recovered after withholding the culprit drugs.

CONCLUSIONS: This report is an addition to the growing literature on misdiagnosis of psychiatric patients. Serotonin toxicity should be considered in patients in whom the combination of mental changes, neuromuscular abnormalities and autonomic hyperactivity are features of acute disease.