Isolated venlafaxine-induced serotonin syndrome.

Serotonin syndrome is a potentially fatal complication of serotonergic drug therapy. Usually, serotonin syndrome occurs with the concomitant use of two serotonergic drugs; this case report describes a patient with a classic presentation of serotonin syndrome induced solely by a venlafaxine overdose. Emergency physicians need to be aware that the serotonin syndrome may occur not only with serotonergic drug combinations but also with overdoses of a single potent serotonergic agent such as venlafaxine.