Serotonin syndrome induced by low-dose venlafaxine.
OBJECTIVE
To report the case of a patient with serotonin syndrome induced by low-dose venlafaxine.


METHODS
A 29-year-old Taiwanese woman with major depressive disorder abruptly developed serotonin syndrome during low-dose (37.5 mg/d) venlafaxine monotherapy, with symptoms of restlessness, tremor, shivering, diarrhea, vomiting, ataxia, tachycardia, and myoclonus. The patient recovered in 2 hours after receiving prochlorperazine and lorazepam in the emergency department. Venlafaxine was discontinued, and she was discharged home. Two weeks later, the patient started to receive fluoxetine 20 mg/d and reported no adverse adverse effects during follow-up clinic visits.


CONCLUSIONS
The clinical manifestations of this case meet Sternbach's criteria of serotonin syndrome. Its possible etiologic factors include panic attack, adverse drug reaction, pharmacodynamic interaction, and congenital absence of CYP2D6 enzyme activity. The Naranjo probability scale suggested a probable causality of venlafaxine treatment and serotonin syndrome.


CONCLUSIONS
Clinicians should be aware of the risk of serotonin syndrome when the patient receives not only a combination of 2 antidepressants, but also the single potent serotonergic agent venlafaxine.
Pan
Jan-Jhy
JJ
Department of Psychiatry, Taipei Medical University-Wan Fang Hospital, Taipei, Taiwan.
Shen
Winston W
WW
D000328:Adult; D003511:Cyclohexanols / Q000009:adverse effects*; D003866:Depressive Disorder / Q000188:drug therapy*; D005260:Female; D006801:Humans; D020230:Serotonin Syndrome / Q000139:chemically induced*; D000069470:Venlafaxine Hydrochloride
D003511:Cyclohexanols; D000069470:Venlafaxine Hydrochloride