Serotonin syndrome in patients with headache disorders.

Serotonin syndrome (SS) is an iatrogenic, drug-induced syndrome caused by serotoninergic agent. Various serotonergic drugs are used in different headache disorders. Therefore, a possibility of developing SS exists in patients with headache. Herein, we are reporting two patients with headache disorders who developed SS.Case 1: a 49-year-old man had a 6-year history of episodic cluster headache (CH). However, he had never been diagnosed with CH before reporting to us. He had been receiving amitriptyline, tramadol/acetaminophen combination and flunarizine. Lithium was started for CH. He developed features consistent with SS. The patient responded to cyprohepatdine.Case 2: a 36-year-old chronic migraineur was on amitriptyline. Addition of sodium valproate led to the development of new features that fulfilled the criteria of SS. The patient responded to cyprohepatdine.As SS may be fatal, there is a need to increase awareness about SS in physicians treating patients with headache.