Probable Serotonin Syndrome and Withdrawal Symptoms Caused by Milnacipran

A 70-year-old woman, residing in a nursing home, was admitted to our hospital because of cerebral hemorrhage. She had excessive sweating, a temperature above 37°C, and intermittent muscle spasm such as myoclonus, since the time of admission. We suspected that these symptoms were related to side effects caused by the milnacipran she was taking for depression, prior to hospitalization. After we discontinued milnacipran, the patient began exhibiting withdrawal symptoms such as excitement and insomnia. When we substituted milnacipran with mianserin, the withdrawal symptoms diminished and the excessive sweating and involuntary movement disappeared. Serotonin-norepinephrine reuptake inhibitor (SNRI) and selective serotonin reuptake inhibitor (SSRI) have been widely utilized in the clinic to treat depression; serious side effects such as serotonin syndrome and withdrawal syndrome associated with their discontinuation, have been reported. However, it is unlikely that serotonin syndrome and withdrawal syndrome due to a precedent use of milnacipran would have been reported. This case was suspected to be related to serotonin syndrome and withdrawal syndrome from the course of treatment. This case provides valuable information for addressing new similar cases caused by milnacipran.