Mild serotonin syndrome associated with concurrent linezolid and fluoxetine.

PURPOSE: A case of serotonin syndrome that developed during concurrent linezolid and fluoxetine is presented.
SUMMARY: A 23-year-old white male patient was originally admitted to receive intravenous chemotherapy for acute myelogenous leukemia. He had a history of intravenous amphetamine abuse, hepatitis B virus infection, hepatitis C virus infection, depression, and bipolar disorder. The patient's routine medications before admission included methadone, fluoxetine, voriconazole, transdermal nicotine patch, lorazepam, and quetiapine. The patient developed persistent neutropenia and complications from chemotherapy, including mild mucositis. Despite treatment with levofloxacin, acyclovir, and voriconazole, the patient developed high fevers. Levofloxacin was discontinued and aztreonam and vancomycin were started. After a blood culture revealed that the bacteria were likely vancomycin resistant, vancomycin was discontinued and linezolid was initiated. Nine hours later, the patient began complaining of severe pain in his abdomen. After a total of four doses of linezolid, the patient reported further discomfort. Two days after linezolid initiation, a health care team member identified the interaction between fluoxetine and linezolid as the cause of the patient's symptoms, and linezolid was discontinued. All symptoms resolved within 48 hours. While resolution generally occurs within 24-48 hours after discontinuing the offending agent, the time to resolution may be delayed if the agent has a long half-life or active metabolites, in which case admission to an intensive care unit is recommended. Cyproheptadine and chlorpromazine may also be used to treat symptoms.
CONCLUSION: Serotonin syndrome developed in a patient taking concurrent linezolid and fluoxetine.