Linezolid-associated peripheral and optic neuropathy, lactic acidosis, and serotonin syndrome.

Linezolid is an oxazolidinone antibacterial agent indicated for serious gram-positive infections. Only minor adverse effects were seen in phase III trials. However, more serious adverse effects were reported after commercial release, including cases of lactic acidosis, peripheral and optic neuropathy, and serotonin syndrome. Peripheral and optic neuropathy was usually seen after several months of linezolid therapy (median 5 mo), lactic acidosis after several weeks (median 6 wks), and serotonin syndrome after several days (median 4 days). Death occurred in two of seven reported cases of lactic acidosis, and three of 15 reported cases of serotonin syndrome. Improvement or complete recovery occurred in all cases of optic neuropathy, whereas complete recovery failed to occur in any patient with peripheral neuropathy. Linezolid should be discontinued immediately in patients experiencing these adverse effects. Patients receiving linezolid for more than 28 days should be monitored for signs of peripheral and optic neuropathy.