Linezolid was initially discovered as an antidepressant because of its effect on 
blocking intracellular metabolism of serotonin, norepinephrine, and other 
biogenic amines. As time passed, it was realized that linezolid possessed 
antibacterial activity, and linezolid has been developed and marketed as such. 
In medicine we are quick to categorize drugs into specific classes as a 
mechanism to recall indication and use. By classifying linezolid as an 
antibacterial, it is common to forget about its antidepressant roots. A case 
report involving linezolid with citalopram and mirtazepine in the precipitation 
of serotonin syndrome in a critically ill bone marrow transplant patient is 
described in this article.