Zyvox (linezolid) is an oral medication used primarily to treat severe infections caused by bacteria that are resistant to other medications, such as streptococci, methicillin resistant S. aureus (MRSA), and vancomycin-resisant enterococci (VRE). These bacteria usually cause pneumonia and skin infections. It is part of a class of medications called oxazolidinone antibiotics, and it works by interfering with the growth and division of bacteria.