Hypersensitivity reactions associated with fidaxomicin use.

We report hypersensitivity reactions associated with fidaxomicin, an antibacterial drug approved for the treatment of Clostridium difficile-associated diarrhea. These reactions are viewed as significant because of severity and unexpected because fidaxomicin is minimally absorbed. The fidaxomicin labeling was revised to include information about the possibility of hypersensitivity reactions.