Acute hemorrhagic colitis associated with oral administration of oseltamivir for the treatment of influenza A.

The importance of oseltamivir as a strategy for the treatment of influenza has been recognized; however, the risk of acute hemorrhagic colitis should be considered, although it is rare. This report describes a case of acute hemorrhagic colitis in a 61-year-old Japanese man after the oral administration of oseltamivir for influenza A. A definitive diagnosis of influenza A was made using a rapid diagnosis kit. Abdominal pain, diarrhea, and hematochezia occurred the day after the first administration of oseltamivir (The patient had taken two capsules of oseltamivir). Endoscopic examination revealed extensive acute hemorrhagic colitis. Histopathological examination of the colonic mucosa revealed small atrophic glands with partial deciduation of the epithelium and a decrease in the number of goblet cells. Hemorrhage and mild infiltration of inflammatory cells were observed as well. These changes were suggestive of an ischemic change. A culture test showed normal flora.