Hemorrhagic colitis is one of the side effects of antimicrobial agents. It develops digestive symptoms such as diarrhea, bloody stool, abdominalgia, nausea and vomiting after or during drug administration. There were four cases of hemorrhagic colitis caused by antimicrobial agents after administration of amoxicillin (AMPC) in our department. The four patients were as follows : 50-year-old female, 38-year-old female, 34-year-old male, and 27-year-old female. They were administered antimicrobial agents because of phlegmon in the cheek, maxillary sinusitis, pericoronitis and post extraction. In all cases, severe abdominalgia and frequent diarrhea were observed at first and then the diarrhea gradually became bloody. Three patients required admission for 6-13 days and were treated for starvation by fluid therapy, and the symptoms were recovered from in all cases. Hemorrhagic colitis is not preventable because the cause is unknown. However, antimicrobial agents are needed for treatment of inflammantion. Therefore, antimicrobial agents should be used with caution of hemorrhagic colitis.
