5-Fluorouracil–induced Encephalopathy in a 51-year-old Man

A case of hyperammonaemic encephalopathy that developed during the administration of a widely used chemotherapy regimen is reported in a 51-year-old man. 5-Fluorouracil was considered to be the causative agent. Although encephalopathy is a rare toxic effect of 5-fluorouracil, this case illustrates a serious and potentially life-threatening complication during a chemotherapy regimen using 5-fluorouracil. If patients develop unexplained changes in mental status during intravenous infusion of high-dose 5-fluorouracil, hyperammonaemic encephalopathy should be considered, and chemotherapy should be discontinued immediately. The plasma ammonia level, arterial blood gas content, and plasma lactate level should be