A case of acute hyperammonemic encephalopathy after initiation of 5-fluorouracil chemotherapy

5-fluorouracil is a chemotherapeutic agent that has been used for decades to treat a number of neoplasms. It has a number of adverse effects; however, we present a case of a seldom reported side effect in hyperammonemic encephalopathy that should be considered in patients presenting with altered mental status shortly after starting therapy.