Ifosfamide is a nitrogen mustard alkylating agent used in the treatment of cancer. Hemorrhagic cystitis is rare when ifosfamide is given together with mesna. A common and dose-limiting side effect is encephalopathy (brain dysfunction). It occurs in some form in up to 50% of people receiving the agent. The reaction is probably mediated by chloroacetaldehyde, one of the breakdown products of the ifosfamide molecule, which has chemical properties similar to acetaldehyde and chloral hydrate. The symptoms of ifosfamide encephalopathy can range from mild (difficulty concentrating, fatigue), to moderate (delirium, psychosis), to severe (nonconvulsive status epilepticus or coma). In children, this can interfere with neurological development. Apart from the brain, ifosfamide can also affect peripheral nerves. The severity of the reaction can be classified according to either the National Cancer Institute or the Meanwell criteria (grade I-IV).