Delirium tremens is a severe form of alcohol withdrawal that involves sudden and severe mental or nervous system changes. Delirium tremens can occur when you stop drinking alcohol after a period of heavy drinking, especially if you do not eat enough food. Delirium tremens may also be caused by head injury, infection, or illness in people with a history of heavy alcohol use. Delirium tremens is the most severe form of ethanol withdrawal; it is manifested by altered mental status (global confusion) and sympathetic overdrive (autonomic hyperactivity), which can progress to cardiovascular collapse. This is a medical emergency with a high mortality rate, making early recognition and treatment essential. History of heavy alcohol use and either reduction or cessation of drinking prior to presentation.