Delirium

Source: MedlinePlus Health Topics, U.S. National Library of Medicine

Last synced 8/10/2026Status: primary verified

What is delirium? Delirium is a mental state in which you are confused, disoriented, and not able to think or remember clearly. It usually starts suddenly. It is often temporary and treatable. There are three types of delirium: Hypoactive, when you are not active and seem sleepy, tired, or depressed Hyperactive, when you are restless or agitated Mixed, when you change back and forth between being hypoactive and hyperactive What causes delirium? There are many different problems that can cause delirium. Some of the more common causes include: Advanced cancer . Alcohol or drugs , either from intoxication or withdrawal. This includes a serious type of alcohol withdrawal syndrome called delirium tremens. It usually happens to people who stop drinking after years of alcohol use disorder (AUD) . Dehydration and electrolyte imbalances . Dementia . Hospitalization , especially in intensive care. Infections , such as urinary tract infections , pneumonia , and the flu . Medicines. This could be a side effect of a medicine, such as sedatives or opioids . Or it could be from withdrawal after stopping a medicine. Metabolic disorders . Organ failure , such as kidney or liver failure. Poisoning . Serious illnesses . Severe pain . Sleep deprivation . Surgeries , including reactions to anesthesia . Who is more likely to get delirium? Certain factors put you at risk for delirium, including: Being in a hospital or nursing home Having dementia Having a serious illness or more than one illness Having an infection Older age Having surgery Taking medicines that affect the mind or behavior Taking high doses of pain medicines , such as opioids What are the symptoms of delirium? The symptoms of delirium usually start suddenly, over a few hours or a few days. They often come and go. The most common symptoms include: Changes in alertness (usually more alert in the morning, less at night) Changing levels of consciousness Confusion Disorganized thinking, talking in a way that doesn't make sense

Educational only

This information is for general education and is not medical advice. Always talk to a licensed U.S. clinician about your situation, medications, or treatment decisions.