Delirium is sudden confusion.


Causes of delirium are not well known. It can be caused by an injury or illness that affects the brain.

Brain Tumor
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Risk Factors

Delirium is more common in older adults. Other things that may raise the risk are:

  • Having severe health problems, such as dementia, stroke, seizures, or tumors
  • Having infections, such as pneumonia or a urinary tract infection
  • Alcohol or drug abuse
  • A head injury
  • A severe lack of sleep or fluids
  • Problems passing stool


Symptoms happen quickly. They may be:

  • Memory problems
  • Disorientation
  • Being very upset
  • Being withdrawn
  • Being aggressive
  • Sleepiness
  • Language problems
  • Seeing, hearing, or feeling things that are not there
  • Believing things that are not based in reality


The doctor will ask about your symptoms and health history. A physical exam will be done. A cognitive exam will also be done. This may be enough to make the diagnosis.

These tests may be done when more information is needed:

  • Blood and urine tests
  • An MRI or CT scan to take pictures of the brain


Most people will get better when the cause of the delirium is treated, such as treating an infection. Symptoms may also need to be treated. This can be done with:


Some medicine may need to be stopped or changed.

Medicines to treat delirium may be:

  • Antipsychotics
  • Benzodiazepines to treat alcohol or drug withdrawal


Delirium is hard to prevent as it starts quickly and has many causes.


American Psychiatric Association

National Institute of Mental Health


Canadian Psychiatric Association

Canadian Psychological Association


Delirium in hospitalized patients. EBSCO DynaMed website. Available at: Updated September 24, 2019. Accessed October 18, 2019.

Inouye SK, Westendorp RG, et al. Delirium in elderly people. Lancet. 2014 Mar 8;383(9920):911-22, commentary can be found in Lancet 2014 Jun 14;383(9934):2044.

4/29/2016 DynaMed Plus Systematic Literature Surveillance Litton E, Carnegie V, et al. The efficacy of earplugs as a sleep hygiene strategy for reducing delirium in the ICU: a systematic review and meta-analysis. Crit Care Med. 2016;44(5):992-999.

Last reviewed September 2019 by EBSCO Medical Review Board Rimas Lukas, MD  Last Updated: 8/7/2020