Causes

Who's at risk for delirium?

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Delirium is a sudden change in a person’s mental state and ability to think clearly. It happens most often in older people who have a serious illness. There's a greater risk if the person has dementia. But delirium can happen at any age. And it doesn't always happen in someone with a serious illness.

Delirium is seen as an emergency. It needs to be looked at by a healthcare provider right away.


What raises a person’s risk?

Delirium can happen while a person is being treated for an illness or other serious health condition. It can also happen after surgery. The person may be in a hospital or nursing home. Or they may be at home. Delirium often goes unrecognized in older adults.

A person is at risk for delirium if they have 1 or more of these:

  • Current dementia or cognitive impairment

  • A past episode of delirium

  • Depression

  • Are age 75 or older

  • Any serious illness, such as cancer, heart attack, or metabolism problem such as those linked to kidney or liver failure

  • Been admitted to intensive care in a hospital

  • Physical restraints

  • Been using or are withdrawing from drugs or alcohol

  • Past or current brain injury or disease

  • A bladder catheter

  • An infection

  • Broken bones, especially those that need surgery

  • Sleep problems because of light, noise, or other disruptions

  • Constant or severe pain that isn't well-managed

  • Fluid loss (dehydration)

  • Poor nutrition

  • Poor eyesight or hearing

  • Several tests or treatments in a short time

  • Not able to move or have pain with movement

  • Recent surgery with anesthesia


Medicines that raise the risk of delirium

Certain medicines can raise a person’s risk of having delirium. They include:

  • Prescription medicines. This includes sedatives, narcotics, antispasmodics, antibiotics, muscle relaxants, steroids, high blood pressure medicine, antacids, antidepressants, heart medicines, nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, and pain medicines, especially opiates.

  • Over-the-counter medicines. This includes allergy medicine, cough medicine, sleeping pills, and antinausea medicine. Diphenhydramine, found in many allergy and sleeping pills, is a very common cause.

  • Some herbal medicines

  • Psychoactive medicines


If you know someone at risk

Delirium is an emergency. If you think that your loved one has delirium, call 911 right away.

Author: Wheeler, Brooke

© 2000-2026 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.

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