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 doctor right away.

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 one or more of these:

• Current dementia or cognitive impairment
• A past episode of delirium
• Depression
• Are age 65 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

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

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