Delirium Cause

What Causes Delirium and What You Can Do
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Anyone can develop delirium, a state of acute mental confusion that's a sudden decline from usual. But people with dementia are especially vulnerable, both to developing delirium and to suffering from its complications.

Delirium can have many different causes. In fact, a single episode can have multiple triggers. Most often, the underlying cause is some kind of stress to the body, especially illness. Caregivers who are alert to common causes of delirium can help avoid delirium triggers and ensure that their loved one receives swift treatment if needed.

Common causes of delirium

The actual underlying cause of delirium is usually one of the following:

A serious physical illness

Delirium may be the first sign of an infection, most commonly urinary tract infections or pneumonia.

Another common medical trigger for delirium is a low oxygen state, which can be brought on by an illness such as a heart attack or an exacerbation of congestive heart failure or COPD.

When blood chemistry or hormonal status is disordered for any reason, this can also cause delirium. Examples: abnormal blood sugar, calcium, potassium, or sodium levels; thyroid problems; liver or kidney disease. Dehydration is another common cause of delirium among older adults.


Medication side effects or interactions are perhaps the most common causes of delirium in someone with dementia who's not already in the hospital. That's because many commonly prescribed drugs worsen confusion in someone with dementia. Experts estimate that up to 30 percent of cases of delirium are caused or worsened by medications.

Especially common culprits:

  • Medications from a class known as anticholinergics, which includes drugs for overactive bladder, itching/allergy, vertigo, nausea, and certain drugs for nerve pain or depression. Diphenhydramine, or Benadryl, is a commonly used anticholinergic that's often included in over-the-counter sleep aids and PM-version painkillers.

  • Sedatives, tranquilizers, and antipsychotics. Examples include Ambien (sedative), Valium (tranquilizer), Zyprexa (antipsychotic).

  • Opiate painkillers, especially during the first few days of use.

Inadequately treated pain

Pain itself can cause delirium -- especially after surgery or a fracture. So while opiate drugs, for example, can cause delirium in some circumstances, they shouldn't be avoided at all costs, especially in an older adult with dementia. With a little extra attention, doctors usually can manage pain appropriately with these and other drugs.

Anesthesia or surgery

Up to 50 percent of postsurgical patients may be affected by delirium. This may be caused by post-op pain, as well as by the sheer physical stresses of undergoing anesthesia and surgery. An older adult who has dementia and may have other diseases is already under significant physical stress even before going under the knife.

Alcohol or other drugs

Excessive use of -- or withdrawal from -- alcohol, drugs, or prescription drugs (especially tranquilizers or antidepressants) can create a state of delirium.

Severe emotional stress

Mind and body are deeply interconnected, of course. Intense emotional stress can lead to the physical effect of delirium. Any kind of change in the everyday environment of a person with dementia can lead to this kind of duress. Examples: a new living arrangement, the loss of a familiar caregiver, the death of a spouse or loved one.

Sleep deprivation

Ongoing disruptions in sleep are another example of the emotional-physical cascade that can lead to delirium. For example, a patient in a hospital may be awakened often, at all hours. Or complications of dementia or another illness may cause insomnia that simply adds up.

Who is especially likely to get delirium

It's good to know who's particularly vulnerable to the causes of delirium, so you can be alert to situations that deserve special monitoring. The following factors put an older adult at higher risk of developing delirium:

  • Having had previous episodes of delirium

  • Being hospitalized, especially if in intensive care or after surgery

  • Being on multiple medications

  • Poor vision and/or hearing

  • Dehydration

  • Alcohol and/or drug abuse

Learn what to do if you suspect your loved one may be showing signs of delirium.