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What Causes Delirium?

Delirium is an abrupt change in the brain that causes mental confusion and emotional disruption. It makes it difficult to think, remember, sleep, pay attention, and more. You might experience the condition during alcohol withdrawal, after surgery, or with dementia. Delirium is usually temporary and can often be treated effectively.

Types of Delirium

Delirium is categorized by its cause, severity, and characteristics:

  • Delirium tremens is a severe form of the condition suffered by people who are trying to stop drinking. Usually, they have been drinking large amounts of alcohol for many years.
  • Hyperactive delirium is characterized by being highly alert and uncooperative.
  • Hypoactive delirium is more common. With this type, you tend to sleep more and become inattentive and disorganized with daily tasks. You might miss meals or appointments.

Some people have a combination of both hyperactive and hypoactive delirium, alternating between the two states.

What Causes Delirium?

Diseases that cause inflammation and infection, such as pneumonia, can interfere with brain function. Additionally, taking certain medications (e.g., blood pressure medicine) or abusing drugs can disrupt chemicals in the brain. Alcohol withdrawal and eating or drinking poisonous substances can also cause delirium.

When you have trouble breathing due to asthma or another condition, your brain doesn’t get the oxygen it needs. Any condition or factor that significantly changes your brain function can cause severe mental confusion.

Who Is at Risk for Delirium?

If you’re over 65 and/or have numerous health conditions, you’re more at risk for delirium. Surgery patients and people withdrawing from alcohol and drug abuse are also more at risk. Conditions that damage the brain (e.g., stroke and dementia) can increase the risk. Your risk is also higher if you are under extreme emotional stress. The following factors may also contribute to delirium:

  • sleep deprivation
  • certain medications (e.g., sedatives, blood pressure medications, sleeping pills, and painkillers)
  • dehydration
  • poor nutrition
  • infection (e.g., urinary tract infection)

Symptoms of Delirium

Delirium affects your mind, emotions, muscle control, and sleep patterns. You might have a hard time concentrating or feel confused about your whereabouts. You may also move more slowly or quickly than usual, and experience mood swings. Other symptoms include:

  • not thinking or speaking clearly
  • sleeping poorly and feeling drowsy
  • reduced short-term memory
  • loss of muscle control (e.g., incontinence)

How Is Delirium Diagnosed?

Confusion Assessment Method

Your doctor will observe your symptoms and examine you to see if you can think, speak, and move normally. Some health practitioners use the Confusion Assessment Method (CAM) to diagnose or rule out delirium. The doctor observes whether or not:

  • your behavior changes throughout the day, especially if you’re hospitalized
  • you have a hard time paying attention or following others as they speak
  • you’re rambling

Tests and Exams

Many factors can cause changes in brain chemistry. Your doctor will try to determine the cause of the delirium by running tests relevant to your symptoms and medical history. One or more of the following tests may be needed to check for imbalances:

  • blood chemistry test
  • head scans
  • drug and alcohol tests
  • thyroid tests
  • liver tests
  • chest X-ray
  • urine tests

How Is Delirium Treated?

Depending on the cause of the delirium, treatment may include taking or stopping certain medications. Counseling may also be helpful in certain cases. In older adults, an accurate diagnosis is important for treatment, as delirium symptoms are similar to dementia — but the treatments are very different.


Your doctor will prescribe medications to treat the underlying cause of delirium. For example, if your delirium is caused by a severe asthma attack, you might need an inhaler or breathing machine to restore your breathing. If a bacterial infection is causing the delirium symptoms, antibiotics may be prescribed.

In some cases, your doctor may recommend that you stop drinking alcohol or stop taking certain medications (e.g., codeine or other drugs that depress your system). If you’re agitated or depressed, you may be given small doses of one of the following medications:

  • antidepressants to relieve the depression
  • sedatives to ease alcohol withdrawal
  • dopamine blockers to help with drug poisoning
  • thiamine to help prevent confusion


If you’re feeling disoriented, counseling may help to anchor your thoughts. Counseling is also used as a treatment for people whose condition makes them engage in dangerous behaviors. In all cases, counseling is intended to make you comfortable and give you a safe place to discuss your thoughts and feelings.

Recovering from Delirium

Full recovery from delirium is possible with the right treatment. It can take up to a few weeks for you to think, speak, and feel physically like your old self. You might have side effects from the medications used to treat this condition.

Content licensed from:

Written by: Chitra Badii
Medically reviewed on: Jan 29, 2016: Mark R Laflamme, MD

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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