Skip to main content

ACS & ASCO are Stronger Together: Cancer.Net content is now available on



Managing Cancer Care

Confusion and Delirium

Confusion and delirium affect how a person thinks and behaves. When someone is confused or delirious, they can't think clearly and might not behave like they usually do. It most often goes away, but can be a sign that something serious is wrong.

What are confusion and delirium?

Confusion means a person can’t think clearly. People who are confused may think more slowly. They can have trouble focusing and understanding what’s going on around them. Confusion might last for a short time or can continue for longer.

Delirium affects memory and thinking. It is a more severe kind of confusion. It changes the way a person behaves and sees the world around them. Delirium comes on quickly and will often resolve after the cause is treated.

There are three types of delirium:

  • Hypoactive: The person may act tired or sleepy
  • Hyperactive: The person may seem to be restless or agitated
  • Mixed: At different times, the person may experience either hypoactive or hyperactive delirium

What causes confusion and delirium?

Many things can cause confusion and delirium in people with cancer. Often there is more than one cause. Some things that can lead to confusion and delirium are:

  • Cancer, especially if it is in the brain or the fluid around the brain
  • Cancer treatments, such as some types of chemotherapy and immunotherapy, radiation to the brain, surgery, and stem cell or bone marrow transplant
  • Some medicines used with cancer treatment, such as steroids and those used to prevent or treat nausea, allergies, loss of appetite, or sleep problems
  • Electrolyte level changes in the blood, such as high calcium, low blood sugar, low magnesium, low phosphorous, or low sodium
  • Infection or high fever
  • Severe pain
  • Not getting enough oxygen to the brain
  • Anemia
  • Problems with how some organs are working
  • Not getting enough fluid or healthy food
  • Not being active

Confusion and delirium also happen more often in people who:

Symptoms of confusion and delirium

The first symptom of confusion or delirium is often a sudden change in how alert a person is. They might become very sleepy and out of touch with what’s going on around them. Or they might start to act very upset and nervous. Most often, the person will not be aware of these changes, but their family members or cancer care team will notice them.

Other symptoms might include:

  • Changes in ability to speak, with long pauses or slurred words
  • Sudden changes in emotion, such as quick shifts from happy to irritated
  • Changes in behavior or personality
  • Changes in mood, such as anxiety or depression
  • Not thinking clearly or not knowing where they are
  • Forgetting what they were doing
  • Trouble paying attention
  • Needing help doing things like bathing and dressing

These symptoms can come and go. They can get worse at certain times, such as at night, or if the person is in a new place.

Delirium may cause hallucinations. People may see, hear, smell, or feel things that others cannot. But the hallucinations feel real to the person with delirium. People with delirium may also have delusions, believing things that are not based in reality. For instance, they might believe that someone is trying to harm them when that person is only trying to help.

Treatment for confusion and delirium

Treatment for delirium and confusion depends on the cause. Many times, treating the cause will ease or get rid of delirium or confusion. The cancer care team will do an assessment to look at any physical causes or medicines that might be causing the confusion or delirium. They may also want to do some tests, such as blood work, to try and find the cause.

Not all causes of delirium and confusion can be treated. This is often true when a person is nearing the end of their life. In that case, making the person comfortable may be the best option.

To get treatment started as soon as possible, the person with cancer or their caregiver needs to let the cancer care team know right away about changes.

Tips for dealing with confusing and delirium

  • Call your cancer care team right away or tell someone close to you if you have times when you feel confused or have other symptoms of delirium.
  • Ask someone to stay with you to keep you safe.
  • Try to stay in a room or other place where you feel comfortable and with people you know.

What caregivers can do

Caring for someone who is confused or has delirium can be hard. Changes in how they behave might make family and friends anxious or afraid.

The type of care that your loved one needs will depend on how confused they are and other symptoms they may have. Here are some things you can do to help keep your loved one safe and as comfortable as possible.

Provide a comforting and safe environment

  • Set up a quiet room with good light and familiar people and objects.
  • Tell your loved one the date and time, and where they are. It might help to place a clock and wall calendar where your loved one can see them.
  • Reassure the person who is confused that someone they know will stay with them.
  • When speaking to your loved one, focus their attention by touching them and standing in their line of sight. Let them know who you are. It might help to turn off background noise, like the TV or radio.
  • Play soft, soothing music when the person is in a room alone.
  • Use a night light so that your loved one can see where they are.
  • Label commonly used rooms and items with pictures. For example, put a picture of a toilet on the bathroom door and a picture of a flame over the stove.
  • Keep medicines out of reach between doses.

Help the person with delirium or confusion with daily activities

  • You may need to help your loved one with physical care, such as bathing, going to the toilet, preparing food, etc.
  • When helping the person with confusion or delirium, tell them what you are going to do and explain each step as you go along.
  • Check to see that your loved one eats and drinks enough. They may forget to eat or may not be able to eat on their own.
  • Encourage them to be as active as they can to keep up their strength. They may need someone with them to reduce the risk that they will fall.

Talk with the doctor or cancer care team

  • You or other family members may need to help make care decisions. It helps to have a primary caregiver who has been assigned to make decisions.
  • Go to appointments with the person who has confusion or delirium. Describing any signs of confusion or delirium you’ve seen can be helpful. You can also help your loved one remember what they’re told during appointments.
  • Talk to the cancer care team about the medicines your loved one is taking. Some may make the confusion or delirium worse. There also might be medicines that could help make your loved one more comfortable.
  • If your loved one has hallucinations, ask the cancer care team what you can do to help manage them.
  • Let the cancer care team know if you are having trouble managing your loved one’s care. They may have resources to help you and your loved one.

Know how and when to get help

Make sure you know who to call on your loved one's cancer care team and how to reach them, including when the office or clinic is closed.

Call the cancer care team as soon as possible if your loved one:

  • Becomes more confused
  • Has any sudden changes in their ability to do routine tasks or care for themselves
  • Becomes very restless
  • Hurts themselves or someone else in some way

Confusion at the end of life

Many people have confusion and delirium at the end of their life. Some people believe that hallucinations at the end of life are part of the dying process. Treatment may not be needed if the hallucinations are not upsetting. For example, people may see family members or friends who have already died. This can be comforting. But if the hallucinations are scary, treatment can help.

There are medicines that can make a person with confusion or delirium more comfortable. The cancer care team may suggest sedation if a person is very agitated and not getting better with other treatments. Sedation can make the person who is dying more comfortable.

Deciding how to treat confusion or delirium depends on what the person with cancer would like. If possible, people should talk with their cancer care team about their treatment options ahead of time and think about putting their health care wishes in writing.

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as editors and translators with extensive experience in medical writing.

American Society of Clinical Oncology. Mental confusion or delirium. Accessed at on December 1, 2023.

Cleveland Clinic. Confusion. Accessed at on December 7, 2023.

El Majzoub I, Abunafeesa H, Cheaito R, Cheaito MA, Elsayem AF. Management of altered mental status and delirium in cancer patients. Ann Palliat Med. 2019;8(5):728-739. doi:10.21037/apm.2019.09.14

Desimini EM. Altered mental status. In: Bush NJ & Gorman LM, eds. Psychosocial Nursing Care Along the Cancer Continuum. Oncology Nursing Society; 2018: 183-201.

National Cancer Institute. Delirium: Cancer Treatment Side Effect . Accessed at on December 1, 2023.

Francis J & Young GB. Diagnosis of Delirium and Confusional States. In, UpToDate, Post TW (Ed), UpToDate. Accessed at on December 5, 2023.

Last Revised: March 13, 2024

American Cancer Society Emails

Sign up to stay up-to-date with news, valuable information, and ways to get involved with the American Cancer Society.