Delirium is a change in cognitive status that comes on quickly and suddenly over a number of hours or days. People with diseases, including cancer, that have progressed beyond the earlier stages are at risk for delirium, as are older people and people with dementia.


Delirium in people with cancer has many possible causes, including:

  • primary brain tumors or cancer that has spread to the brain or meninges
  • changes in metabolism
  • infection
  • not getting enough oxygen
  • lung, liver or kidney failure
  • poor nutrition
  • not having enough fluids in the body (dehydration)
  • problems with electrolyte levels in the body
  • syndrome of inappropriate antidiuretic hormone (SIADH)
  • chemotherapy drugs and other medicines
  • radiation therapy damage to the brain (encephalopathy)

Delirium is often caused by a combination of these problems.

Signs and symptoms

General signs and symptoms of delirium include:

  • confusion – not knowing what day or time it is, or where they are
  • forgetfulness, problems with remembering things that have recently happened
  • rambling speech, not making sense with words or answers
  • not being able to focus or think clearly
  • hallucinations – seeing, feeling or hearing something that doesn’t exist
  • change in sleeping patterns

Delirium can be divided into 3 types. Each has its own signs and symptoms.

Hypoactive delirium is the most common type of delirium found in people with advanced cancer. Signs include slow or decreased speech, lowered level of awareness and little movement or activity. People with hypoactive delirium can become extremely sleepy and lethargic.

Hyperactive delirium has signs such as restlessness, agitation, anxiety and frequent mood changes. People with hyperactive delirium may be irritable, frustrated, angry, fearful or excited. They may also become physically aggressive.

Mixed delirium has signs of both hypoactive and hyperactive delirium, and the person will go from having signs of one type to showing signs of the other.

Delirium has some of the same signs and symptoms as dementia, so it can be hard to tell them apart. The main difference between delirium and dementia is that symptoms for delirium come on quickly, while the symptoms of dementia develop slowly over a period of time.

Family members are often the first people to notice the signs of dementia, as they know the person best. If you notice any personality or behaviour changes in someone with advanced cancer, tell the healthcare team right away.


The healthcare team will try to find what is causing the delirium. The medicines that a person is taking will be looked at to see if they may be causing the delirium.

Tests are done to try to find the underlying cause of delirium and may include:

Depending on test results, more tests may be done to make a diagnosis, such as:

Managing delirium

Talk to your healthcare team about treatments for delirium and how these treatments fit with your decisions about care. Treatment doesn’t always improve delirium in people with advanced cancer. In some cases, especially if the person with cancer is nearing the end of life, you may decide not to treat delirium.

The type of treatment offered for delirium will depend on the test results. Treatments may include:

  • changing medicines or doses of medicines, or stopping medicines
  • giving fluids with needles placed in the skin (subcutaneous) to treat dehydration
  • antibiotics to treat an infection
  • pain control
  • giving oxygen
  • removing a catheter from the bladder

The healthcare team will also try to create a calm environment for someone with delirium by:

  • making sure there is good natural lighting in the room during the day and that the room is dark at night
  • reducing noise in the room or hallway
  • providing a clock or calendar in the room
  • limiting the number of visitors
  • making sure that the person’s sleep isn’t interrupted for medical rounds

If the person with delirium is becoming distressed or upset or if it seems they might harm themselves or someone else, the healthcare team may use medicine to help ease these symptoms. There are no standard medicines for cancer-related delirium but the following drugs may be offered:

  • olanzapine (Zyprexa)
  • quetiapine (Seroquel)
  • aripiprazole (Abilify)

Side effects of these drugs may include:

  • feelings of restlessness
  • drowsiness
  • dizziness
  • abnormal movements (extrapyramidal side effects)

Methylphenidate (Ritalin) may be used in people with hypoactive delirium who aren’t having hallucinations or delusions and if the underlying cause of the delirium can’t be found. Side effects include nausea, dizziness and trouble sleeping.

If someone with delirium is very restless or agitated, the healthcare team may offer sedative medicines for a short amount of time. These may include lorazepam (Ativan) and midazolam (Versed). Side effects of these drugs include drowsiness and dizziness. Sedative medicines also increase the risk of falls.

Helping someone who has delirium

Some of these suggestions may help the person you know with delirium.

  • Bring some familiar things from home, like a couple of photographs or a favourite blanket.
  • Play the person’s favourite music softly in the background.
  • Speak with a quiet and reassuring voice. Give gentle reminders on what day and time it is, where they are, who they are and who you are.
  • Reduce restlessness and help keep a person with delirium active by going on short walks.
  • Try to have someone with the person as much as possible. Family members can take shifts to make sure someone is there around the clock.

Coping with delirium

Delirium can be upsetting to family members, especially if their loved one becomes aggressive or unkind. Try to remember that people who have delirium aren’t aware of how they’re acting and their actions do not reflect their true feelings or beliefs.

Delirium can also be upsetting to the person who has recovered from it. They may feel confused, guilty or ashamed of what they said or did.

The healthcare team can give you information and support to help you understand about delirium.

Expert review and references

  • Bush SH. Delirium: Information for Palliative Care Patients and their Families. Bruyere; 2017:
  • Bush SH, Lawlor PG, Ryan K, et al . Delirium in adult cancer patients: ESMO Clinical Practice Guidelines. Annals of Oncology. 2018.
  • Bush SH, Tierney S & Lawlor PG . Clinical assessment and management of delirium in the palliative care setting. Drugs. 2017.
  • Irwin, SA, Buckholz GT, Pirrello RD, Hirst, JM, Ferris FD . Recognizing and managing delirium. Berger AM, Shuster JL Jr, Von Roenn JH (eds.). Principles and Practice of Palliative Care and Supportive Oncology. 4th ed. Philadelphia: Lippincott Williams & Wilkins; 2013: 40: 529-542.
  • Johnson RJ III . A research study review of effectiveness of treatments for psychiatric conditions common to end-stage cancer patients: needs assessment for future research and an impassioned plea. BMC Psychiatry. 2018:
  • National Cancer Institute. Delirium (PDQ®) Health Professional Version. 2016.
  • National Cancer Institute. Delirium and cancer treatment. 2017.
  • Nolan C & DeAngelis LM . The confused oncologic patient: a rational clinical approach. Current Opinion in Neurology. 2016.

Medical disclaimer

The information that the Canadian Cancer Society provides does not replace your relationship with your doctor. The information is for your general use, so be sure to talk to a qualified healthcare professional before making medical decisions or if you have questions about your health.

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