Mental Confusion or Delirium

Approved by the Cancer.Net Editorial Board, 03/2020

Mental confusion, also called delirium, is a change in a person’s awareness. Confusion affects how a person thinks, sees the world around them, and remembers things.

The main signs of mental confusion or delirium are sudden changes in awareness. A person with confusion or delirium might suddenly get very sleepy and unaware of their surroundings or act very upset and nervous. The person will not recognize this change in themselves and is most often noted by family members or medical providers.

Who gets mental confusion or delirium?

Confusion is the most common sign that cancer or treatment is affecting the brain. It is a common problem for people with any advanced illness including advanced cancer or those at the end of life. A person with mental confusion will think and act very differently from normal. The condition can be difficult and stressful for the person affected as well as their loved ones. It may also make it harder for the health care team to care for other symptoms.

How does someone with mental confusion act?

There are 3 types of confusion.

  • Hypoactive, or low activity. Acting sleepy or withdrawn and "out of it."

  • Hyperactive, or high activity. Acting upset, nervous, and agitated.

  • Mixed. A combination of hypoactive and hyperactive confusion.

Mixed mental confusion is the most common. More than 2 in every 3 people who have mental confusion go back and forth between types.

What are the symptoms of mental confusion?

The main symptom is a change in general awareness and consciousness. This may include:

  • A shorter attention span

  • Trouble remembering things, writing, or finding words

  • Speech and thoughts that do not make sense

  • Not knowing where they are, what day it is, or other facts

  • Mixing up day and night and difficulty sleeping

  • Personality changes, restlessness, anxiety, depression, or irritability

  • Seeing things that others do not (hallucinating) or believing things that are not really happening (delusions)

What causes mental confusion?

Mental confusion may have more than 1 cause. This is especially true if a person is weak or very sick. Finding the cause is important so their doctor can choose the best treatment. Here are some possible causes.

Medications. Medications that can cause mental confusion include:

  • Chemotherapy drugs

  • Pain medications

  • Anti-nausea or allergy medications

  • Steroid medications

  • Sleep medications

  • New medications for other conditions

A person may develop confusion or delirium if they suddenly stop taking certain medications, especially if they have previously been taking these medications for a prolonged period.

Organ problems. Mental confusion or delirium can happen if certain organs are not working correctly. These can include the liver, kidneys, heart, or lungs. Seizures or cancer that has spread to the brain can cause delirium.

Problems with fluid and electrolyte balance. The balance of fluids and minerals called electrolytes keeps your brain and body working correctly. Having much more or much less than normal can cause mental confusion. Things that can upset the balance include:

  • Too much of the mineral calcium in the blood.

  • Dehydration. This might happen if you are nauseated, vomiting, or having trouble swallowing. Diarrhea and urinating a lot can also cause dehydration.

  • Too much fluid in the body. Heart, kidney, or liver failure can cause this.

  • Too much or too little sugar in the blood.

Infection. Bladder, lung (pneumonia), brain, and blood infections (sepsis) can cause mental confusion and delirium. Sepsis is a life-threatening condition that happens when an infection spreads to your bloodstream.

Not enough oxygen in the blood. Health problems that cause low levels of oxygen in the blood can cause mental confusion. These include lung or heart problems, blood clots, and sleep problems.

How do doctors diagnose mental confusion?

Doctors will take a comprehensive history and physical exam, including a neurological exam to diagnose mental confusion. Based on this medical history and exam, additional tests and scans may be recommended as well.

How can mental confusion be treated?

Finding the underlying cause of mental confusion and treating it is the most effective solution. The doctor may recommend that the person with confusion or delirium stops taking certain medications or takes new medications to treat the underlying cause or to ease symptoms. Other treatments may be also be required. It is important to work closely with the health care team to find a solution.

There are things that can be done to help the person feel more comfortable and less confused. Here are some ideas:

  • Find a reassuring environment. This might be a quiet room with good light and familiar people and objects. It may also help to place a clock and wall calendar nearby.

  • If the person is hallucinating, ask the health care team to create a plan to help manage the hallucinations. They can help you learn what to expect and how to manage these symptoms.

  • Medications called antipsychotics may be useful to help alleviate certain symptoms. There can be side effects, but most of these can be managed well.

Relieving side effects is an important part of cancer care and treatment. This is called palliative care or supportive care. Talk with your health care team about any symptoms of mental confusion, or delirium. This includes any new symptoms or a change in symptoms.

Mental confusion at the end of life

Mental confusion or delirium is common at the end of a person's 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 it is unpleasant or scary, treatment can help.

There are several medications available that can make a person with confusion or delirium more comfortable. The doctor may recommend sedation if a person with delirium is very agitated and they do not improve with other treatments. Sedation is medication that puts a person into a deep sleep. The goal of sedation is to make the person feel comfortable, not to speed up death. It may be hard for family and friends when their loved one does not interact as much.

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

Related Resources

Care Through the Final Days

Caring for a Loved One

When You Have to Make Decisions for a Loved One With Cancer