Delirium is a state of mental confusion. It comes on quickly and causes significant changes in a person's thinking and behavior. People with delirium usually have trouble paying attention to what is going on or knowing where they are. They may become very withdrawn or very emotional and unable to sit still. They may even see or feel things that are not there (hallucinations). Delirium is a sign of a serious underlying medical condition.

What are the causes?

Delirium occurs when something suddenly affects the signals that the brain sends out. Brain signals can be affected by anything that puts severe stress on the body and brain and causes brain chemicals to be out of balance. The most common causes of delirium include:

  • Infections. These may be bacterial, viral, fungal, or protozoal.

  • Medicines. These include many over-the-counter and prescription medicines.

  • Recreational drugs.

  • Substance withdrawal. This occurs with sudden discontinuation of alcohol, certain medicines, or recreational drugs.

  • Surgery.

  • Sudden vascular events, such as stroke, brain hemorrhage, and severe migraine.

  • Other brain disorders, such as tumors, seizures, and physical head trauma.

  • Metabolic disorders, such as kidney or liver failure.

  • Low blood oxygen (anoxia). This may occur with lung disease, cardiac arrest, or carbon monoxide poisoning.

  • Hormone imbalances (endocrinopathies), such as an overactive thyroid (hyperthyroidism) or underactive thyroid (hypothyroidism).

  • Vitamin deficiencies.

What increases the risk?

This condition is more likely to develop in:

  • Children.

  • Older people.

  • People who live alone.

  • People who have vision loss or hearing loss.

  • People who have existing brain disease, such as dementia.

  • People who have long-lasting (chronic) medical conditions, such as heart disease.

  • People who are hospitalized for long periods of time.

What are the signs or symptoms?

Delirium starts with a sudden change in a person's thinking or behavior. Symptoms come and go (fluctuate) over time, and they are often worse at the end of the day. Symptoms include:

  • Not being able to stay awake (drowsiness) or pay attention.

  • Being confused about places, time, and people.

  • Forgetfulness.

  • Having extreme energy levels. These may be low or high.

  • Changes in sleep patterns.

  • Extreme mood swings, such as anger or anxiety.

  • Focusing on things or ideas that are not important.

  • Rambling and senseless talking.

  • Difficulty speaking, understanding speech, or both.

  • Hallucinations.

  • Tremor or unsteady gait.

How is this diagnosed?

People with delirium may not realize that they have the condition. Often, a family member or health care provider is the first person to notice the changes. The health care provider will obtain a detailed history of current symptoms, medical issues, medicines, and recreational drug use. The health care provider will perform a mental status examination by:

  • Asking questions to check for confusion.

  • Watching for abnormal behavior.

The health care provider may perform a physical exam and order lab tests or additional studies to determine the cause of the delirium.

How is this treated?

Treatment of delirium depends on the cause and severity. Delirium usually goes away within days or weeks of treating the underlying cause. In the meantime, the person should not be left alone because he or she may accidentally cause self-harm. Treatment includes supportive care, such as:

  • Increased light during the day and decreased light at night.

  • Low noise level.

  • Uninterrupted sleep.

  • A regular daily schedule.

  • Clocks and calendars to help with orientation.

  • Familiar objects, including the person's pictures and clothing.

  • Frequent visits from familiar family and friends.

  • Healthy diet.

  • Exercise.

In more severe cases of delirium, medicine may be prescribed to help the person to keep calm and think more clearly.

Follow these instructions at home:

  • Any supportive care should be continued as told by the health care provider.

  • All medicines should be used as told by the health care provider. This is important.

  • The health care provider should be consulted before over-the-counter medicines, herbs, or supplements are used.

  • All follow-up visits should be kept as told by the health care provider. This is important.

  • Alcohol and recreational drugs should be avoided as told by the health care provider.

Contact a health care provider if:

  • Symptoms do not get better or they become worse.

  • New symptoms of delirium develop.

  • Caring for the person at home does not seem safe.

  • Eating, drinking, or communicating stops.

  • There are side effects of medicines, such as changes in sleep patterns, dizziness, weight gain, restlessness, movement changes, or tremors.

Get help right away if:

  • Serious thoughts occur about self-harm or about hurting others.

  • There are serious side effects of medicine, such as:

    • Swelling of the face, lips, tongue, or throat.

    • Fever, confusion, muscle spasms, or seizures.

This information is not intended to replace advice given to you by your health care provider. Make sure you discuss any questions you have with your health care provider.