Delirium is a serious disturbance in a person's mental abilities that results in a decreased awareness of one's environment and confused thinking. The onset of delirium is usually sudden, often within hours or a few days.

What is it?

  • Delirium is a serious disturbance in a person's mental abilities that results in a decreased awareness of one's environment and confused thinking. The onset of delirium is usually sudden, often within hours or a few days.
  • Delirium can usually be traced to one or more contributing factors, such as a severe or chronic medical illness, medication, surgery, or drug or alcohol abuse.
  • The symptoms of delirium and dementia are similar, and input from a family member or caregiver may be important for a doctor to make a diagnosis.


Signs and symptoms of delirium usually appear in a short period of time, from a few hours to a few days. The symptoms often fluctuate throughout the day. Therefore, a person may have periods of no symptoms.

The primary signs and symptoms of delirium include the following factors.

Reduced awareness of the environment

This may result in:

  • An inability to stay focused on a topic
  • Wandering attention
  • Getting stuck on an idea rather than responding to questions or conversation
  • Being easily distracted by unimportant things

Cognitive impairment, or poor thinking skills

This may appear as:

  • Poor memory, particularly of recent events
  • Disorientation, or not knowing where one is, who one is or what time of day it is
  • Difficulty speaking or recalling words
  • Rambling or nonsense speech
  • Difficulty understanding speech
  • Difficulty reading or writing

Other common symptoms

  • Seeing things that don't exist (hallucinations)
  • Agitation, irritability or combative behavior
  • Little or no activity or little response to the environment
  • Disturbed sleep habits
  • Extreme emotions, such as fear, anxiety, anger or depression

Delirium and dementia

Other medical conditions can result in symptoms associated with delirium. Dementia and delirium may be particularly difficult to distinguish, and a person may have dementia and delirium. In fact, the majority of cases of delirium occur in people with dementia.

Dementia is the progressive decline of memory and other thinking skills due to the gradual dysfunction and loss of brain cells. The most common cause of dementia is Alzheimer's disease.

Some common distinguishing differences between the symptoms of delirium and dementia include the following:

  • Onset. The onset of delirium occurs within a short time while dementia usually begins with relatively minor symptoms that gradually worsen over time.
  • Attention. The inability to stay focused or maintain attention is significantly impaired with delirium. A person in the early stages of dementia remains generally alert.
  • Fluctuation. The appearance of delirium symptoms can fluctuate significantly and often throughout the day. While people with dementia have better and worse times of day, their memory and thinking skills stay at a fairly constant level during the course of a day.

One type of dementia called Lewy body dementia is more difficult to distinguish from delirium because hallucinations and fluctuations in symptoms are common to both disorders.


Delirium occurs when the normal sending and receiving of signals in the brain becomes impaired. This impairment is most likely caused by a combination of factors that make the brain vulnerable and factors that trigger a malfunction in brain activity.

Factors that may make people more vulnerable to the development of delirium include:

  • Dementia
  • Older age
  • Limited ability to perform everyday activities
  • Visual or hearing impairment
  • Poor nutrition or dehydration
  • Severe, chronic or terminal illness
  • Multiple medical problems
  • Treatment with multiple drugs
  • Alcohol or drug abuse

Factors that are common triggers for delirium in vulnerable people include:

  • Medications
  • Multiple medications
  • Surgery
  • Sudden, severe illness
  • Infection
  • Excessive alcohol consumption
  • Use of recreational drugs
  • Alcohol or drug withdrawal
  • Emotional stress
  • Multiple medical procedures
  • Admission to intensive care

A number of medications can act as triggers of delirium, particularly:

  • Sleep medications
  • Narcotic pain relievers
  • Antidepressants
  • Parkinson's disease treatments
  • Drugs for treating spasms or convulsions
  • Allergy medications


Delirium may last only a few hours or as long as several weeks or months. If factors contributing to delirium are addressed, the recovery time is often shorter.

The degree of recovery depends to some extent on the health and mental status of a person before the onset of delirium. People with dementia, for example, may experience a significant overall decline in memory and thinking skills or a more rapid decline in skills. People in better health are more likely to recover fully.

People with other serious, chronic or terminal illnesses may not regain their pre-delirium levels of thinking skills or functional abilities. Delirium in seriously ill people is also more likely to lead to:

  • A general decline in health
  • Poor recovery from surgery
  • A need for institutional care
  • An increased risk of death


A doctor will diagnose delirium based on the answers to questions about a person's medical history, tests to assess mental status and the identification of possible contributing factors. An examination may include the following:

  • Mental status assessment. A doctor starts by assessing awareness, attention and thinking. This can be done informally through conversation, or more formally with tests or screening checklists that assess mental state, confusion, perception and memory.
  • Physical and neurological exams. The doctor will perform a physical exam, checking for signs of dehydration, infection, alcohol withdrawal and other problems. The physical exam can also help detect underlying disease. Delirium may be the first or only sign of a serious condition, such as respiratory failure or heart failure. A neurological exam — checking vision, balance, coordination and reflexes — can help determine if a stroke or another neurological disease is causing the delirium.
  • Other possible tests. If the cause or trigger of delirium can't be determined from the medical history or exam, the doctor may order blood, urine and other diagnostic tests. Brain-imaging tests, which require a certain degree of cooperation from the person being examined, are generally used when a diagnosis can't be made with other available information.

Treatments and drugs

The first goal of treatment for delirium is to address any underlying causes or triggering factors — by stopping use of a particular medication, for example, or treating an infection. Treatment then focuses on creating an optimal environment for healing the body and calming the brain.

Supportive care

Supportive care aims to prevent complications by protecting the airway, providing fluids and nutrition, assisting with movement, treating pain, addressing incontinence and keeping people with delirium oriented to their surroundings.

A number of simple, nondrug approaches have been found to help:

  • Clocks and calendars to help a person stay oriented
  • A calm, comfortable environment that includes familiar objects from home
  • Regular verbal reminders of current location and what's happening
  • Involvement of family members
  • Avoidance of change in surroundings and caregivers
  • Uninterrupted periods of sleep at night, with low levels of noise and little light
  • Open blinds during the day to promote daytime alertness and a regular sleep-wake cycle
  • Avoidance of physical restraints and bladder tubes
  • Use of music, massage and relaxation techniques to ease agitation
  • Opportunities to get out of bed, walk and perform self-care activities
  • Provision of glasses, hearing aids and interpreters as needed


Drug treatment is used to calm a person only when severe agitation or confusion:

  • Prevents the performance of a necessary medical exam or treatment
  • Endangers the person or threatens the safety of others
  • Doesn't lessen with nondrug treatments

The usual drug of choice is an antipsychotic medication, which may lessen the disorganized thinking that accompanies delirium.


The most successful approach to preventing delirium is to target risk factors that might trigger an episode. Hospital environments present a special challenge — frequent room changes, use of restraints, invasive procedures, loud noises, poor lighting and lack of natural light can worsen confusion.

Strategies that have been proved to help prevent delirium in hospitalized people include:

  • Simple and regular communication about current place and time
  • Regular identification of important people, such as doctors, nurses and family members
  • Stimulating activities
  • Mobility and range-of-motion exercises
  • Minimal use of psychoactive drugs
  • Uninterrupted sleep
  • Nondrug treatment for sleep problems or anxiety
  • Adequate fluids and nutrition
  • Use of eyeglasses, hearing aids and other adaptive equipment for vision or hearing impairment
  • Pain management

Coping and support

A person with delirium may require a long period of recovery either in a care facility or at home. People with dementia or a terminal illness or those approaching the end of life are at particularly high risk of delirium.

If you are a relative or caregiver of a person recovering from delirium or at risk of delirium, you can take steps to improve the person's health, prevent a recurrence and help you manage your responsibilities.

Sleeping well

You can promote good sleep habits with the following tips:

  • Keep inside lighting appropriate for the time of day.
  • Encourage exercise and activity during the day.
  • Offer warm, soothing, noncaffeinated beverages before bedtime.

Staying calm and well oriented

The following tips can help a person with delirium or at risk of delirium to remain calm and well oriented:

  • Provide a clock and calendar and refer to them regularly throughout the day.
  • Communicate simply about any change in activity, such as time for lunch or time for bed.
  • Keep familiar and favorite objects around but avoid a cluttered environment.
  • Approach the person calmly.
  • Identify yourself or other people regularly.
  • Avoid arguments.
  • Keep noise levels and other distractions to a minimum.
  • Help the person keep a regular daytime schedule.
  • Maintain and provide eyeglasses and hearing aids.

Preventing complicating problems

Help prevent medical problems by:

  • Giving the person his or her medication on a regular schedule
  • Providing plenty of fluids and a healthy diet
  • Encouraging regular exercise and activity

Caring for the caregiver

If you are providing regular care for a person with delirium or at risk of delirium, you may consider support groups, educational materials or other resources offered by nonprofit organizations, community health services and government agencies.

Organizations that may benefit you include the National Family Caregivers Association, the Alzheimer's Association and the National Institute on Aging.