Health Information




Acute confusional state; Acute brain syndrome

Delirium is sudden severe confusion due to rapid changes in brain function that occur with physical or mental illness.

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  • Causes

    Delirium is most often caused by physical or mental illness, and is usually temporary and reversible. Many disorders cause delirium. Often, the conditions are ones that do not allow the brain to get oxygen or other substances.

    Causes include:

    • Alcohol or sedative drug withdrawal
    • Drug abuse
    • Electrolyte or other body chemical disturbances
    • Infections such as urinary tract infections or pneumonia (more likely in people who already have brain damage from stroke or dementia)
    • Poisons
    • Surgery
  • Symptoms

    Delirium involves a quick change between mental states (for example, from lethargy to agitation and back to lethargy).

    Symptoms include:

    • Changes in alertness (usually more alert in the morning, less alert at night)
    • Changes in feeling (sensation) and perception
    • Changes in level of consciousness or awareness
    • Changes in movement (for example, may be slow moving or hyperactive)
    • Changes in sleep patterns, drowsiness
    • Confusion (disorientation) about time or place
    • Decrease in short-term memory and recall
    • Disorganized thinking, such as talking in a way that doesn't make sense
    • Emotional or personality changes, such as anger, agitation, depression, irritability, overly happy
    • Incontinence
    • Movements triggered by changes in the nervous system
    • Problem concentrating
  • Exams and Tests

    The following tests may have abnormal results:

    • An exam of the nervous system (neurologic examination), including tests of feeling (sensation), thinking (cognitive function), and motor function
    • Neuropsychological studies

    The following tests may also be done:

    • Blood and urine tests
    • Chest x-ray
    • Cerebrospinal fluid (CSF) analysis (spinal tap)
    • Electroencephalogram (EEG)
    • Head CT scan
    • Head MRI scan
    • Mental status test
  • Treatment

    The goal of treatment is to control or reverse the cause of the symptoms. Treatment depends on the condition causing delirium. The person may need to stay in the hospital for a short time.

    Stopping or changing medications that worsen confusion, or that are not necessary, may improve mental function. After asking about your medical history, your doctor will discuss medicines and substances that can worsen confusion, such as alcohol.

    Disorders that contribute to confusion should be treated. These may include:

    • Anemia
    • Decreased oxygen (hypoxia)
    • Heart failure
    • High carbon dioxide levels (hypercapnia)
    • Infections
    • Kidney failure
    • Liver failure
    • Nutritional disorders
    • Psychiatric conditions (such as depression)
    • Thyroid disorders

    Treating medical and mental disorders often greatly improves mental function.

    Medicines may be needed to control aggressive or agitated behaviors. These are usually started at very low dosages and adjusted as needed.

    Some people with delirium may benefit from hearing aids, glasses, or cataract surgery.

    Other treatments that may be helpful:

    • Behavior modification to control unacceptable or dangerous behaviors
    • Reality orientation to reduce disorientation
  • Outlook (Prognosis)

    Acute conditions that cause delirium may occur with chronic disorders that cause dementia. Acute brain syndromes may be reversible by treating the cause.

    Delirium often lasts about 1 week. It may take several weeks for mental function to return to normal . Full recovery is common, but depends on the underlying cause of the delirium.

  • Possible Complications

    • Loss of ability to function or care for self
    • Loss of ability to interact
    • Progression to stupor or coma
    • Side effects of medications used to treat the disorder
  • When to Contact a Medical Professional

    Call your health care provider if there is a rapid change in mental status.

  • Prevention

    Treating the conditions that cause delirium can reduce its risk. In hospitalized patients, avoiding sedatives, prompt treatment of metabolic disorders and infections, and using reality orientation programs will reduce the risk of delirium in those at high risk.

Related Information

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Mendez MF, Kremen SA. Delirium. In: Daroff RB, Fenichel GM, Jankovic J, Mazziotta JC, eds. Bradley's Neurology in Clinical Practice. 6th ed. Philadelphia, Pa: Elsevier Saunders; 2012:chap 4.

Smith JP, Seirafi J. Delirium and dementia. In: Marx JA, Hockberger RS, Walls RM, et al., eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. 8th ed. Philadelphia, Pa: Elsevier Mosby; 2013:chap 104.


Review Date: 2/10/2014  

Reviewed By: Joseph V. Campellone, M.D., Division of Neurology, Cooper University Hospital, Camden, NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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