• Clinical science



Delirium is a neurocognitive disorder characterized by impaired attention, awareness (reduced orientation to the environment), and other disturbed cognitive functions (e.g., memory, language, or perception). Symptoms develop acutely and tend to fluctuate throughout the day. Delirium occurs as a direct physiological consequence of another medical condition. It is most often a complication of polypharmacy, especially in elderly patients, and is also commonly seen in patients admitted to the ICU. Although delirium is a reversible confusional state, it warrants urgent medical attention because it may be the first sign of serious underlying disease. Treatment of delirium focuses on treating the underlying illness and reducing exposure to exacerbating factors. Antipsychotic medications are used for the treatment of agitation in delirious patients.


For the major causes of delirium, think I WATCH DEATH: Infection, Withdrawal, Acute metabolic disorder, Trauma, CNS pathology, Hypoxia, Deficiencies, Endocrine, Acute vascular, Toxins/drugs, Heavy metals.


Clinical features

  • The main symptom is an acute (hours to days) alteration in the level of awareness and attention.
  • Other features may include:
    • Illusions
    • Hallucinations
    • Deficits in memory
    • Reversal of the sleep-wake cycle
    • Emotional lability
    • Agitation, combativeness
  • The severity of symptoms fluctuates throughout the day and worsens in the evening (termed sundowning).
  • The duration of symptoms depends on the underlying illness.



  • If the cause of delirium is not obvious based on the patient history and physical findings:
  • If the patient has focal neurological deficits or the initial workup is negative, further tests may include:
    • Neuroimaging (CT, MRI)
    • Lumbar puncture: to rule out meningitis/encephalitis
    • EEG: usually shows diffuse slowing of background activity in patients with delirium; also useful in patients with a history of head trauma, stroke, or brain lesions
  • Further diagnostics that may be considered:


Differential diagnoses

In older patients, it is important to differentiate delirium from dementia.

Delirium vs. dementia
Delirium Dementia
  • Insidious
  • Rapid and fluctuating
  • Hours to days
  • Slowly progressive deterioration
  • Months to years
Level of consciousness
  • Decreased
  • Intact
  • Impaired (fluctuating)
  • Usually alert
  • Impaired in the advanced phase
  • Recent memory loss
  • Recent, then remote memory loss
Thought process
  • Disorganized
  • Impoverished
  • Present (often visual or tactile)
  • Present in 30% of patients in the advanced phase
Psychomotor activity
  • Increased or decreased
  • Usually normal
  • Usually abnormal
  • Usually normal
  • Reversible
  • Usually irreversible

The differential diagnoses listed here are not exhaustive.


  • Identify and treat the underlying cause.
  • Discontinue the causative medications (e.g., benzodiazepines and anticholinergics).
  • Supportive medical care
    • Manage agitation initially with nonpharmacologic strategies (see “Prevention” below).
    • Administer antipsychotics if the patient is agitated and/or poses harm to themselves or others.
    • Maintain adequate hydration and nutrition.
    • Reduce pain, preferably with nonopioid medications.
    • Prevent aspiration, incontinence, and skin breakdown.

Benzodiazepines are deliriogenic. Do not treat delirious patients with benzodiazepines unless the delirium is due to alcohol or benzodiazepine withdrawal, in which case haloperidol is contraindicated because it lowers the seizure threshold!



  • Nonpharmacologic approach
    • Reduce exposure to modifiable risk factors.
    • Reorient the patient regularly.
    • Arrange for regular visits from family and friends.
    • Arrange for constant observation, preferably by a family member or friend.
    • Reduce the amount of noise, procedures, and medication administration occurring at night.
    • Provide physical and occupational therapy to mobilize the patient as soon as possible.
    • Minimize the use of restraints as much as possible.
    • Provide visual and hearing aids for patients with impairments.
  • Pharmacologic


last updated 05/13/2020
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