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Last updated: April 8, 2021

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Delirium is a neurocognitive disorder characterized by impairments in attention and awareness (reduced orientation to the environment), as well as other cognitive disturbances (e.g., in memory, language, or perception). Symptoms develop acutely and tend to fluctuate throughout the day. Delirium occurs most commonly in elderly patients and is typically secondary to another medical condition or polypharmacy. Although delirium is a reversible confusional state, it warrants urgent medical attention because it may be the first sign of serious underlying disease. Management of delirium focuses on treating the underlying illness and providing supportive care until the confusion resolves. Antipsychotic medications may be used to manage agitation if other measures fail.

  • Delirium: a syndrome of acute confusion characterized by fluctuations in awareness, cognition, and attention, that fulfills the diagnostic criteria (e.g., DSM-5 or “Confusion assessment method” criteria)
  • Subsyndromal delirium: proposed term for patients with clinical features of delirium that do not fulfill the criteria for a delirium diagnosis. [1]
  • Acute encephalopathy
    • A pathobiological process in the brain that:
      • Is diffuse (i.e., without an associated structural lesion)
      • Develops rapidly (i.e., within hours to days, but < 4 weeks)
      • Can manifest as delirium, stupor, or coma
    • Can be further specified according to the suspected underlying mechanism, e.g., acute toxic-metabolic encephalopathy

References: [1][2]

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

  • The main symptom is an acute (hours to days) alteration in the level of awareness and attention.
  • Other features may include:
  • The severity of symptoms fluctuates throughout the day and worsens in the evening (termed sundowning).
  • Symptoms are reversible; their duration and severity depend on the underlying illness.
  • Delirium is commonly described based on the type of alteration that is seen:
Psychomotor activity Patient groups
Mixed type delirium Fluctuates or stays at baseline Most common type in the general population
Hypoactive delirium Decreased Most common type in the elderly population
Hyperactive delirium Increased (agitation) Usually seen in delirium due to substance use or substance withdrawal

Delirium is diagnosed clinically, based on either the DSM 5 or Confusion Assessment Method (CAM) criteria. Further studies should be conducted to determine the underlying etiology.

Delirium should be considered a medical emergency until proven otherwise; it can be a sign of severe underlying pathology and is associated with increased mortality. [5]

Diagnostic criteria [6][7][8]

Confusion assessment method (CAM)

CAM can be used in the community and most hospital environments to assess delirium; for patients in the ICU or the recovery room, use the modified version, CAM-ICU. [9]

Confusion assessment method (CAM) [7][8]
Feature Definition Description
Feature 1
  • Acute onset with fluctuating course
Feature 2
  • Inattention
  • The patient has trouble focusing, keeping track of the conversation, or can be easily distracted.
Feature 3
  • Altered consciousness
Feature 4
  • Thinking is disorganized.
  • The patient's speech is unclear, they seem incoherent, or the flow of ideas is illogical.

Diagnosis of delirium requires features 1 and 2 PLUS either feature 3 or 4.

DSM-5 diagnostic criteria for delirium

The patient meets all of the following:

  • Attention and awareness are impaired.
  • Acute onset over hours or days with waxing and waning severity
  • ≥ 1 additional disruption in cognition
  • The condition fulfills the following criteria:
    • Absence of preexisting dementia, coma, or severely reduce responsiveness
    • Evidence of an organic underlying cause

Routine laboratory studies [8][10]

The following studies are recommended in all patients with a new presumptive delirium diagnosis. Depending on the underlying etiology, the results may be normal.

Further diagnostic studies

These should be guided by clinical suspicion of the underlying process or conducted if no other cause has been identified with routine tests.

Symptom-based diagnostic workup for delirium
Suspected underlying process Concerning features Diagnostic studies
Nutritional (e.g., vitamin deficiencies)
Toxic (e.g., intoxication or withdrawal)
  • History of alcohol or recreational drug use
  • Suspicion of CO poisoning
Psychiatric [15]

Diagnosis of delirium is clinical. Identify the underlying precipitating factors for DELIRIUM: Drugs, Electrolyte abnormalities, Lack of medication (withdrawal), Infection, Reduced sensorial input, Intracranial pathology, Urinary retention or fecal impaction, Myocardial and pulmonary disease. [8]

The symptoms of delirium overlap with a number of other neurological disorders; additionally, patients with preexisting neurological diseases such as dementia are more vulnerable to developing delirium.


Delirium is most often confused with dementia. However, there are significant differences in the presentation of diseases.

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, then remote memory loss
Thought process
  • Disorganized
  • Impoverished
  • Present (often visual or tactile)
  • Can be present in advanced disease
Psychomotor activity
  • Increased or decreased
  • Usually normal
  • Usually abnormal
  • Usually normal
  • Reversible
  • Usually irreversible

Other differential diagnoses [16]

The differential diagnoses listed here are not exhaustive.

General principles

  • Treatment of the underlying condition: the mainstay of management
    • Consider discontinuing; or reducing the dose of causative medications, e.g., anticholinergics. [8][10]
    • See “Etiology” for a detailed list of conditions.
  • Ongoing care: Clinical manifestations, functional limitations, and associated risks of delirium can persist, requiring admission and supportive care.
  • Behavioral emergencies: See “Treatment of agitation in delirium.”

Supportive care [8][10][16]

  • Patient comfort and symptom control
  • Reducing confusion
    • At least three times daily, hospital staff or family should reorient the patient to time, place, and person. [8]
    • Initiate cognitive stimulation therapy to improve cognitive function.
    • See also “Nonpharmacologic prophylaxis” in “Prevention.”
  • Prevention of complications [8]
    • Decubitus ulcers
      • Mobilize hypoactive patients frequently (i.e., every 2 hours).
      • Establish a toilet program to help manage incontinence.
    • Aspiration of food or fluid
      • Elevate the head of the bed.
      • Supervise meals and use assisted feeding techniques.
    • Falls and injuries

A comprehensive care strategy involving multidisciplinary health providers and family members is preferred to prevent and address complications of delirium. [8]

  • Patients with delirium may become agitated or aggressive as a result of acute confusion, particularly in unfamiliar environments.
  • Agitation should initially be managed with nonpharmacologic strategies.
  • Medications should be reserved for refractory agitation.

Nonpharmacological measures

Avoid physical restraints as much as possible in elderly patients with delirium, as they can worsen distress and agitation, as well as contribute to preventable injuries. [18]


  • Sedating medications should be limited to patients with agitation severe enough to pose a risk to themselves or others.
  • To minimize the risk of worsening delirium with medication:
    • Check for drug interactions.
    • Start with the lowest possible dose.
    • Titrate until agitation reduces.
    • Discontinue the drug as soon as possible.
  • Consider specialist consultation (e.g., psychiatry, geriatrics) for patients who need continual dosing.
  • The recommended dosages for older adults are lower than for younger patients. [8][19]

Antipsychotics (first-line) [8][19]

All antipsychotics have sedating properties that may help treat refractory agitation.

Avoid antipsychotics in patients with underlying alcohol withdrawal or benzodiazepine withdrawal (due to the risk of seizures) and in patients at high risk for QTc prolongation (due to the risk of torsades de pointes). [9]

Benzodiazepines (second-line) [8][10][19]

Benzodiazepines are deliriogenic. Do not treat delirious patients with benzodiazepines unless the delirium is due to alcohol or benzodiazepine withdrawal.

  • Over one-third of cases of delirium can be prevented with nonpharmacological strategies. [5]
  • The following measures can reduce morbidity: [20]
    • Early identification of at-risk patients (see “Etiology”)
    • Regular screening to detect early signs of delirium
    • Tailored care according to risk, e.g., validated monitoring tools and prevention strategies for elderly patients [9][10][20]

Elderly patients are at particularly high risk for delirium during hospitalization and benefit from specialized monitoring and prevention. [20]

Prevention strategies

  • Nonpharmacologic prophylaxis
    • Reduce exposure to modifiable risk factors.
      • Avoid drugs that can worsen delirium (e.g., benzodiazepines, anticholinergics, opioids).
      • Avoid restraints if possible.
      • Ensure that the patient is comfortable and that symptoms are well controlled (see “Supportive care” in “Management” section).
    • Reorient the patient regularly.
      • Keep a clock and/or calendar near the patient to help with orientation.
      • Provide visual and hearing aids for patients with impairments.
    • At night, reduce the amount of noise, procedures, and medication administration.
    • Arrange for regular visits from family and friends.
    • Regularly assess at-risk patients using the CAM tool to detect delirium early.
  • Pharmacological prophylaxis: Some medications (e.g., dexmedetomidine, melatonin) have been used to prevent delirium in the critical care/postoperative settings, but benefits are still uncertain. [16]

Uninterrupted sleep is particularly important in patients with delirium, who may experience a worsening of neuropsychiatric symptoms in the evening and at night known as sundowning.

Cholinesterase inhibitors have not been shown to be effective in the prevention or treatment of delirium. However, patients requiring long-term treatment cholinesterase inhibitors can continue to use them. [21][22]

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