(redirected from deliriums)
Also found in: Dictionary, Thesaurus, Legal, Encyclopedia.




Delirium is a state of mental confusion that develops quickly and usually fluctuates in intensity.


Delirium is a syndrome, or group of symptoms, caused by a disturbance in the normal functioning of the brain. The delirious patient has a reduced awareness of and responsiveness to the environment, which may be manifested as disorientation, incoherence, and memory disturbance. Delirium is often marked by hallucinations, delusions, and a dream-like state.
Delirium affects at least one in 10 hospitalized patients, and is a common part of many terminal illnesses. Delirium is more common in the elderly than in the general population. While it is not a specific disease itself, patients with delirium usually fare worse than those with the same illness who do not have delirium.

Causes and symptoms


There are a large number of possible causes of delirium. Metabolic disorders are the single most common cause, accounting for 20-40% of all cases. This type of delirium, termed "metabolic encephalopathy," may result from organ failure, including liver or kidney failure. Other metabolic causes include diabetes mellitus, hyperthyroidism and hypothyroidism, vitamin deficiencies, and imbalances of fluids and electrolytes in the blood. Severe dehydration can also cause delirium.
Drug intoxication ("intoxication confusional state") is responsible for up to 20% of delirium cases, either from side effects, overdose, or deliberate ingestion of a mind-altering substance. Medicinal drugs with delirium as a possible side effect or result of overdose include:
  • anticholinergics, including atropine, scopolamine, chlorpromazine (an antipsychotic), and diphenhydramine (an antihistamine)
  • sedatives, including barbiturates, benzodiazepines, and ethanol (drinking alcohol)
  • antidepressant drugs
  • anticonvulsant drugs
  • nonsteroidal anti-inflammatory drugs (NSAIDs), including ibuprofen and acetaminophen
  • corticosteroids, including prednisone
  • anticancer drugs, including methotrexate and procarbazine
  • lithium
  • cimetidine
  • antibiotics
  • L-dopa
Delirium may result from ingestion of legal or illegal psychoactive drugs, including:
  • ethanol (drinking alcohol)
  • marijuana
  • LSD (lysergic acid diethylamide) and other hallucinogens
  • amphetamines
  • cocaine
  • opiates, including heroin and morphine
  • PCP (phencyclidine)
  • inhalants
Drug withdrawal may also cause delirium. Delirium tremens, or "DTs," may occur during alcohol withdrawal after prolonged or intense consumption. Withdrawal symptoms are also possible from many of the psychoactive prescription drugs.
Poisons may cause delirium ("toxic encephalopathy"), including:
  • solvents, such as gasoline, kerosene, turpentine, benzene, and alcohols
  • carbon monoxide
  • refrigerants (Freon)
  • heavy metals, such as lead, mercury, and arsenic
  • insecticides, such as Parathion and Sevin
  • mushrooms, such as Amanita species
  • plants such as jimsonweed (Datura stramonium) and morning glory (Ipomoea spp.)
  • animal venoms
Other causes of delirium include:
  • infection
  • fever
  • head trauma
  • epilepsy
  • brain hemorrhage or infarction
  • brain tumor
  • low blood oxygen (hypoxemia)
  • high blood carbon dioxide (hypercapnia)
  • post-surgical complication


The symptoms of delirium come on quickly, in hours or days, in contrast to those of dementia, which develop much more slowly. Delirium symptoms typically fluctuate through the day, with periods of relative calm and lucidity alternating with periods of florid delirium. The hallmark of delirium is a fluctuating level of consciousness. Symptoms may include:
  • decreased awareness of the environment
  • confusion or disorientation, especially of time
  • memory impairment, especially of recent events
  • hallucinations
  • illusions and misinterpreted stimuli
  • increased or decreased activity level
  • mood disturbance, possibly including anxiety, euphoria or depression
  • language or speech impairment


Delirium is diagnosed through the medical history and recognition of symptoms during mental status examination. The most important part of diagnosis is determining the cause of the delirium. Tests may include blood and urine analysis for levels of drugs, fluids, electrolytes, and blood gases, and to test for infection; lumbar puncture ("spinal tap") to test for central nervous system infection; x ray, computed tomography scans (CT), or magnetic resonance imaging (MRI) scans to look for tumors, hemorrhage, or other brain abnormality; thyroid tests; electroencephalography (EEG); electrocardiography (ECG); and possibly others as dictated by the likely cause.


Treatment of delirium begins with recognizing and treating the underlying cause. Delirium itself is managed by reducing disturbing stimuli, or providing soothing ones; use of simple, clear language in communication; and reassurance, especially from family members. Physical restraints may be needed if the patient is a danger to himself or others, or if he insists on removing necessary medical equipment such as intravenous lines or monitors. Sedatives or antipsychotic drugs may be used to reduce anxiety, hallucinations, and delusions.


Persons with delirium usually have a worse prognosis for the underlying disease than the person without delirium. Nonetheless, those without terminal illness usually recover from delirium. They may not, however, regain all their original cognitive abilities, and may be left with some permanent impairments, including fatigue, irritability, difficulty concentrating, or mood changes.


Prevention of delirium is focused on treating or avoiding its underlying causes. The most preventable forms are those induced by drugs. Strategies for reducing delirium include following prescriptions, consulting the prescribing physician immediately if symptoms occur, and consulting the physician before discontinuing the drug, even if it has been ineffective; avoiding intoxication with legal or illegal drugs, and seeking professional assistance before suddenly discontinuing an addictive drug such as alcohol or heroin; maintaining good nutrition, which promotes general health and can minimize the likelihood of delirium from alcohol intoxication and withdrawal; and avoiding exposure to solvents, insecticides, heavy metals, or biological poisons in the home or workplace.



Guze, Samuel, editor. Adult Psychiatry. Mosby Year Book, 1997.

Key terms

Dementia — A loss of mental ability severe enough to interfere with functioning. While dementia and delirium have some of the same symptoms, dementia has a much slower onset.
Electroencephalogram (EEG) — A chart of the brain wave patterns picked up by electrodes placed on the scalp. This is useful for diagnosing central nervous system disorders.
Encephalopathy — A brain dysfunction or disorder.


 [dĕ-lēr´e-um] (pl. deli´ria)
An acute, transient disturbance of consciousness accompanied by a change in cognition and having a fluctuating course. Characteristics include reduced ability to maintain attention to external stimuli and disorganized thinking as manifested by rambling, irrelevant, or incoherent speech; there may also be a reduced level of consciousness, sensory misperceptions, disturbance of the sleep-wakefulness cycle and level of psychomotor activity, disorientation to time, place, or person, and memory impairment. Delirium may be caused by a number of conditions that result in derangement of cerebral metabolism, including systemic infection, cerebral tumor, poisoning, drug intoxication or withdrawal, seizures or head trauma, and metabolic disturbances such as fluid, electrolyte, or acid-base imbalance, hypoxia, hypoglycemia, or hepatic or renal failure.
alcohol withdrawal delirium (delirium tre´mens) an acute alcohol withdrawal syndrome that can occur in any person who has a history of drinking heavily and suddenly stops. It can occur with any form of alcoholic beverage, including beer and wine, and is most commonly seen in chronic alcoholics. The severity of the symptoms usually depends on the length of time the patient has had a problem of alcohol abuse and the amount of alcohol that had been drunk before the abstinence that precipitated the delirium. See also alcoholism.
Clinical Course. Generally, this syndrome begins a few days after drinking has ceased and ends within 1–5 days. It can be heralded by a variety of signs and symptoms. Some patients exhibit only mild tremulousness, irritability, difficulty in sleeping, an elevated pulse rate and hypertension, and increased temperature. Others have generalized convulsions as the first sign of difficulty. Most persons exhibit severe memory disturbance, agitation, anorexia, and hallucinations.

Hallucinations are likely to follow the early signs and usually, but not always, are unpleasant and threatening to the patient. These hallucinations can be of three types: auditory, visual, or tactile. Delusions often follow or accompany the hallucinations. These patients are unable to think clearly and sometimes become paranoid and greatly agitated. At this point they can become dangerous to themselves and others.

Generalized grand mal seizures can occur in delirium tremens. The hallucinations and delusions may continue, contributing to the state of agitation and precipitating seizures.
Treatment and Patient Care. Persons with delirium tremens are very ill and have multiple short-term and long-term problems. They should be kept in a quiet, nonstimulating environment and approached in a calm, reassuring manner. They must be watched closely and protected from self-injury during the period of delirium and also when they are convalescing from their illness and are likely to feel great remorse and depression. They should be observed for signs of extreme fatigue, pneumonia, or heart failure. Respiratory infections are quite common in these patients because of their weakened condition and inattention to personal hygiene.

The diet should be high in fluid intake and carbohydrate content and low in fats. If the patient has cirrhosis, protein intake may be limited. Dietary supplements usually include vitamin preparations, especially the B complex vitamins. If the patient is unable to cooperate by taking fluids and food by mouth, tube feeding and intravenous fluids may be necessary. Tranquilizing agents and sedatives are useful for therapy.


, pl.


(dĕ-lir'ē-ŭm, dĕ-lir'ē-ă),
An altered state of consciousness, consisting of confusion, distractibility, disorientation, disordered thinking and memory, defective perception (illusions and hallucinations), prominent hyperactivity, agitation, and autonomic nervous system overactivity; caused by illness, medication, or toxic, structural, and metabolic disorders.
[L. fr. deliro, to be crazy, fr. de- + lira, a furrow (i.e., go out of the furrow)]


/de·lir·i·um/ (dĕ-lēr´e-um) pl. deli´ria   a mental disturbance of relatively short duration usually reflecting a toxic state, marked by illusions, hallucinations, delusions, excitement, restlessness, impaired memory, and incoherence.
alcohol withdrawal delirium  that caused by cessation or reduction in alcohol consumption, typically in alcoholics with many years of heavy drinking, characterized by autonomic hyperactivity, such as tachycardia, sweating, and hypertension, a coarse, irregular tremor, and delusions, vivid hallucinations, and wild, agitated behavior.
delirium tre´mens  alcohol withdrawal d.


n. pl. delir·iums or delir·ia (-ē-ə)
A temporary state of mental confusion and fluctuating consciousness resulting from high fever, intoxication, shock, or other causes. It is characterized by anxiety, disorientation, hallucinations, delusions, and incoherent speech.

de·lir′i·ant adj.


Etymology: L, delirare, to rave
1 a state of frenzied excitement or wild enthusiasm.
2 an acute organic mental disorder characterized by confusion, disorientation, restlessness, clouding of the consciousness, incoherence, fear, anxiety, excitement, and, often, illusions; hallucinations, usually of visual origin; and, at times, delusions. The condition is caused by disturbances in cerebral functions that may result from a wide range of metabolic disorders, including nutritional deficiencies and endocrine imbalances; postpartum or postoperative stress; ingestion of toxic substances, such as various gases, metals, or drugs, including alcohol; and other causes of physical and mental shock or exhaustion. The symptoms are usually of short duration and reversible with treatment of the underlying cause; in extreme cases, however, in which the toxic condition is exceedingly severe or prolonged, permanent brain damage may occur. Kinds of delirium include acute delirium, chronic delirium, delirium tremens, exhaustion delirium, senile delirium, and traumatic delirium. Compare dementia. delirious, adj.
observations There is a rapid onset and acute change in mentation. Manifestations include fluctuating levels of consciousness; disorientation; impaired memory; inability to maintain or shift attention; irritability, agitation, restlessness, and hyperactivity; perceptual disturbance, hallucinations, and delusions; rambling and fragmented speech; and impaired sleep-wake cycle. There are typically lucid intervals with symptoms worsening at night. Duration of symptoms is limited. There are four DSM-IV diagnostic criteria for delirium: (1) disturbance of consciousness with reduced awareness and diminished abilities to focus and to maintain or shift attention; (2) a change in cognition, such as disorientation, memory loss, or language disturbance; (3) the development of the disturbance over a period of hours to days, with fluctuation during the day; and (4) evidence from clinical exam and/or lab findings that the disturbance is caused by physiological consequences of a medical condition. Delirium places medically ill individuals at greater risk for medical complications (pneumonia and decubitus) and is associated with functional decline and institutional placement. Delirium may lead to dementia.
interventions Intervention centers around removal or withdrawal from toxic agents (alcohol and barbiturates) and IV sedation with antianxiety and antipsychotic agents for agitation, seizure activity, and tremors. Adequate fluid and electrolyte balance is also crucial.
nursing considerations Nursing care during an acute episode of delirium is aimed at support, reduction of confusion and agitated behavior, and prevention of injury. Interventions include seizure precautions, safety precautions (e.g., prevent wandering and climbing over bedrails), environmental control (adequate lighting, noise reduction, clear space, removal of hazards, avoidance of sensory extremes, and allowance for adequate sleep), reorientation procedures (e.g., clocks, calendars, familiar objects, use of glasses and hearing aids), consistency of caretakers, and family involvement. Restraints should be avoided. Tactics to prevent delirium are crucial in susceptible individuals (e.g., those with chronic or mental illness, altered sensory perception, or neurological disease; those with elevated ammonia, increased blood urea nitrogen, or hypoxia; those on CNS stimulants or depressants), and those in altered environments (e.g., ICU, isolation, incubators, and institutions). This is accomplished by assessing and removing noxious environmental stimuli while increasing meaningful stimuli. Reduction of risk factors (e.g., sleep deprivation, visual or hearing impediments, adverse medications, dehydration, and pain) and use of orienting features (e.g., clocks, calendars, windows, and familiar objects) are important, as is maintaining verbal and nonverbal contact, with judicious use of touch. Structuring and explaining routines and procedures and interpreting sights, sounds, and smells in the environment are also crucial in preventing delirium.


Neurology An acute organic brain disorder caused by a defect in cognate functions with global impairment and a ↓ clarity of awareness of the environment, which may progress or regress Etiology May be multifactorial–eg, due to toxins; substance abuse; acute psychosis, medication–eg anticholinergics; anemia, brain lesions–eg 1º tumors or metastases; chemotherapy–eg, MTX, corticosteroids, asparginase, vincristine; endocrinopathies–eg, hypoglycemia; fever; infection; metabolic derangement–eg, ↑ Ca2+, ↓ Na+ paraneoplastic syndromes Clinical Disturbance of sleep-wake cycle, with insomnia and/or daytime drowsiness, altered psychomotor activity, perceptual disturbances, and behavior changes–eg anger, anxiety, depression, fear, irritability, paranoia, withdrawal, most prominent at night Diagnosis EEG–slowing of brain waves; cognitive capacity screening examination; mini-mental state test; trail-making B test. See Black patch delirium, Fatal excited delirium, Pseudodelirium. Cf Dementia.


, pl. deliria (dĕ-lir'ē-ŭm, -ă)
An altered state of consciousness, consisting of confusion, distractibility, disorientation, disordered thinking and memory, defective perception (illusions and hallucinations), prominent hyperactivity, agitation, and autonomic nervous system overactivity; caused by a number of toxic structural and metabolic disorders.
[L. fr. deliro, to be crazy]


A mental disturbance from disorder of brain function caused by high fever, head injury, drug intoxication, drug overdosage or drug withdrawal. There is confusion, disorientation, restlessness, trembling, fearfulness, DELUSION and disorder of sensation (HALLUCINATION). Occasionally there is maniacal excitement.


acute confusional state secondary to systemic pathology (e.g. infection, pyrexia, chronic long-term hypothyroidism, marked vitamin B12 deficiency, chronic alcoholism) or induced by pharmacological agents (e.g. nitrazepam, carbidopa and benhexol); common in elderly patients with psychiatric illnesses; Box 1
Box 1: Characteristics noted in patients with delirium
  • Loss of ability to undertake sustained mental activity

  • Fluctuating levels of consciousness

  • Loss of concentration

  • Disorientation

  • Muscular excitability and twitching

  • Misinterpretation of surroundings and people's intention or action

  • Feelings of fear and persecution


, pl. deliria (dĕ-lir'ē-ŭm, dĕ-lirē-ŭm, -ă)
An altered state of consciousness, consisting of confusion, distractibility, disorientation, disordered thinking and memory and other signs; caused by illness, medication, or toxic, structural, and metabolic disorders.
[L. fr. deliro, to be crazy]

delirium (delir´ēəm),

n a condition of mental excitement, confusion, and clouded sensorium, usually accompanied by hallucinations, illusions, and delusions; precipitated by toxic factors in diseases or drugs.
delirium tremens (DT),
References in periodicals archive ?
As people have begun to better understand the human and financial costs of delirium, attention has turned to preventing and effectively managing it, says Schell-Chaple.
When I began nursing, no one even used the term delirium, and many nurses and physicians still think only about confusion and agitation, says clinical nurse specialist Charlotte Garwood (MS 10), who worked closely with Schell-Chaple in the UCSF ICU for many years and whose masters work included a project on ICU delirium.
If youre not doing standardized screening, delirium could be characterized as something else, says clinical nurse specialist (CNS) Melissa Lee (MS 03).
Delirium is a short term disturbance of consciousness which lasts for as little as a few hours to as much as a few months (Marcantonio et al 2003; Inouye et al 1999b).
Many studies have examined the prevalence of delirium in the acute inpatient setting.
While many people who develop delirium have a pre-existing dementia, delirium is often not detected or is misdiagnosed as dementia or other psychiatric illness even though there are potential strategies to differentiate between dementia and delirium (Cole 2004).
As has been observed by Inouye et al (2001) that hyperactive forms of delirium were more likely to be diagnosed than those with a presentation suggestive of a hypoactive delirium.
Despite the presence in Australia of evidence based guidelines and algorithms (AHMAC 2006) to assist in the diagnosis of delirium the reality is that in the busy hospital environment the imperative is rapid processing of people to facilitate minimum wait times and meet capacity targets (Bezzant 2008).
A cardinal difference for sundowning when contrasted with delirium will be that delirium tends to be relatively brief (a matter of hours or days) and furthermore although delirium may fluctuate during the course of the day it will not share the marked onset and exacerbation instigated by changes brought on by late afternoon or early evening hours.
In the case of the demented patient, the dementia does not preclude the possibility for delirium but may in fact be a pre-condition for nocturnal delirium to take place(2).
As has been noted above, central to the concept of sundowning and what, in fact, in the treatment of this syndrome will differentiate one's intervention in response to other forms of delirium is its onset with diminished light.
A psychiatric consultation should be considered to explore pharmacological interventions once over-medication as the precipitant to the patient's delirium has been ruled out.