August 29, 2020

Delirium (Confusion): An Overview of Acute Confusional State

Delirium (sudden confusion) is a serious disturbance in mental abilities resulting in confused thinking and reduced awareness of the environment. There is rapid decline from previous baseline mental functioning over a short period of time, typically hours to days. Delirium can have many different causes, and often traced to one or more contributing factors, such as changes in metabolic balance (like low sodium). Get medical help immediately if someone suddenly becomes confused (delirious).

Synonyms: acute confusional state, acute brain failure, acute organic reaction, postoperative psychosis

Overview of delirium

Delirium (acute confusional state) is a sudden and severe change in brain function that causes a person to appear confused or disoriented, or to have difficulties maintaining focus, thinking clearly, and remembering recent events, typically with a fluctuating course. Delirium can be triggered by a serious medical illness such as an infection, certain medications, and other causes, such as alcohol or drug withdrawal or intoxication. Older patients, over 65 years, are at highest risk for developing delirium. People with previous brain disease or brain damage are also at risk. Some patients become agitated, while others may be quietly confused.

Delirium is very common in intensive care units and on cancer wards, but can be found on any ward throughout the hospital and in nursing homes and can appear in private homes, especially in high-risk patients (see below).

Delirium is distinct from dementia because it develops suddenly, over hours to days, rather than months to years. And unlike dementia, delirium is usually temporary, resolving when the underlying cause is addressed promptly. Delirium also differs from the psychosis of psychiatric disease, in which orientation, concentration, and attention are usually less impaired. However, these features are not always reliable.

The goal of treatment is to address the cause of delirium when possible and to keep the person safe.

Causes of delirium

It is not clear why or how delirium develops. There are many potential causes, with the most common including infections, medications, and organ failure (such as severe lung or liver disease). The underlying infection or condition is not necessarily a brain problem.

It is not clear why or how delirium develops
As examples:
  • A urinary tract infection or dehydration can cause delirium in certain people.
  • The time after surgery (called the postoperative period) is a common time for delirium to develop, especially in older people. This may be related to pain or the use of anesthesia or pain medications.
  • Sepsis, a life-threatening illness caused by the body's response to severe infection, is often associated with changes in brain function even among people who are young and previously healthy.
Risk factors — Certain underlying conditions increase the risk of delirium:
  • Advanced age
  • Underlying brain diseases such as dementia, stroke, or Parkinson disease, particularly when there are current problems with memory
  • Use of multiple medications (particularly psychiatric drugs and sedatives), or multiple medical problems
  • Sudden withdrawal of a regular medication or cessation of regular alcohol use
  • Frailty, malnutrition, immobility
  • Advanced cancer
  • Undertreated pain (although excessive use of opioid pain medication for pain control can also impair brain function)
  • Immobilization, including physical restraints
  • Use of bladder catheters
  • Limb fractures
  • Interventions, including diagnostic tests
  • Poor eyesight or hearing
  • Sleep deprivation
  • Organ failure (eg, chronic lung disease; heart, kidney, or liver failure)
How common is delirium? — Nearly 30 percent of older patients experience delirium at some time during hospitalization; the incidence is higher in intensive care units. Among older patients who have had surgery, the risk of delirium varies from 10 to greater than 50 percent.

Symptoms of delirium

Delirium is not a disease, but rather a group of symptoms. The key features include:
  • There are abnormal changes in the person's level of consciousness and thinking. The person may be sleepy, or may appear to be withdrawn and depressed (hypoactive delirium) or agitated (hyperactive delirium), or alternate between these states. The changes may be subtle initially.
  • The person often has difficulty maintaining focus. He/she may change the subject frequently in a conversation, have difficulty retaining new information, mention strange ideas, or be disoriented (in place or in time). Some patients have visual hallucinations.
These changes develop over a short period of time (hours to days) and tend to become intermittently worse, especially in the afternoon and evening. This sudden change helps to differentiate delirium from dementia, which worsens slowly over months to years. See the separate article, Dementia (including Alzheimer disease).

Evaluation of delirium

Delirium may be difficult to recognize because changes in behavior may be attributed to the person's age, history of dementia, or other mental disorders. In addition, the symptoms can come and go, such that a person has no or few symptoms early in the day but progressively worsens late in the day or in the evening.

If a caregiver or family member suspects that their relative has delirium, it is important that the person is evaluated promptly by a healthcare expert to identify the underlying cause and begin treatment if possible. Some life-threatening conditions can cause delirium, so it is important to be evaluated quickly. If the person is hospitalized, the evaluation may be done by the attending physician or team. If the person is at home, the patient should see their primary care provider or go to the emergency department. It is critical that clinicians evaluating a person with suspected delirium know the patient's full medical history and all current medications, both prescribed and over-the-counter. If the patient was recently seen at another hospital or clinical, electronic copies of the health record should be requested.

Laboratory testing — Blood and/or urine tests may be performed to determine the cause of the person's delirium. Delirium may be the first manifestation of a severe infection or sepsis, so additional tests to identify infection may be done. A chest x-ray is often required to exclude pneumonia.

Brain imaging tests — If the cause of a person's delirium cannot be determined based upon the history, physical examination, and laboratory testing, a computed tomography (CT) scan or magnetic resonance imaging (MRI) scan of the head may be recommended. This test can help to determine if an abnormal growth, bleeding, infection, or inflammation is present in the brain.

Lumbar puncture — During a lumbar puncture, or spinal tap, a clinician uses a needle to remove a sample of spinal fluid from the area around the spinal cord in the low back. Several tests are done on the fluid to determine if an infection (such as meningitis or encephalitis) could be causing delirium, and if so, which antibiotic treatment is best.

Lumbar puncture is not recommended for every person with delirium. It may be performed if other tests are unable to determine the cause, or if there are other signs of central nervous system infection.

EEG testing — Electroencephalography (EEG) measures the electrical activity in the brain. It may be performed in a person with delirium to search for abnormal electrical activity that is commonly associated with seizures and epilepsy. It is not recommended for all people with delirium, but it may be performed if other tests are unable to determine the cause.

Treatment of delirium

There is no specific treatment for delirium. Instead, treatment focuses on several basic principles:
  • Avoid factors known to cause or aggravate delirium, such as certain medications
  • Identify and treat the underlying illness
  • Provide supportive and restorative care
  • Control dangerous and disruptive behaviors to avoid harm to the patient or others
In people with a first episode of delirium, the initial treatment is often provided in a hospital setting. This allows the health care provider to monitor the patient, begin treatment of the underlying problem, and develop a long-term care plan with the patient and/or family.

Supportive care — The goal of supportive care is to maintain the patient's health, prevent additional complications, and avoid those factors that can aggravate delirium. This includes:
  • Making sure the person gets enough to eat and drink (or providing nutrition through an IV, if needed)
  • Treating pain and avoiding discomfort, including avoiding constipation. See the separate article, Constipation in adults for more details
  • Minimizing the use of restraints and bladder catheters, which can be uncomfortable, particularly to confused patients
  • Encouraging movement (getting out of bed in order to walk) with necessary assistance to avoid falls
  • Having someone help during meals and having the person sit upright to minimize the risk of inhaling food, drinks, and/or saliva, which can lead to pneumonia
  • Maintaining a regular night-day/sleep-wake cycle when possible and avoiding sleep deprivation, and maintaining a reassuring and familiar environment with one or two visiting family members or familiar objects/pictures from home
  • Avoiding overstimulation (eg, multiple visitors, loud noise), which can worsen delirium, but also avoiding understimulation (darkened room, complete silence)
  • Making hearing aids and eyeglasses available at the hospital if the patient uses these at home
Managing behaviors — Some people with delirium have disruptive behaviors, potentially causing them to harm themselves or others. The person may say or do things that are obscene or offensive, but such behaviors do not reflect the person's true beliefs. The person may also be at risk for falling, wandering off, or inadvertently removing intravenous lines.

Sitter — Allowing a family member or other caregiver to stay with the patient at the bedside may help to manage the patient's behavior. This person can provide reassurance, answer questions, reorient the patient, and notify staff if the person needs assistance. In some cases, the hospital is able to provide a sitter if a family member is unavailable. However, a familiar and trusted family member or friend can provide additional reassurance to the patient.

Medications — Medications to control difficult behavior are only to be considered as a last resort, if the patient's agitation is so extreme as to be a potential source of harm. Some classes of drugs, especially sedatives such as lorazepam (Ativan) and diazepam (Valium), can build up in the bloodstream and cause the person to become more confused. Antipsychotic medications, such as haloperidol (Haldol), may be considered, but only in small doses and for short periods of time. If necessary, these medications should be stopped frequently, with direction or approval by the physician, so that the patient can be reevaluated. Antipsychotic medications are not recommended for long-term treatment.

Restraints — The use of restraints (to tie a person to their bed or chair) is almost never appropriate, as restraints can increase agitation and create additional problems by preventing the person from moving around as needed. Preventing movement also potentially allows skin sores (called pressure ulcers) to develop from sitting or lying in the same position for long periods. The use of restraints has not been shown to prevent harmful falls among hospitalized patients.

However, in the rare situation where the patient is at high risk for harm and restraints are applied, hospital staff should monitor the patient at least every two hours, untying the restraints and changing the patient's position. The restraints should be removed as soon as possible.

Recovery from delirium

Delirium has an enormous impact upon the health of older people. Patients with delirium may experience prolonged hospitalizations and a decreased ability to function independently, and are at high risk for requiring care in a long-term care facility (eg, nursing home). This may be the result of underlying conditions, such as mild dementia, that become unmasked or worsen as a result of the acute illness or medications that brought on the delirium. However, even patients with no prior history of brain disorders can require a long period of time to recover from delirium resulting from a severe illness.

Delirium can be frightening for the patient, as well as for the caregiver or family. Caregivers may feel exhausted and frustrated because of the time and other resources required to take care of a person with delirium.

Delirium can sometimes resolve within hours to days. In other cases, it takes weeks or months to fully resolve. For this reason, it is important for caregivers to discuss the patient's short- and long-term needs with a health care provider. Even patients that appear to have recovered from delirium may have trouble remembering medications and self-care instructions. Once the person is released from the hospital, additional assistance from family members or a home health nurse may be needed to assure a safe transition to home. In some cases, a rehabilitation or subacute care facility may be needed until the person has recovered and is able to care for him/herself. If the person is unlikely to be able to care for him/herself again, then ongoing formal home-based services or an assisted living facility or nursing home may be required.

Where to get more information

Your healthcare provider is the best source of information for questions and concerns related to your medical problem.

1). AAFP: Delirium. Available online:
2). Harvard Health: Hospital delirium is common and often goes unrecognized, reports Harvard Women’s Health Watch. Available online:
3). UpToDate: Patient education: Delirium (Beyond the Basics). Available online:
4). Mayo Clinic. Delirium. Available online:

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