Delirium is a serious change in mental abilities. It results in confused thinking and a lack of awareness of someone's surroundings. The disorder usually comes on fast — within hours or a few days.

Delirium can often be traced to one or more factors. Factors may include a severe or long illness or an imbalance in the body, such as low sodium. The disorder also may be caused by certain medicines, infection, surgery, or alcohol or drug use or withdrawal.

Symptoms of delirium are sometimes confused with symptoms of dementia. Health care providers may rely on input from a family member or caregiver to diagnose the disorder.

Symptoms of delirium usually begin over a few hours or a few days. They typically occur with a medical problem. Symptoms often come and go during the day. There may be periods of no symptoms. Symptoms tend to be worse at night when it's dark and things look less familiar. They also tend to be worse in settings that aren't familiar, such as in a hospital.

Primary symptoms include the following.

Reduced awareness of surroundings

This may result in:

• Trouble focusing on a topic or changing topics
• Getting stuck on an idea rather than responding to questions
• Being easily distracted
• Being withdrawn, with little or no activity or little response to surroundings

Poor thinking skills

This may appear as:

• Poor memory, such as forgetting recent events
• Not knowing where they are or who they are
• Trouble with speech or recalling words
• Rambling or nonsense speech
• Trouble understanding speech
• Trouble reading or writing

Behavior and emotional changes

These may include:

• Anxiety, fear or distrust of others
• Depression
• A short temper or anger
• A sense of feeling elated
• Lack of interest and emotion
• Quick changes in mood
• Personality changes
• Seeing things that others don't see
• Being restless, anxious or combative
• Calling out, moaning or making other sounds
• Being quiet and withdrawn — especially in older adults
• Slowed movement or being sluggish
• Changes in sleep habits
• A switched night-day sleep-wake cycle

Types of delirium

Experts have identified three types:

• Hyperactive delirium. This may be the easiest type to recognize. People with this type may be restless and pace the room. They also may be anxious, have rapid mood swings or see things that aren't there. People with this type often resist care.
• Hypoactive delirium. People with this type may be inactive or have reduced activity. They tend to be sluggish or drowsy. They might seem to be in a daze. They don't interact with family or others.
• Mixed delirium. Symptoms involve both types of delirium. The person may quickly switch back and forth from being restless and sluggish.

Delirium and dementia

Delirium and dementia may be hard to tell apart, and a person may have both. Someone with dementia has a gradual decline of memory and other thinking skills due to damage or loss of brain cells. The most common cause of dementia is Alzheimer's disease, which comes on slowly over months or years.

Delirium often occurs in people with dementia. However, episodes of delirium don't always mean a person has dementia. Tests for dementia shouldn't be done during a delirium episode because the results could be misleading.

Some differences between the symptoms of delirium and dementia include:

• Onset. The onset of delirium occurs within a short time — within a day or two. Dementia usually begins with minor symptoms that get worse over time.
• Attention. The ability to stay focused or maintain focus is impaired with delirium. A person in the early stages of dementia remains generally alert. Someone with dementia often isn't sluggish or agitated.
• Rapid changes in symptoms. Delirium symptoms can come and go several times during the day. While people with dementia have better and worse times of day, their memory and thinking skills typically stay at a constant level.

When to see a doctor

If a relative, friend or someone in your care shows symptoms of delirium, talk to the person's health care provider. Your input about symptoms, typical thinking and usual abilities will be important for a diagnosis. It also can help the provider find the cause of the disorder.

If you notice symptoms in someone in the hospital or nursing home, report your concerns to the nursing staff or health care provider. The symptoms may not have been observed. Older people who are in the hospital or are living in a long-term care center are at risk of delirium.

Delirium occurs when signals in the brain aren't sent and received properly.

The disorder may have a single cause or more than one cause. For example, a medical condition combined with the side effects of a medicine could cause delirium. Sometimes no cause can be found. Possible causes include:

• Certain medicines or medicine side effects
• Alcohol or drug use or withdrawal
• A medical condition such as a stroke, heart attack, worsening lung or liver disease, or an injury from a fall
• An imbalance in the body, such as low sodium or low calcium
• Severe, long-lasting illness or an illness that will lead to death
• Fever and a new infection, particularly in children
• Urinary tract infection, pneumonia, the flu or COVID-19, especially in older adults
• Exposure to a toxin, such as carbon monoxide, cyanide or other poisons
• Poor nutrition or a loss of too much body fluid
• Lack of sleep or severe emotional distress
• Pain
• Surgery or another medical procedure that requires being put in a sleep-like state

Some medicines taken alone or taken in combination can trigger delirium. These include medicines that treat:

• Pain
• Sleep problems
• Mood disorders, such as anxiety and depression
• Allergies
• Asthma
• Swelling
• Parkinson's disease
• Spasms or convulsions

Any condition that results in a hospital stay increases the risk of delirium. This is mostly true when someone is recovering from surgery or is put in intensive care. Delirium is more common in older adults and in people who live in nursing homes.

Examples of other conditions that may increase the risk of delirium include:

• Brain disorders such as dementia, stroke or Parkinson's disease
• Past delirium episodes
• Vision or hearing loss
• Multiple medical problems

Delirium may last only a few hours or as long as several weeks or months. If the causes are addressed, the recovery time is often shorter.

Recovery depends to some extent on the health and mental status before symptoms began. People with dementia, for example, may experience an overall decline in memory and thinking skills after a delirium episode. People in better health are more likely to fully recover.

People with other serious, long-lasting or terminal illnesses may not regain the thinking skills or function that they had before the onset of delirium. Delirium in seriously ill people is more likely to lead to:

• A general decline in health
• Poor recovery from surgery
• The need for long-term care
• An increased risk of death

The best way to prevent delirium is to target risk factors that might trigger an episode. Hospital settings present a special challenge. Hospital stays often involve room changes, invasive procedures, loud noises and poor lighting. Lack of natural light and lack of sleep can make confusion worse.

Some steps can help prevent or reduce the severity of delirium. To do this, promote good sleep habits, help the person remain calm and well-oriented, and help prevent medical problems or other complications. Also avoid medicines used for sleep, such as diphenhydramine (Benadryl Allergy, Unisom, others).

A health care provider can diagnose delirium based on medical history and tests of mental status. The provider also will consider factors that may have caused the disorder. An exam may include:

• Medical history. The provider will ask what changed in the last few days. Is there a new infection? Did the person begin a new medicine? Was there an injury or new pain such as chest pain? Did headaches or weakness occur? Did the person use alcohol or a legal or illegal drug?
• Mental status review. The provider starts by testing awareness, attention and thinking. This may be done by talking with the person. Or it may be done with tests or screenings. Information from family members or caregivers can be helpful.
• Physical and neurological exams. A physical exam checks for signs of health problems or disease. A neurological exam checks vision, balance, coordination and reflexes. This can help determine if a stroke or another disease is causing the delirium.
• Other tests. The health care provider may order blood, urine and other tests. Brain-imaging tests may be used when a diagnosis can't be made with other information.

The first goal of delirium treatment is to address any causes or triggers. That may include stopping certain medicines, treating an infection or treating an imbalance in the body. Treatment then focuses on creating the best setting for healing the body and calming the brain.

Supportive care

Supportive care aims to prevent complications. Here are steps to take:

• Protect the airway
• Provide fluids and nutrition
• Assist with movement
• Treat pain
• Address a lack of bladder control
• Avoid the use of physical restraints and bladder tubes
• Avoid changes in surroundings and caregivers when possible
• Include family members or familiar people in care

Medications

If you're a family member or caregiver of someone who has delirium, talk with the health care provider about medicines that may trigger the symptoms. The provider may suggest that the person avoid taking those medicines or that a lower dose is given. Certain medicines may be needed to control pain that's causing delirium.

Other types of medicines may help calm a person who is agitated or confused. Or medicines may be needed if the person is showing distrust of others, is fearful or is seeing things that others don't see. These medicines may be needed when symptoms:

• Make it hard to perform a medical exam or provide treatment
• Put the person in danger or threaten the safety of others
• Don't lessen with other treatments

When symptoms resolve, the medicines are usually stopped or are given in lower doses.

If you're a relative or caregiver of someone who is at risk of delirium, you can take steps to prevent an episode. If you take care of someone who is recovering from delirium, these steps can help improve the person's health and prevent another episode.

Promote good sleep habits

To promote good sleep habits:

• Provide a calm, quiet setting
• Use inside lighting that reflects the time of day
• Help the person keep a regular daytime schedule
• Encourage self-care and activity during the day
• Allow for restful sleep at night

Promote calmness and orientation

To help the person remain calm and aware of their surroundings:

• Provide a clock and calendar and refer to them during the day
• Communicate simply about any change in activity, such as time for lunch or time for bed
• Keep familiar and favorite objects and pictures around, but avoid a cluttered space
• Approach the person calmly
• Identify yourself or other people
• Avoid arguments
• Use comfort measures, such as touch, if they help
• Reduce noise levels and other distractions
• Provide eyeglasses and hearing aids

Prevent complicating problems

To help prevent medical problems:

• Give the person the proper medicines on schedule
• Provide plenty of fluids and a healthy diet
• Encourage regular physical activity
• Get prompt treatment for potential problems, such as infections

Caring for the caregiver

Caring for a person with delirium can be scary and exhausting. Take care of yourself too.

• Consider joining a support group for caregivers.
• Learn more about the condition.
• Ask for pamphlets or other resources from a health care provider, nonprofit organizations, community health services or government agencies.
• Share caregiving with family and friends who are familiar to the person so you get a break.

Organizations that may provide helpful information include the Caregiver Action Network and the National Institute on Aging.

If you're the relative or primary caregiver of a person with delirium, you'll likely play a role in making an appointment or providing information to the health care provider. Here's some information to help you get ready for the appointment and know what to expect.

What you can do

Before the appointment, make a list of:

• All medicines the person takes. That includes all prescriptions, medicines available without a prescription and supplements. Include the doses and note any recent medicine changes.
• Names and contact information of any person who provides care for the person with delirium.
• The symptoms and when they started. Describe all symptoms and any changes in behavior that began before the delirium symptoms. They might include pain, fever or coughing.
• Questions you want to ask the care provider.

What to expect from the doctor

A health care provider is likely to ask several questions about the person with delirium. These may include:

• What are the symptoms and when did they begin?
• Is there or was there a recent fever, cough, urinary tract infection or sign of pain?
• Was there a recent head injury or other trauma?
• What were the person's memory and other thinking skills like before the symptoms started?
• How well did the person perform everyday activities before the onset of symptoms?
• Can the person usually function independently?
• What other medical conditions have been diagnosed?
• Are prescription medicines taken as directed? When did the person take the most recent dose of each?
• Are there any new medicines?
• Do you know if the person recently used drugs or alcohol? Does the person have a history of alcohol or drug misuse? Is there any change in the pattern of use, such as increasing or stopping use?
• Has the person recently appeared depressed, extremely sad or withdrawn?
• Has the person shown signs of not feeling safe?
• Are there any signs of paranoia?
• Has the person seen or heard things that no one else does?
• Are there any new physical symptoms — for example, chest or stomach pain?

The provider may ask additional questions based on your responses and the person's symptoms and needs. Preparing for these questions helps you make the most of your time with a provider.