Delirium is a mental state that involves an acute change in attention and awareness. It can be the direct effect of a medical condition or related to a substance. It can cause disorganized thinking, inattention, memory loss, and confusion.

Delirium often happens in older adults, especially those hospitalized in the intensive care unit (ICU). It may also occur due to surgery, side effects from medication, seizures, or withdrawal from alcohol and drugs.

Delirium can be preventable. Once it is diagnosed, it is also usually temporary and treatable. Learn more about delirium, including symptoms, types, causes, diagnosis, and treatment.

Hospitalized patient looks confused, may have delirium

SilviaJansen / Getty Images

Symptoms of Delirium

Delirium presents as disturbances in attention, consciousness, and cognition. It may also involve symptoms of psychosis (a break with reality), such as hallucinations. 

The most common symptoms of delirium include:

  • Disorientation
  • Fluctuations in levels of consciousness
  • Problems with memory
  • Changes in thinking and attention span
  • Difficulties with movement and coordination
  • Difficulty concentrating
  • Changes in mood and emotion, such as anger, irritability, and sadness
  • Confusion
  • Excessive sleepiness
  • Incontinence (inability to control urination or defecation)
  • Hallucinations 
  • Illusions
  • Speaking incoherently

The symptoms of delirium often appear abruptly over the course of hours or days. In many but not all cases, people experience delirium while they’re hospitalized for another reason. Healthcare providers or loved ones may be the first to notice the symptoms.

Types of Delirium

There are three main types of delirium, which include:

  • Hyperactive delirium: Hyperactive delirium displays restlessness, irritability, nervousness, and agitation. Aggression may occur in some cases.
  • Hypoactive delirium: People experiencing hypoactive delirium may appear sedated, apathetic, and/or excessively sleepy. They may speak or move more slowly than usual. 
  • Mixed delirium: Mixed delirium involves a combination of hyperactive and hypoactive delirium symptoms. 

Some research suggests that hypoactive delirium is more common than hyperactive delirium. However, it is often overlooked because it is not as outwardly obvious in hospital settings.

How Common Is Delirium?

Delirium tens to be common among older adults, especially in hospital settings. By some estimates, up to 30% of older hospitalized people experience delirium.

Causes of Delirium

There is no single known underlying cause of delirium. However, it often appears while someone is hospitalized for another serious illness or condition. Some of the possible causes of delirium include: 

Delirium is particularly common among people over 65. However, anyone can experience delirium, especially if they are using drugs or alcohol, have recently had surgery, or have a chronic or terminal illness.

What Is Delirium Tremens?

Delirium tremens is a specific type of delirium that usually occurs as a result of severe alcohol withdrawal. Symptoms often occur within a few days after someone has their last drink. They may include irritability, tremors, confusion, sleepiness, mood swings, light sensitivity, disruptions in thinking, and dangerous changes in your vital signs (temperature, breathing rate, pulse, and blood pressure).

Delirium vs. Dementia

Because both conditions often occur in older adults, delirium can sometimes be confused with dementia and vice versa. Someone may have both dementia and delirium at the same time. But it’s important to remember that they are separate conditions and require different kinds of medical attention. 

Delirium and dementia share several signs and symptoms in common, including: 

  • Confusion
  • Listlessness
  • Agitation
  • Apathy
  • Memory loss 
  • Difficulty speaking and understanding language
  • In some cases, hallucinations

However, there are several important differences between delirium and dementia. These include:

  • Onset and duration: Dementia emerges over the course of several months or years. Delirium usually develops relatively suddenly.
  • Consciousness: Dementia does not cause someone to have an altered level of consciousness until its very late stages. Someone who is experiencing delirium may have changes in levels of consciousness rapidly.
  • Illness: Dementia itself is not usually accompanied by any additional symptoms of physical illness. Someone experiencing delirium may have a fever, chills, acute pain, or other signs and symptoms of an underlying physical illness contributing to the delirium.

While dementia may remain relatively stable or get worse over an extended time, delirium is an acute medical illness and requires immediate medical attention.

How to Treat Delirium

The best way to treat delirium involves treating its underlying cause. For example, treating dehydration with intravenous (IV) fluids or a UTI with antibiotics will often resolve the symptoms of delirium. 

Making the person who is experiencing delirium more comfortable in their environment may also help. Healthcare providers might remove unnecessary medical equipment from the room, dim the lights, or explain what’s happening and why in order to cut down on confusion and help the person feel safe.

Physical therapists may be able to help the person move around more comfortably, while an occupational therapist may help with mental exercises to improve memory and thinking.

In certain cases, medication may be necessary to treat the symptoms of delirium. Antipsychotic medication, for example, might be prescribed if someone is experiencing disturbing hallucinations.

However, antipsychotic medication needs to be used cautiously when treating delirium, especially for people with dementia, because of possible side effects.

Complications and Risk Factors Associated With Delirium

There are a number of factors that put someone more at risk of developing delirium. Risk factors include:

  • Being over 65 years old
  • Chronic or terminal illness
  • Hearing or vision loss
  • Previous history of delirium
  • Taking three or more prescribed medications
  • Dementia
  • Depression
  • Using an indwelling catheter (a flexible tube to allow urine to drain from the bladder)

If not prevented or treated, delirium is associated with several health complications and other negative outcomes. The complications of delirium may include:

  • Infections
  • Skin problems, such as pressure sores
  • Cognitive decline, including dementia
  • Extended hospital stay
  • Need for long-term institutional care
  • Higher medical costs
  • Lowered quality of life
  • Emotional distress, both for the person and their loved ones
  • Higher risk of death, both in the short-term and long-term

If you or your loved one may have delirium, it’s important to assess and treat it right away to avoid future complications.

Are There Tests to Diagnose the Cause of Delirium?

If you are experiencing signs of delirium, a healthcare provider may be able to make a diagnosis using close observation and simple tests to assess your awareness, thinking, and attention. For example, they may ask you to do some basic math, describe your surroundings, or spell a word.

To determine the underlying cause of your symptoms, a healthcare provider may perform additional tests. These may include urine tests, brain scans, chest X-rays, blood tests, psychological tests, physical exams, and more.

Misdiagnosis of Delirium

Some estimates suggest that up to two-thirds of cases of delirium in hospital settings are missed or misdiagnosed. Signs of delirium may sometimes be confused with symptoms of dementia, depression, or fatigue.

When to See a Healthcare Provider

If you notice any signs of delirium in yourself or a loved one, seek immediate medical care. Stay with the person until help has arrived, and make a note of what medications they’re taking if possible. Reassure them that you’re by their side and help them stay relaxed.

Healthcare providers can help prevent some delirium cases by taking certain preventive steps. Recent estimates suggest that between 30% to 40% of cases are preventable.

If your loved one is hospitalized and you’re concerned about delirium, ask your healthcare provider about taking the following measures:

  • Avoiding social isolation
  • Avoiding restraints
  • Providing social cues to help the person understand where they are and what’s happening
  • Making sure the person is resting in a comfortable, quiet, and well-lit room
  • Ensuring that they are well-fed and hydrated
  • Preventing infections and skin breakdown 
  • Promoting movement and mobility 
  • Controlling pain
  • Avoiding sedatives if possible
  • Performing cognitive assessments

When you or your loved one is discharged from the hospital, talk to your healthcare provider about follow-up care and develop a plan to avoid delirium at home. Make sure that you know about any possible side effects of prescribed medicines.


Delirium is an acutely altered mental state that causes confusion, disordered thinking, memory issues, and inattention. It may also cause waxing and waning levels of consciousness, disorientation, hallucinations, illusions, and changes in speech or movement. It is usually preventable, treatable, and temporary. It is often missed or misdiagnosed. 

Delirium is especially common in older adults who are hospitalized, particularly in the intensive care unit (ICU). Common causes of delirium include severe illness, infection, alcohol intoxication, withdrawal from drugs, dehydration, electrolyte imbalances, and recent surgery.

Treatment for delirium usually involves treating the underlying cause, such as the infection or dehydration, and making the person feel safe and comfortable. In certain cases, it may require antipsychotic medication.

A Word From Verywell

If you or a loved one is experiencing possible signs of delirium, such as confusion or disorientation, tell a healthcare provider right away. Delirium is often both treatable and temporary, but it needs to be addressed as soon as possible.

Frequently Asked Questions

  • How long does delirium last?

    Delirium is often short-lived and temporary. Symptoms of delirium usually appear over the course of a few hours or days. After treatment, delirium usually goes away within a few days or weeks.

  • What causes delirium?

    There are several possible causes of delirium. Many people who experience delirium are over 65 and hospitalized for another condition, such as an infection, dehydration, dementia, or serious illness like kidney failure. Other causes of delirium include recent major surgery and withdrawal from medication, alcohol, or drugs.

  • Why is delirium dangerous?

    Delirium is dangerous because it can lead to a variety of negative outcomes if left untreated. Untreated delirium significantly increases the risk of death within the next two years.

    It can also lead to complications like cognitive decline, infections, skin problems, and loss of motor function and mobility, in addition to raising the risk of institutionalization and causing emotional distress for both the person and their loved ones.

17 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Psychological Association. Delirium.

  2. MedlinePlus. Delirium.

  3. American Psychological Association. Psychosis.

  4. van Velthuijsen EL, Zwakhalen SM, Mulder WJ, Verhey FR, Kempen GI. Detection and management of hyperactive and hypoactive delirium in older patients during hospitalization: a retrospective cohort study evaluating daily practiceInt J Geriatr Psychiatry. 2018;33(11):1521-1529. doi:10.1002/gps.4690

  5. Johansson YA, Bergh I, Ericsson I, Sarenmalm EK. Delirium in older hospitalized patients-signs and actions: a retrospective patient record reviewBMC Geriatr. 2018;18(1):43. doi:10.1186/s12877-018-0731-5

  6. Royal College of Psychiatrists. Delirium.

  7. MedlinePlus. Delirium tremens.

  8. American Geriatrics Society. Delirium diagnosis and tests.

  9. Memorial Sloan Kettering Cancer Center. Caring for someone with delirium.

  10. American Geriatrics Society. Delirium care and treatment.

  11. Alzheimer's Society. Delirium.

  12. Agency for Clinical Innovation. Care of confused hospitalized older persons.

  13. Grover S, Avasthi A. Clinical practice guidelines for management of delirium in elderlyIndian J Psychiatry. 2018;60(Suppl 3):S329-S340. doi:10.4103/0019-5545.224473

  14. NHS. Sudden confusion (delirium).

  15. Ghaeli P, Shahhatami F, Mojtahed Zade M, Mohammadi M, Arbabi M. Preventive intervention to prevent delirium in patients hospitalized in intensive care unitIran J Psychiatry. 2018;13(2):142-147. PMID: 29997660

  16. Today's Hospitalist. Seven strategies to help you manage or prevent delirium.

  17. Lauretani F, Bellelli G, Pelà G, Morganti S, Tagliaferri S, Maggio M. Treatment of delirium in older persons: what we should not do!Int J Mol Sci. 2020;21(7):2397. doi:10.3390/ijms21072397

By Laura Dorwart
Laura Dorwart is a health journalist with particular interests in mental health, pregnancy-related conditions, and disability rights. She has published work in VICE, SELF, The New York Times, The Guardian, The Week, HuffPost, BuzzFeed Reader, Catapult, Pacific Standard,, Insider,, TalkPoverty, and many other outlets.