Was this helpful?

What are hallucinations?

Hallucinations are sensations or perceptions that occur in a wakeful state and seem real, but are created by the brain. Hallucinations may be seen, heard, smelled, felt or tasted. They can be pleasant or threatening and may be related to sensations, imagery, or events of the past, or they may be unrelated to experiences. Common hallucinations include hearing voices; seeing objects, lights or people who are not there; and the sensation of crawling skin.

Hallucinations are different than delusions, vision changes, and dreams. Delusions are related to thought processes and conclusions. Vision changes, such as floaters, spots, and flashes of light, can be caused by conditions of your eye. Dreams occur while you are asleep.

Hallucinations are associated with some psychiatric disorders or medical conditions. Auditory hallucinations are most common. Psychiatric conditions associated with hallucinations include schizophrenia, schizoid and schizotypal personality disorders, psychotic depression, and bipolar disorder. Medical conditions affecting the central nervous system, such as brain tumors, delirium, dementia, epilepsy and other seizure disorders, and stroke, can be associated with hallucinations. Hallucinations can also be experienced with high fevers.

Some people abuse certain medications and substances because those items can cause hallucinations. Other substances, such as alcohol, can cause hallucinations when used in large quantities or during withdrawal. Hallucinations can be side effects of some medications and may occur with visual or hearing loss. Sleep deprivation or severe fatigue can also cause hallucinations.

Hallucinations can be symptoms of serious and even life-threatening conditions. Seek immediate medical care (call 911) if you, or someone you are with, experience hallucinations that cannot be distinguished from reality, or that are accompanied by bluish coloration of the lips or fingernails; chest pain or pressure; cold, clammy or dry, hot skin; confusion or loss of consciousness for even a moment; high fever (higher than 101 degrees Fahrenheit); persistent vomiting; rapid, slow or absent pulse; respiratory or breathing problems, such as rapid or slow breathing, shortness of breath, or no breathing; seizure; serious injury; severe abdominal pain; or threatening, irrational or suicidal behavior.

Seek prompt medical care if you are being treated for a condition that causes hallucinations and your symptoms are persistent, worsen, or otherwise cause you concern.

What other symptoms might occur with hallucinations?

Hallucinations may accompany other symptoms that vary depending on the underlying disease, disorder or condition. Symptoms that frequently affect the brain may also involve other body systems.

Psychological and cognitive symptoms that may occur along with hallucinations

Hallucinations may accompany other psychological or cognitive symptoms including:

  • Anxiety, irritability or agitation

  • Changes in mood, personality or behavior

  • Confusion, forgetfulness or disconnectedness

  • Delusions

  • Difficulty with memory, thinking, talking, comprehension, writing or reading

  • Heightened arousal or awareness

  • Mood depression or elevation

  • Mood instability

  • Poor judgment

  • Sleep disturbances

  • Withdrawal or depression

Other symptoms that may occur along with hallucinations

Hallucinations may accompany symptoms related to other body systems including:

Serious symptoms that might indicate a life-threatening condition

In some cases, hallucinations may be a symptom of a life-threatening condition that should be immediately evaluated in an emergency setting. Seek immediate medical care (call 911) if you, or someone you are with, have any of these life-threatening symptoms including:

  • Being a danger to oneself or others, including threatening, irrational or suicidal behavior

  • Bluish coloration of the lips or fingernails

  • Change in level of consciousness or alertness, such as passing out or unresponsiveness

  • Change in mental status or sudden behavior change, such as confusion, delirium, lethargy, hallucinations and delusions

  • Chest pain, chest tightness, chest pressure, palpitations

  • High fever (higher than 101 degrees Fahrenheit)

  • Rapid heart rate (tachycardia), slow heart rate (bradycardia), or abnormal heart rhythms (arrhythmias)

  • Respiratory or breathing problems, such as shortness of breath, difficulty breathing, labored breathing, slow breathing, not breathing, choking

  • Seizure

  • Severe and persistent vomiting

  • Severe pain

  • Trauma, such as bone deformity, burns, eye injuries, and other injuries

What causes hallucinations?

The specific cause of hallucinations is not known, but they can be associated with some psychiatric disorders or medical conditions. Substance abuse and withdrawal, medication side effects, sensory loss, sleep deprivation, and severe fatigue can all be associated with hallucinations.

Psychiatric causes of hallucinations

Hallucinations may be caused by psychiatric conditions including:

  • Bipolar disorder
  • Psychotic depression (depression with disordered thought processes)
  • Schizoid personality disorder (disorder characterized by detachment and isolation)
  • Schizophrenia
  • Schizotypal personality disorder (disorder characterized by a need for isolation, odd beliefs, and disordered thinking)

Other causes of hallucinations

Hallucinations can have other causes including:

  • Brain tumors
  • Delirium
  • Dementia
  • Medication side effects
  • Seizure disorders
  • Severe fatigue
  • Sleep deprivation
  • Substance abuse
  • Vision or hearing loss

Serious or life-threatening causes of hallucinations

In some cases, hallucinations may be a symptom of a serious or life-threatening condition that should be immediately evaluated in an emergency setting. These include:

  • Acute delirium (sudden onset of mental status changes due to illness or toxicity)
  • Seizures
  • Severe infections
  • Stroke

Questions for diagnosing the cause of hallucinations

To diagnose your condition, your doctor or licensed health care practitioner will ask you several questions related to your hallucinations including:

  • When did you first experience hallucinations?
  • What types of hallucinations are you having?
  • Can you describe your hallucinations?
  • Did any events or stresses precede your hallucinations?
  • Do you have any other symptoms?
  • Do you have any psychiatric or medical problems?
  • What medications are you taking?
  • Do you drink any alcohol?
  • Are you using any illicit drugs?

What are the potential complications of hallucinations?

Because hallucinations can be due to serious diseases, failure to seek treatment can result in serious complications and permanent damage. Once the underlying cause is diagnosed, it is important for you to follow the treatment plan that you and your health care professional design specifically for you to reduce the risk of potential complications including:

  • Brain damage
  • Coma
  • Difficulties at work, in school, in social environments, and with relationships
  • Drug and alcohol use and abuse
  • Drug overdose or alcohol poisoning
  • Increased risk of injury
  • Legal or financial troubles
  • Self-harm
  • Suicide or violence
Was this helpful?
Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Dec 14
THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
  1. Hallucinations. Medline Plus, a service of the National Library of Medicine National Institutes of Health. http://www.nlm.nih.gov/medlineplus/ency/article/003258.htm
  2. Hallucinations. Alzheimer’s Association. http://www.alz.org/living_with_alzheimers_hallucinations.asp
  3. Patkar AA, Mago R, Masand PS. Psychotic symptoms in patients with medical disorders. Curr Psychiatry Rep 2004; 6:216.