Hallucinations are false perceptions of sensory experiences. Some hallucinations are normal, such as those caused by falling asleep or waking up. But others may be a sign of a more serious condition like schizophrenia or dementia.
A hallucination is a false perception of objects or events involving your senses: sight, sound, smell, touch and taste. Hallucinations seem real, but they’re not. Chemical reactions and/or abnormalities in your brain cause hallucinations.
Hallucinations are typically a symptom of a psychosis-related disorder, particularly schizophrenia, but they can also result from substance use, neurological conditions and some temporary situations.
A person may experience a hallucination with or without the insight that what they’re experiencing isn’t real. When a person thinks their hallucination is real, it’s considered a psychotic symptom.
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There are several different types of hallucinations, including:
There are also types of hallucinations that are sleep-related, including:
A hallucination is a sensory experience. It involves seeing, hearing, tasting, smelling or feeling something that isn't there.
Delusions are unshakable beliefs in something untrue. For example, they can involve someone thinking they have special powers or they’re being poisoned despite strong evidence that these beliefs aren’t true.
Hallucinations are a perception not based on sensory input, whereas illusions are misinterpretations of sensory inputs. In other words, hallucinations involve experiencing something that doesn’t exist.
Illusions happen when you misinterpret something real in your environment.
For example, you might mistake a black bag sitting on a window sill for a black cat. Upon further examination, you realize that it’s a bag and not a cat. This is an illusion.
It’s possible to experience hallucinations while being aware that they aren't real.
For example, some people grieving the death of a loved one may momentarily hear their deceased loved one’s voice or see them, but they know that what they’re hearing or seeing is impossible. Most people are also able to tell that the hallucinations that happen when they’re falling asleep or waking up aren’t real.
In these cases, you can use context clues and your environment to tell that what you’re “experiencing” isn’t real.
However, some people don’t realize that they’re hallucinating. This is more common in chronic conditions like schizophrenia and dementia.
There are many possible causes of hallucinations, including:
The following conditions or situations may temporarily cause hallucinations:
Experiencing hallucinations in these ways is usually not a cause for concern. However, if you have an acute medical issue that’s causing them, like an infection or a fever, it’s important to seek medical treatment for the issue.
Schizophrenia is the main mental health condition that causes hallucinations. Schizophrenia refers to both a single condition and a spectrum of conditions that fall under the category of psychosis-related disorders. These are conditions where a person experiences some form of “disconnection” from reality (psychosis), which can include hallucinations.
Conditions that fall under the schizophrenia spectrum and may cause hallucinations include:
Hearing voices is the most common type of hallucination in people with these mental health conditions.
Other mental health conditions that may cause hallucinations include:
Neurological conditions that may cause hallucinations include:
Charles Bonnet syndrome causes a person whose vision has started to deteriorate to see hallucinations. This condition only causes visual hallucinations.
Many prescription medications can occasionally cause or worsen hallucinations as a side effect. Elderly people may be at greater risk due to increased sensitivity to medications. Hallucinations caused by medications may be dose-related and usually stop when you discontinue the medication. Your healthcare provider is the best source of information about medication side effects. Never stop taking a medication without speaking to your healthcare provider first.
The treatment for hallucinations depends on the cause. Hallucinations caused by temporary conditions, such as high fever, severe dehydration or infection, will resolve once the underlying condition has been treated.
Certain medications and therapies may help treat hallucinations in people with chronic conditions that cause them, including:
While not all hallucinations can be prevented, there are some strategies you can use at home that might help reduce the frequency of them for certain people with neurological conditions that may cause hallucinations, including:
If you’re taking medication to help treat hallucinations, it’s important to continue taking the medication unless your healthcare provider tells you otherwise. Stopping the medication suddenly can cause more intense hallucinations.
If you’re with someone who’s experiencing a hallucination, there are some steps you should take:
If you or someone you know is experiencing hallucinations and is detached from reality, you or they should get checked by a healthcare provider as soon as possible.
Many medical and mental health conditions that can cause hallucinations may quickly become emergencies. The person experiencing hallucinations shouldn’t be left alone.
A note from Cleveland Clinic
It’s important for people experiencing hallucinations to talk about them with their family and healthcare team. Hallucinations are manageable with treatment and can become disturbing or dangerous if they’re not treated. Discuss all possible symptoms with your healthcare provider, no matter how minor or bizarre you may think they are. Hallucinations can make you feel nervous, paranoid and frightened, so it's important to be with and talk with someone you can trust.
Last reviewed by a Cleveland Clinic medical professional on 06/26/2022.
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