Difference Between Delusion and Hallucination

Main Difference – Delusion vs Hallucination

Hallucinations and delusions are two psychotic symptoms which are highly prevalent in the modern society, especially among people with a positive family history and other associated mental illnesses. But, it doesn’t necessarily mean that individuals who go through these episodes are suffering from underlying mental conditions. For example, alcoholics and drug abusers may experience hallucinations and delusions without having any health condition. However, it is highly encouraged to identify and treat these affected individuals since possible undiagnosed or underlying health issues should be treated before turning into worse pathologies. The main difference between delusion and hallucination is that delusion is a fixed yet false belief which is often fanciful and derived by deception whereas hallucination is a faulty perception in the absence of any external stimulus.

This article describes,

1. What is Delusion – Definition, Meaning, Causes, Symptoms, Treatment Methods

2. What is Hallucination – Definition, Meaning, Causes, Symptoms, Treatment Methods

3. Difference Between Delusion and Hallucination

Difference Between Delusion and Hallucination - Delusion vs. Hallucination Comparison Summary

What is Delusion

The term ‘Delusion’ is defined as a false belief that is strongly based on a faulty perception of reality. More importantly, the particular belief is withheld despite any proper and contrary evidence and is not influenced by the individual’s culture or religion.

According to the psychiatrist Karl Jaspers, for a scenario to be accepted as a delusion, it should fulfill three main criteria known as Certainty, Incorrigibility, and Impossibility

Certainty: the patient believes in faulty perception or the delusion

Incorrigibility: the belief cannot be changed by any means

Impossibility: the delusion is absolutely false without any doubt

Even though the exact etiology for the development of delusions is not clear, poor self-esteem and a positive family history are thought to be important factors. Psychotic disorders and neurological disorders like Dementia are also known to predispose delusions in many cases.

People may experience various types of delusions which can either be primary or secondary and monothematic or polythematic. Primary delusions are fully formed and has no preceding reasons which usually suggest schizophrenia where secondary delusions are found among people with underlying mental disorders like depression. Furthermore, Monothematic delusions are built up around a single topic whereas polythematic delusions involve multiple topics usually developing a whole big confusing story.

Delusions are usually treated with a combination of psychotherapy and drug therapy including anti-depressants, antipsychotics, and anxiolytics.

Main Difference - Delusion vs Hallucination

Psychotic disorders and neurological disorders like Dementia are also known to predispose delusions in many cases.

What is Hallucination

A hallucination is defined as a sensory perception, experienced in the absence of any external stimulus which usually occurs with the involvement of various senses including visual, auditory, olfactory or tactile.

Being the commonest type of hallucination experienced, auditory hallucinations are common among adolescents who have a positive family history of psychosis whereas most of the people who see visual hallucinations are known to be suffering from underlying mental conditions like Schizophrenia and Schizoaffective disorder. According to latest research studies, about 75% of individuals affected with hallucinatory symptoms have found to be otherwise completely healthy.

Other commonest etiological factors for hallucinations include Parkinson’s disease, Lewy body dementia, Delirium tremens, sleep deprivation, ophthalmological conditions like cataract, migraine, childhood trauma and chronic drug abuse.

Furthermore, a hallucination to be defined as such, it must take place in the context of a clear cut sensorium where instances which occur during sleep (hypnagogic) or getting up from sleep (hypnopompic) are known to be completely normal experiences.

Hallucinations are treated symptomatically with anti-psychotic drugs where a suspected underlying mental condition should be treated accordingly.

Difference Between Delusion and Hallucination

Difference Between Delusion and Hallucination


Delusion: A delusion is defined as a fixed yet false belief which is often fanciful and derived by deception.

Hallucination: A hallucination is defined as a faulty perception in the absence of any external stimulus.


Delusion: A person who is getting delusions generally has a strong belief which may or may not be based on any true perception. Also, delusions can often appear irrational or bizarre to people around.

Hallucination: A person who is experiencing hallucinations may hear voices talking to him, so he will tend to respond to those faulty voices which will often appear as real conversations to others around him.


Delusion: Delusions mostly occur due to underlying psychological or neurological disorders.

Hallucination:Hallucinations can occur as a result of sleep deprivation, alcohol withdrawal or drug abuse as well  as secondary to psychological conditions like schizophrenia.


Delusion:Delusions often need psychotherapy in combination with drugs like antipsychotics, antidepressants, and anxiolytics.

Hallucination:Hallucinations can be treated symptomatically with anti-psychotics alone.

Image Courtesy: 

“Delirium” by   via

“A woman diagnosed as suffering from chronic dementia. Colour Wellcome L0026688″ By via

About the Author: Embogama

Embogama is a passionate freelance writer for several years. Her areas of interest include general medicine, clinical medicine, health and fitness, Ayurveda medicine, psychology, counseling and piano music

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