Difference Between Hallucinations and Delusions (With Table)

There are some diseases and disorders that can be very harmful if not notice, and proper precautions are not taken at the right time. Disorders are the situation where a person cannot function like a normal person; he finds it difficult to perform simple tasks. Example of such disorders is hallucinations and delusions. Both of them are disorders where a person seems to see things that are not actually there in reality. Both of them involve perception. Due to their similarities, it becomes difficult to differentiate between both of the disorders. To treat them and take precautions, it is important to have all the important information about them.

Hallucinations vs Delusions

The difference between Hallucinations and Delusions is that both of them include different types of perceptions. In hallucination, a person’s sense responds differently to things that are not real or present. He hears, feels, sees, or touches the things that are not even there in reality, whereas in delusions, the person tends to believe in things that are not possible or on false perception. For example, when a person can hear sounds of other people when in reality he is alone, it is hallucinations, and when a person beliefs he is immortal and can never die, it is delusions.

Hallucination is a disorder of senses; it includes seeing, feeling, hearing, or even touching something by the patient that is not present there. The causes behind these are categorized as primary and secondary. There are many types of hallucinations based on the senses mainly.

Delusions are a disorder of false belief; it includes believing in false facts. In this, a person can believe something that is impossible. The causes behind this are mainly related to mental disorders. A person can be treated with this order by therapy and medications.

Comparison Table Between Hallucinations and Delusions

Parameters of ComparisonHallucinationsDelusions
What is it?Sensory perceptionFalse belief
SymptomsRespond to things that are not present.Belief in things that are based on false perception.
TreatmentSymptomatically with anti-psychoticsPsychotherapy and drugs
Caused byIt can be caused by many things, sleep deprivation, alcohol withdrawalPsychological or neurological disorders

What are Hallucinations?

Hallucination does not only include seeing things; it also includes hearing and touching the things that are not present at the moment. And on the basis of this, there are types of hallucinations:

  1. Auditory Hallucination: this means hearing hallucinations. In this, the person hearing something that is not there. For example, hearing people talk when no one is there beside you. The cause of this hallucination can be Schizophrenia, Bipolar disorder, Borderline personality disorder, Posttraumatic stress disorder, Sleep disorders, Brain lesions, Psychosis, Hearing loss, Drug use, etc.
  2. Visual Hallucination: it means seeing a hallucination where a person sees something that is not there in reality. For example, seeing an insect somewhere when there is nothing. Possible causes for this can be, Irritation in the visual cortex, the part of your brain that helps you see, Schizophrenia, Schizoaffective disorder, Delirium (from infections, drug use, and withdrawal, or body and brain problems), Dementia, Damage to brain tissue (the doctor will call this lesions), Sleep problems, Creutzfeldt-Jakob disease, Drugs that make you hallucinate, Metabolism problems, Depression, Seizures, Migraines, Bipolar disorder, Parkinson’s disease, brain lesions, and tumors, etc.
  3. Olfactory and Gustatory Hallucination: these mean smelling and tasting hallucinations, respectively. It means the person smells an unusual odor coming from somewhere or tasting a different taste. The cause of these can be head injury, cold, brain tumors, Parkison disease, alcohol, drugs, etc.
  4. Tactile or Somatic Hallucinations: this means feeling things hallucination. For example, you might feel ticklish or that someone is touching you when there is no one. The cause of this can be alcohol, drugs, Schizophrenia, Schizoaffective disorder, Alzheimer’s disease, Lewy body dementia, Parkinson’s disease, etc.

What are Delusions?

It is a state of disorder where a person beliefs in things that are not true, and a person are considered to be in a delusion state if the following criteria are fulfilled:

  1. Certainty: the perception starting believing in something or someone that does not exist.
  2. Incorrigibility: it is means when the false belief by the person cannot be changed.
  3. Impossibility: it means there is no chance of the belief being true. It is completely false.

The exact reason behind the development of the delusions is not clear, but there might be something that can cause them such as, some genetic factor or physiological disorder pre-existed. People experience several types of delusions, which are mainly categorized as primary and secondary. Primary delusions are those behind them, there is no preceding reason, and it suggests the state of schizophrenia, and secondary is the one behind which there can be a reason (mental disorder) such as depression. Another category of delusions is monothematic and polythematic. In monothematic, delusion is built up of one story, whereas in polythematic, it is built up of big and multiple stories.

Main Differences Between Hallucinations and Delusions

  1. The main difference between Hallucinations and Delusions is that Hallucination is based on the sensory perception of a human being, whereas Delusions are based on the false belief of a person.
  2. In terms of center, hallucination is centered on sense, where a person’s senses do not respond to the things that are there, or they respond to something that is not present in reality, whereas delusions centered on beliefs of a person, where he beliefs scenarios that are not true or real.
  3. Both of them include different symptoms. The most common symptom of hallucinations is responding to things by talking, feeling, seeing, etc., that are even real or there at the moment, whereas the common symptoms of delusions include believing in things based on a false or incorrect perception.
  4. In terms of treatment also both of the disorders differ. In the case of hallucination, treatment symptomatically along with the anti-psychotics are used while for treating delusions, mostly psychotherapy is used along with the drugs or medications.
  5. Lastly, they also differ in terms of their causes, the main cause of delusions are mostly psychological or neurological disorders, whereas there are many causes of hallucinations based on the type, but the most common are genetic factors, alcohol withdrawal, etc.


There should not be any confusion between both hallucinations and delusions. In these disorders, people find it difficult to separate realities from dreams or sees things/people not actively present over there. Both of them can be caused by similar accidents such as from certain mental illnesses or can be caused by some triggers, etc. it is important to know the difference as till then you can’t treat them. Both of them can cause a person to behave differently and irrationally. He might get frustrate or irritate easily due to this disorder. Treatment of this disorder might take time as most of the time, people do not accept they are suffering from this disorder, and after acceptance, it takes time to treat properly.


  1. https://jamanetwork.com/journals/jamapsychiatry/article-abstract/490108
  2. https://jnnp.bmj.com/content/70/6/734.short
  3. https://n.neurology.org/content/54/10/1965.short
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