What Are Hallucinations

Hallucinations are an interesting psychological phenomenon where you see, hear, taste, smell or feel things that may appear natural but are not really there, occurring in your mind. Whilst they are usually associated with psychosis, they can occur for several different reasons. Some hallucinations may require treatment to resolve, some may resolve on their own and sometimes people live with the hallucinations. In this article we dive deeper into the subject of hallucinations, looking at the types of hallucinations, their causes and treatment.


Hallucinations have intrigued psychiatrists and other medical professionals for over 200 years. Whilst we know much about this psychological phenomenon, there is still more that requires exploring.1 Hallucinations are usually associated with mental health conditions such as schizophrenia or bipolar affective disorder but can occur as a result of many other reasons. These can usually be rectified by managing the underlying problem but sometimes requires longer-term support and management. Regardless of the cause, hallucinations can result in a great deal of distress and have resulted in people ending their lives by suicide. This emphasises the importance of taking hallucinations seriously and addressing the cause as soon as possible. 

Types of hallucinations

Visual: Seeing things that others do not. These tend to be deformed or altered versions of people, body parts, vivid images of faces, superimposed things, and things that can  not be identified.

Auditory: Auditory hallucinations can also take on many forms, with some people experiencing voices talking directly to them, or talking about them, these voices they hear are often rude or talk negatively about the person. Other auditory hallucinations may sound like a crowd of people talking or the person's thoughts being broadcasted aloud. Hearing voices as a third party, that is, as if someone else is talking, is a core diagnostic feature in schizophrenia.2

Olfactory: This is where you smell things that are not there, they can be either unpleasant or pleasant. Usually, this is caused by head injury, but can also be caused by an upper respiratory tract infection, ageing, trauma, frontal lobe seizures, brain tumours, or Parkinson’s disease.

Tactile: These involve false feelings or sensations of being touched by something, or something moving on your skin or inside you. These tend to be linked to mental health conditions, medications, or illicit drug use.

Gustatory: This type of hallucination alters your sense of taste, usually causing a strange or unpleasant taste such as a metallic taste. This type is a fairly common symptom for people with epilepsy.

Hypnagogic and hypnopompic hallucinations: This is a phenomenon whereby you experience hallucinations as you are falling asleep or during waking respectively. These are usually visual hallucinations, with an 86% prevalence.2  

Causes of hallucinations

Many things can cause hallucinations, from mental and physical health conditions to non-clinical circumstances such as drug intoxication or poor sleep. In this section, we explore a range of reasons someone might experience hallucinations.

Schizophrenia: It is said that 70% of all patients with schizophrenia experience some form of hallucination, with the most common being auditory hallucinations, followed by visual.

Affective disorders: Disorders associated with moods, such as bipolar affective disorder and major or severe depression, sometimes have hallucinations as part of their symptomatology. These tend to be auditory hallucinations, in the form of short phrases or single words.2 These auditory hallucinations are mood congruent, meaning they reflect the person's mood, for example, in major depression, they may hear derogatory voices, whereas in mania (elevated mood) the voices they hear may be affirming a delusional belief, such as a delusion of grandeur.

Postpartum/ postnatal psychosis: This is a phenomenon where a new mother may hear a baby crying when this is not the case. They may also hear derogatory voices telling them they are a bad mother, and in serious cases hearing a voice telling them to kill their baby.

Psychoactive substances: People who use illicit drugs often experience hallucinations as a direct result of consuming the psychoactive substances, however, prolonged use may increase your chances of developing long-term difficulties with psychosis.

Alcohol-related: People who drink alcohol regularly are at high risk of developing delirium tremens (severe withdrawal) if they suddenly stop drinking. This can result in hallucinations and seizures that can be life-threatening. People who drink alcohol excessively for a long time, run the risk of developing alcoholic hallucinosis, where the person experiences, predominantly auditory hallucinations during or immediately after heavy alcohol consumption.3

Post-traumatic stress disorder (PTSD): There are also strong links between childhood sexual abuse and hallucinations in PTSD.

Sleep disorder: About 80% of people will hallucinate if severely sleep-deprived. Hallucinations are one of the most common symptoms of severe sleep deprivation. People can also experience hypnagogic and hypnopompic hallucinations when falling asleep and upon waking respectively.

Delirium: Delirium is when a person's mental state worsens suddenly or over one or two days, usually with increased confusion and drowsiness. This could be due to infection, medication sensitivity, or constipation. Hallucinations occur in 40-75% of cases of delirium.2

Alzheimer’s disease: Most prevalent in the mid to later stages, hallucinations occur in 12-53% of cases.2 These tend to be visual hallucinations, but auditory, olfactory, and tactile can also occur.

Lewy body dementia: Hallucinations manifest as visual ones, predominantly, but one can experience auditory, olfactory, and tactile hallucinations. Prevalence is in the range of 46-65% of cases.

Parkinson’s disease: Some factors will increase the risk of hallucinations, such as age, reduced cognition, and sleep difficulties. Visual hallucinations are most frequent, but people may also experience auditory, olfactory, and tactile hallucinations. Some anti-Parkinson medications can also lead to an increase in hallucinations.

Sensory conditions: Some people who are deaf report hearing sounds, instruments, or singing. The theory for this is related to chronic sensory deprivation. Likewise, people blind from birth report visual hallucinations, this phenomenon is known as Charles-Bonnet syndrome and has a prevalence of 0.5-17%.2

Brain tumours: These can cause hallucinations and the type will depend on the area of the brain affected.

Epilepsy: Similar to brain tumours, epilepsy can cause hallucinations and the type will also depend on the area of the brain affected. 

Management and treatment for hallucinations

As hallucinations can stem from a variety of causes, the treatment will differ depending on their causation. Some hallucinations may be transient or temporary and associated with something that can be more easily rectified such as poor sleep or illicit drug use. Other causes of hallucinations may be more serious, requiring careful assessment and treatment with medication and psychological therapies.

Medication is often the most effective way of managing underlying complications such as delirium, pain, or alcohol withdrawal.

Sometimes, the hallucinations last a while and cause great distress, in which case, antipsychotic medication may be used to reduce the symptoms and alleviate the person's distress.

If someone is experiencing hallucinations as a result of a deterioration in their mental health and poses a danger to themselves or others, then a brief period in a psychiatric facility may be needed to reduce any risks.

If long-term management is needed, then certain psychological therapies can be used to help the person manage their symptoms.

Psychoeducation can be helpful in increasing the understanding of hallucinations. Helping others to understand the nature of hallucinations, removes the stigma of those who experience them.

Cognitive behavioural therapy(CBT) can be helpful in regulating emotional responses to the experience of hallucinations. The limitation of CBT is that it works on the response to the hallucinations rather than addressing the hallucinations themselves.2

Hallucination-focused integrative treatment or HIT consists of different strategies to maximise control of persistent auditory hallucinations. It integrates CBT, psychoeducation, coping skills, and medication. This intervention includes  20 sessions over 9–12 months. Studies suggest that HIT is effective for people with chronic schizophrenia with auditory hallucinations. 


Initially a doctor will try to find the cause of the hallucinations by taking a medical history and conducting an assessment. You will be asked about your symptoms, such as when they started, when they are worst, and what type of hallucinations you are experiencing.

It is sometimes the case that finding the cause takes some time. In these cases, the hallucinations may be treated with medication. A doctor will usually check for the most obvious causes first, for example, a frail older adult will be checked for dehydration, urinary tract infection, sensory difficulties, pain, or constipation. Further investigations may be needed if no cause can be initially found. Brain scans can be used to rule out stroke or epilepsy as a cause.

A person may have a preexisting mental health condition with hallucinations as a symptom, in which case, medication compliance is checked and a review from a psychiatrist will be needed.

It is usually the case that if you find the underlying cause, such as alcohol withdrawal or delirium, then once that has been addressed, the hallucinations cease.  


How can I prevent hallucinations

Although there is no definitive way to prevent hallucinations, there are things you can do to reduce your risk of developing hallucinations. In order to optimise your resilience to developing hallucinations ensure you:

  • Reduce and manage stress
  • Maintain good sleep hygiene and sleep sufficiently
  • Avoid regular excessive alcohol use
  • Avoid using illicit drugs/ psychoactive substances
  • Keep yourself well hydrated and well nourished
  • Be mindful of the side effects when starting new medication

How common are hallucinations

A study in 2021 for the British Journal of Psychiatry explored the prevalence of hallucinations in the general population. The study found that prevalence varied across the age groups. The highest prevalence was 7% in the 16-19 age group, and this decreased to 3% in the over-70s age group.4

What’s the difference between hallucinations and delusions

Both hallucinations and delusions are symptoms of psychosis and there is some overlap between the two, primarily that they are both an altered reality. The key difference is that hallucinations are sensory, whilst delusions are cognitive.5

Who are at risk of hallucinations

Hallucinations affect people of all ages from children to older adults. But some groups of people are more susceptible than others.

  • Children and adolescents: This has been identified as a high-risk group, reflected in the high prevalence.6 The reason for this is said to be related to childhood difficulties and trauma, coupled with undeveloped coping strategies. A study in 2022 also highlights, however, that assessment of hallucinations in children is not reliable enough at present, which means the actual prevalence may not be accurate.6
  • Psychoactive substance users.
  • Older adults: Specifically, those over the age of 70. This age group has greater sensitivity to certain medications, which can cause delirium, in which hallucinations are common. Older adults are more likely to be dehydrated and/ or have urinary tract infections which can cause hallucinations. Also, delirium is common following major surgery such as hip replacement or following neck of the femur fractures following falls. Older adults are also more likely to develop Lewy-body dementia, Parkinson’s disease, and Alzheimer’s which also have hallucinations as part of their symptomatology.
  • People with alcohol use disorder.
  • Anyone who has experienced trauma: Those who experience significant trauma resulting in post-traumatic stress disorder (PTSD).
  • Those who have a family history of hallucinations or mental illness where psychosis is a symptom.
  • New mothers can experience hallucinations due to postpartum psychosis.
  • People with sleep disorders. 

When should I see a doctor

If you are experiencing any of the listed symptoms, you should contact your doctor Immediately. You may or may not realise that you are experiencing hallucinations and it might be someone close to you that recognises that you are experiencing hallucinations. Whatever the cause of these hallucinations, if you or someone else notice them you will likely need assessment and treatment to resolve this. Hallucinations could be a sign of a serious mental health problem such as schizophrenia or it could be a sign of a serious, even life-threatening underlying physical health complaint such as delirium or acute alcohol withdrawal. 


Hallucinations are a phenomenon of great interest, especially in psychiatry. Whilst usually associated with schizophrenia and psychosis, they can occur as part of other conditions. Sometimes transient, they may come and go quickly with little to no concern. Usually, however, they are a result of a more serious condition that causes great distress to the person and/ or those close to them. These hallucinations of a more serious nature require careful assessment and immediate intervention to prevent a worsening of symptoms and more serious consequences. 

For the more serious hallucinations, those associated with schizophrenia or psychosis, pharmacological intervention with antipsychotics may be necessary. For most other causes of hallucinations, once the cause has been identified and treated, the hallucinations recede and disappear.

If you or someone you know is believed to be experiencing hallucinations, seek medical help immediately to explore the cause and seek treatment if it is needed. 


  1. Kumar S, Soren S, Chaudhury S. Hallucinations: Etiology and clinical implications. Ind Psychiatry J [Internet]. 2009 [cited 2023 Jun 30];18(2):119–26. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2996210
  1. Chaudhury S. Hallucinations: Clinical aspects and management. Ind Psychiatry J [Internet]. 2010 [cited 2023 Jun 30];19(1):5–12. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3105559/
  1. Bhat PS, Ryali V, Srivastava K, Kumar SR, Prakash J, Singal A. Alcoholic hallucinosis. Ind Psychiatry J [Internet]. 2012 [cited 2023 Jun 30];21(2):155–7. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3830167/
  1. Yates K, Lång U, Peters EM, Wigman JTW, McNicholas F, Cannon M, et al. Hallucinations in the general population across the adult lifespan: prevalence and psychopathologic significance. The British Journal of Psychiatry [Internet]. 2021 Dec [cited 2023 Jun 30];219(6):652–8. Available from: https://www.cambridge.org/core/journals/the-british-journal-of-psychiatry/article/hallucinations-in-the-general-population-across-the-adult-lifespan-prevalence-and-psychopathologic-significance/16DCD1BEEC45873A3CA16BAC22C442B5
  1. Rodríguez-Testal JF, Senín-Calderón C, Moreno R. Hallucinations and delusions as low-quality attributions: influencing factors and proposal for their analysis. Front Psychol [Internet]. 2021 Jul 23 [cited 2023 Jun 30];12:533795. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8342811/
  2. Michelangelo Di Luzio, Maria Pontillo, Cristina Di Vincenzo, Domenica Bellantoni, Francesco Demaria, Stefano Vicari. Hallucinations in the Child and Adolescent “Ultra-High Risk” population: A Systematic Review. Schizophrenia Bulletin Open [Internet]. 2022 Nov 04 [cited 2023 Jun 30]. Available from: https://academic.oup.com/schizbullopen/article/3/1/sgac068/6798852
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Karl Jones

BA Hons in Learning Disability Nursing, Diploma in Mental Health Nursing (Oxford Brookes

Karl has 12 years of experience in learning disability and mental health nursing in a variety of
settings. He has worked predominantly in general hospitals specialising in suicide prevention and the
psychological impact on long term health conditions. Most recently he has worked as a clinical
educator in the field of mental health. He is currently focusing on writing as a career with the aim of
imparting his knowledge to a wider audience.

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