Definition

Psychosis occurs when a person loses contact with reality. The person may:

• Have false beliefs about what is taking place, or who one is (delusions)
• See or hear things that are not there (hallucinations)

Causes

Medical problems that can cause psychosis include:

• Alcohol and certain illegal drugs, both during use and during withdrawal
• Brain diseases, such as Parkinson disease and Huntington disease
• Brain tumors or cysts
• Dementia (including Alzheimer disease)
• HIV and other infections that affect the brain
• Some prescription medicines, such as steroids and stimulants
• Some types of epilepsy
• Stroke

Psychosis may also be found in:

• Most people with schizophrenia
• Some people with bipolar disorder (manic-depressive) or severe depression
• Some personality disorders

Symptoms

A person with psychosis may have any of the following:

• Disorganized thought and speech
• False beliefs that are not based on reality (delusions), especially unfounded fear or suspicion
• Hearing, seeing, or feeling things that are not there (hallucinations)
• Thoughts that jump between unrelated topics (disordered thinking)

Exams and Tests

Psychiatric evaluation and testing are used to diagnose the cause of the psychosis.

Laboratory testing and brain scans may not be needed, but sometimes can help pinpoint the diagnosis. Tests may include:

• Blood tests for abnormal electrolyte and hormone levels
• Blood tests for syphilis and other infections
• Drug screens
• MRI of the brain

Treatment

Treatment depends on the cause of the psychosis. Care in a hospital is often needed to ensure the person's safety.

Antipsychotic medicines, which reduce hallucinations and delusions and improve thinking and behavior, are helpful.

Outlook (Prognosis)

How well a person does depends on the cause of the psychosis. If the cause can be corrected, the outlook is often good. In this case, treatment with antipsychotic medicine may be brief.

Some chronic conditions, such as schizophrenia, may need lifelong treatment with antipsychotic medicines to control symptoms.

Possible Complications

Psychosis can prevent people from functioning normally and caring for themselves. Left untreated, people can sometimes harm themselves or others.

When to Contact a Medical Professional

Contact your health care provider or mental health professional if you or a member of your family is losing contact with reality. If there is any concern about safety, take the person to the emergency room to be seen by a provider.

Prevention

Prevention depends on the cause. For example, avoiding alcohol prevents psychosis caused by alcohol use.

References

American Psychiatric Association. Schizophrenia spectrum and other psychotic disorders. Diagnostic and Statistical Manual of Mental Disorders. 5th ed. Text Revision (DSM-5-TR), Washington, DC: American Psychiatric Association Publishing; 2022.

Lim C, Paudel S, Holt DJ, Freudenreich O. Psychosis and schizophrenia. In: Stern TA, Wilens TE, Fava M, eds. Massachusetts General Hospital Comprehensive Clinical Psychiatry. 3rd ed. Philadelphia, PA: Elsevier; 2025:chap 27.

Lyness JM, Lee HB. Psychiatric disorders in medical practice. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 362.