What causes paranoia?

The exact cause of paranoia is not known. It may be related to a chemical imbalance in the brain, heredity, stress, or a traumatic life event. In some cases it may be due to injury or infection of the brain. Usually, paranoia is a symptom of a mental illness.

Mental disorder causes of paranoia

Paranoia may be caused by a variety of mental disorders including:

  • Agoraphobia
  • Obsessive compulsive disorder
  • Paranoid personality disorder
  • Schizophrenia

Other causes of paranoia

Paranoia can also be caused by a variety of events or other conditions including:

  • Drug abuse
  • Head injury or infection
  • Heredity
  • Social repression
  • Stress
  • Traumatic life event

Questions for diagnosing the cause of paranoia

To diagnose your condition, your doctor or licensed health care practitioner will ask you several questions related to your paranoia including:

  • How long have you felt your paranoia? Or, when did you first notice your paranoia?
  • Are there specific events that trigger your paranoia?
  • Do you have a family history of mental illness?
  • Do you have any other symptoms?
  • Have you had a recent injury or infection?
  • Have you had a recent lifestyle change or difficult life event?
  • What medications are you taking?

What are the potential complications of paranoia?

Paranoia is often difficult to treat due to the suspicion of health care workers. Because people with paranoia do not seek treatment, it is likely that any problem underlying the paranoia will be allowed to continue. Because paranoia can be due to serious diseases, failure to seek treatment can result in serious complications and permanent damage. Once the underlying cause is diagnosed, it is important for you to follow the treatment plan that you and your health care professional design specifically for you to reduce the risk of potential complications including:

  • Absenteeism from work or school
  • Adverse effects of treatment
  • Development of an anxiety disorder
  • Development of another mental disorder
  • Inability to perform daily tasks
  • Loss of employment
  • Loss of relationships
  • Social isolation


  1. Schizophrenia. National Institute of Mental Health. http://www.nimh.nih.gov/health/publications/schizophrenia/complete-index.shtml.
  2. Paranoid personality disorder. PubMed Health, a service of the NLM from the NIH. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001934/
  3. Domino FJ (Ed.) Five Minute Clinical Consult. Philadelphia: Lippincott Williams & Wilkins, 2013.
  4. Kuepper R, van Os J, Lieb R, et al. Continued cannabis use and risk of incidence and persistence of psychotic symptoms: 10 year follow-up cohort study. BMJ 2011; 342:d738.

What is paranoia?

Paranoia refers to feelings of distrust, suspicion, or persecution that are not based in reality. Paranoia is a kind of delusion in which a person thinks he or she is being singled out in a negative way. People with paranoia will look for evidence to prove they are being singled out, and refuse to see that they have an exaggerated view of their own significance.

The exact cause o... Read more about paranoiaintroduction


What other symptoms might occur with paranoia?

Paranoia may accompany other symptoms, which vary depending on the underlying disease, disorder or condition. Mental and emotional symptoms such as paranoia may be a sign of a complicated mental illness.

Schizophrenia symptoms that may occur along with paranoia

Paranoia may accompany other symptoms related to schizophrenia including:

Medical Reviewer: William C. Lloyd III, MD, FACS Last Annual Review Date: Sep 20, 2013 Copyright: © Copyright 2014 Health Grades, Inc. All rights reserved. May not be reproduced or reprinted without permission from Health Grades, Inc. Use of this information is governed by the HealthGrades User Agreement.

This Article is Filed Under: Mental Health and Behavior