• A marked, persistent, excessive, and unreasonable fear of an object, activity, place, or situation
    • Symptoms develop in the presence/anticipation of the triggering factor(s). These factors are actively avoided/endured with extreme anxiety and dread.
    • The fear, anxiety, or avoidance typically lasts for 6 months or more.
  • To qualify as a disorder, symptoms must cause significant distress, interfere with normal social and vocational functioning, and result in a perceived loss of freedom.
  • The American Psychiatric Association classifies phobias as anxiety disorders and divides them into three following categories:
    • Agoraphobia: excessive/irrational fear and avoidance of situations that may be difficult to escape. May involve fear of crowds, enclosed spaces (e.g., elevators, automobiles, or airplanes), or simply being alone (at home or away from home). Usually secondary to a coexisting panic disorder but may be a primary condition. See the topic “Panic Disorder.”
    • Specific phobia (formerly simple phobia)
      • Excessive/irrational fear and avoidance of clearly discernible, circumscribed objects/situations; often divided into animal type (e.g., snakes, spiders), environmental type (e.g., storms, height), blood-injection/injury type, or situational type (e.g., enclosed spaces, flying, crowds)
      • Common specific phobias: zoophobia (animals), brontophobia (thunderstorms), acrophobia (heights), nosophobia (disease), thanatophobia (death)
      • Blood-injection/injury phobia associated with a strong vasovagal reaction
    • Social phobia (social anxiety disorder): excessive/irrational fear and avoidance of certain social/performance situations where embarrassment/humiliation may occur under scrutiny of others. Individuals may experience marked anticipatory anxiety in advance of upcoming feared events; one of the most common (and underdiagnosed) phobias

Pediatric Considerations

  • Anxiety may be expressed by crying, tantrums, or clinging. Fear of animals and other environmental objects are usually transitory in childhood.
  • Preadolescent children are often not aware that their fears are excessive or unreasonable.



  • Predominant age: mean age of onset 20 years for agoraphobia, 15 years for specific phobias, 15 years for social phobia
  • Predominant sex: female > male

In the general U.S. population, the 12-month and lifetime prevalence, respectively are as follows:

  • Agoraphobia without panic: 0.8% and 1.4%
  • Specific phobia: 8.7% and 12.5%
  • Social phobia: 6.8% and 12.1%

Etiology and Pathophysiology

  • Not well understood, but exaggerated amygdala, anterior cingulate, and insular activity increase fear and create mental stress–induced heart rate, and BP increases
  • A complex interplay of genetic vulnerability, developmental neurobiology, and environmental vulnerability may lead to persistence/exaggeration of a learned response, perhaps learned initially as a protective mechanism (e.g., avoidance of large dogs by a child).


  • Social phobia and agoraphobia are correlated with genetically influenced introversion and neuroticism.
  • Specific phobias tend to run in the family, especially blood-injection/injury type, which has very high familial tendency.

Risk Factors

  • Female sex (Phobias are the most common psychiatric disorders among women.)
  • First-degree relatives with the disorder
  • Traumatic experience
  • In children, observation of others with phobic reactions
  • Social phobia is strongly associated with a perceived lack of control over one’s own life. Other risk factors include low self-esteem, low education level, emotional neglect, major depression, and significant recent life stressors.

Commonly Associated Conditions

  • Other anxiety and mood disorders as well as abuse of alcohol and other substances
  • Most patients with agoraphobia experience panic disorder as well.

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