A persistent excessive fear of an object or situation that is not of real danger. Examples include claustrophobia (fear of confined spaces), agoraphobia (fear of being in the open), specific phobias (as for spiders, mice, thunder, or darkness), and social phobias (such as excessive anxiety in the presence of other people).

Phobias, especially specific phobias, may be isolated abnormalities in an otherwise normal person, or they may sometimes be a manifestation of underlying anxiety or depression of a more general nature. It is theorized that phobias may represent a prolonged response to an unpleasant experience in childhood; the original stimulus usually has been forgotten.

Phobias produce three main kinds of response: (1) a subjective experience of fear for the object or situation; (2) physiological changes such as palpitations or blushing in response to it; and (3) behavioral tendencies to avoid or escape from it. Some truly phobic persons rarely experience symptoms because they avoid the feared situation, and persons with a severe phobia may have difficulty seeking treatment.

Persons with underlying anxiety or depressive states often benefit from drug therapy or psychotherapy, but most other phobias are resistant to these techniques. Here the most effective therapy is often "desensitization," a form of behavior therapy in which the person is taught gradually to relax while imaging the feared object. An alternate technique is "flooding" or "implosion" therapy, in which the person is confronted by the feared object or situation and encouraged to remain in contact with it until his anxiety disappears.

Therapy for phobias is not always successful, and "cures" are not always permanent, but most sufferers can be helped by current treatments. The understanding and patience of family and friends are essential.