Agoraphobia is the fear of being alone in any place or situation from which it seems escape would be difficult or help unavailable should the need arise.

People with agoraphobia avoid being on busy streets or in crowded stores, theaters, or churches. Some people with agoraphobia become so disabled they literally will not leave their homes. If they do, they do so only with great distress or when accompanied by a friend or family member.

Two-thirds of those with agoraphobia are women. Symptoms develop between the ages of 18 and 35. The onset may be sudden or gradual.

Most people with agoraphobia develop the disorder after first suffering from one or more spontaneous panic attacks—feelings of intense, overwhelming terror accompanied by symptoms such as sweating, shortness of  breath, or faintness. These attacks seem to occur randomly and without warning, making it impossible for a person to predict what situation will trigger such a reaction.

The unpredictability of the panic attacks "trains" individuals to anticipate future panic attacks and, therefore, to fear any situation in which an attack may occur. As a result, they avoid going into any place or situation where previous panic attacks have occurred.