The anxiety caused by a phobic disorder can interfere with daily living because people avoid certain activities and situations.
The diagnosis is usually obvious based on symptoms.
Treatment usually consists of exposure therapy.
Specific phobias are common anxiety disorders Overview of Anxiety Disorders Anxiety is a feeling of nervousness, worry, or unease that is a normal human experience. It is also present in a wide range of psychiatric disorders, including generalized anxiety disorder,... read more that affect about 8% of adults in a given 12-month period. The most common specific phobias include fear of animals (zoophobia), fear of heights (acrophobia), and fear of thunderstorms (astraphobia or brontophobia). At least 5% of people are at least to some degree afraid of blood, injections, or injury. People who have a specific phobia often have two or more phobias. People who have a specific phobia avoid specific situations or objects that trigger their anxiety and fear, or they endure them with great distress, sometimes resulting in a panic attack Panic Attacks and Panic Disorder A panic attack is a brief period of extreme distress, anxiety, or fear that begins suddenly and is accompanied by physical and/or emotional symptoms. Panic disorder involves recurrent panic... read more . However, they recognize that their anxiety is excessive and therefore are aware that they have a problem.
Some specific phobias cause little inconvenience. For example, a city dweller who is afraid of snakes may have no trouble avoiding them. Other specific phobias greatly interfere with functioning. For example, a city dweller who fears elevators may encounter them frequently and thus be routinely faced with a difficult choice: avoid an important work situation, climb many stairs, or endure the elevator ride with great discomfort.

Diagnosis of Specific Phobic Disorders
A doctor's evaluation, based on specific criteria
Doctors diagnose a specific phobic disorder when people have fear of or anxiety that involves all of the following:
Is intense and has been present 6 months or longer
Concerns a specific situation or object
Occurs immediately when the situation or object is encountered
Leads to avoidance of the situation or object
Is out of proportion to the actual danger
Causes significant distress or significantly impairs functioning
Also, doctors rule out other mental disorders that can cause similar symptoms, such as agoraphobia Agoraphobia Agoraphobia is fear or anxiety about being in situations or places with no way to escape easily or in which help might not be available if intense anxiety develops. These situations or places... read more , social anxiety Social Phobia Social phobia is fear or anxiety about certain social or performance situations. These situations are often avoided or endured with much distress. Humans are social animals, and their ability... read more , or a stress disorder. Overview of Trauma- and Stress-Related Disorders Trauma- and stress-related disorders result from exposure to a traumatic or stressful event. Specific disorders include acute stress disorder and posttraumatic stress disorder. These disorders... read more
Treatment of Specific Phobic Disorders
Exposure therapy
Some people do well without treatment because the situation or object they fear is easy to avoid. Bats and caves are examples. If situations or objects (such as thunderstorms) are commonly encountered, treatment is often needed.
Exposure therapy, a type of psychotherapy, is the treatment of choice. Exposure therapy involves exposing people gradually and repeatedly—in their imagination or sometimes in reality—to whatever triggers their fear. People are also taught relaxation and/or breathing techniques to use before and during exposure. Exposure therapy is repeated until people become very comfortable with the anxiety-provoking situation. A therapist can help ensure that the therapy is carried out correctly, although people can do it on their own.
Exposure therapy helps more than 90% of people who do it faithfully. It is almost always the only treatment needed for specific phobias. Even people with a phobia of blood or needles respond well to exposure therapy. For example, such people might begin the exposure by just visiting a doctor's office (or perhaps just walking by the office). The next day (or week), they might sit in an exam room with no intention of getting any blood drawn. The next step might be allowing a needle to be brought close to their skin. Exposure may increase quickly or slowly, but eventually people should allow blood to be drawn.
Drug therapy is not very useful in helping people overcome specific phobias. One exception is the use of benzodiazepines (antianxiety drugs) for some specific phobias. For example, people with flying phobias may use a benzodiazepine prior to boarding the plane. The benzodiazepine alone does not generally eliminate the phobia, but it does allow the person to fly.
More Information about Phobic Disorders
National Institute of Mental Health, Specific Phobia: General information on many aspects of specific phobias, including prevalence statistics