Symptoms include either extreme anxiety and fear associated with the object or situation or avoidance. To be diagnosed, the symptoms must be disruptive to everyday functioning (such as quitting a great job merely because you have to use an elevator).
Treatment is often behavioral in nature, with the therapist guiding the client through exercises more closely resembling the feared object or situation. Exploring underlying issues can also be beneficial.
Prognosis is very good if treated effectively.