Anxiety disorders are the most common mental illnesses in America. More than 19 million U.S. adults are affected by these debilitating illnesses each year. Children and adolescents can also develop anxiety disorders. There are several types of anxiety disorders, such as obsessive-compulsive disorder, post-traumatic stress disorder, and agoraphobia. Each anxiety disorder has its own distinct features, but they are all bound together by the common theme of excessive, irrational fear and dread. Possible treatment options can include medication, psychotherapy, or a combination of both.