Originally approved by the Food and Drug Administration for the treatment of tuberculosis, D-cycloserine (Seromycin) may be the next line of defense in phobia treatment. The antibiotic has been found to aid in the treatment of a variety of simple phobias, including the fear of spiders (arachnophobia) and a fear of heights (acrophobia). The drug is not helpful as a sole treatment, however, and works as an adjunct to exposure therapy in patients with phobias. Repeated clinical trials have demonstrated that patients with acrophobia (fear of heights) who receive exposure therapy, and who also took D-cycloserine, learn to override their fears more quickly than those who took a placebo. Exposure therapy, which is often used in the treatment of anxiety disorders, targets learned behaviors that people engage in (most often the avoidance) in response to situations or thoughts and memories that are viewed as frightening or anxiety-provoking.