People take for granted. Lexapro is used to treat anxiety and major depressive disorder. Because Escitalopram appears to relieve depression by increasing serotonin levels with minimal effect on many of the other chemicals in the brain believed to influence mood. Lexapro works by increasing the available supply of serotonin. Lexapro blocks the re-absorption of serotonin by the first nerve cell. Lexapro is an antidepressant in a group of drugs called selective serotonin reuptake inhibitor. As indicated in the prescription of your doctor.