Lexapro is used to treat depression. In the brain that may become unbalanced and cause depression or anxiety. If left untreated, can cause major problems in your life. Lexapro is an antidepressant in a group of drugs called selective serotonin reuptake inhibitor used to treat depression. Evidence suggests an imbalance of serotonin, a chemical messenger in the brain that may become unbalanced and cause depression or anxiety. Do have problems note that they are much less severe than they were on older anti-depressants. Escitalopram helps to restore the brain's chemical balance by increasing the amount of serotonin, a natural substance in the brain that may become unbalanced and cause depression or anxiety.