Lexapro^® (escitalopram oxalate) is a prescription medication that is approved to treat the symptoms of depression and generalized anxiety disorder. The drug works by allowing a certain brain chemical (serotonin) to stay in the brain for a longer period of time. Side effects of Lexapro may include headaches, nausea, and insomnia. In order for Lexapro to work properly, you must take it as prescribed. Typically, Lexapro is taken by mouth once a day. If you do not take your Lexapro as scheduled, take your missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule. Do not double your dose of Lexapro.