As a selective serotonin reuptake inhibitor, Lexapro^® (escitalopram oxalate) can help treat the symptoms of depression and generalized anxiety disorder. This prescription medication works by altering the levels of serotonin in the brain. Lexapro comes in the form of a tablet or a liquid and is typically taken once a day. While most people tolerate this drug well, side effects can occur with Lexapro, including nausea, insomnia, and headaches. Before your healthcare provider prescribes Lexapro, he or she will consider several factors, such as your age, other medical conditions you have, and other medications you may be taking.