CELEXA is a selective serotonin reuptake inhibitor (SSRI). This antidepressant medicine has been used safely and effectively by more than 40 million patients worldwide. Lexapro was developed by isolating the medicinal component of CELEXA® (citalopram HBr), a molecule known as an isomer. As a result, Lexapro is able to provide effective and well-tolerated therapy for patients. Close Window