A member of the family of medications known as selective serotonin reuptake inhibitors (SSRIs), Celexa is indicated for the treatment of depression in adults. SSRIs help restore the brain's chemical balance by increasing the available supply of serotonin, a substance in the brain believed to influence mood. Celexa had been the fastest-growing SSRI in the United States prior to the availability of Forest's newer SSRI antidepressant, Lexapro.