Does Vilazodone Help With Antidepressant-associated Sexual Dysfunction?

Inclusion Criteria: 1. Patients must be able to understand the nature of the study, agree to comply with the prescribed dosage regimens, report for regularly scheduled office visits, and communicate to study personnel about adverse events and concomitant medication use; 2. Patients with major depressive disorder who are being treated with a selective serotonin reuptake inhibitor (citalopram, escitalopram, fluvoxamine, or paroxetine) or serotonin-norepinephrine reuptake inhibitor (desvenlafaxine, duloxetine, venlafaxine) for a minimum of 8 weeks. 3. The current episode of MDD is in remission (MADRS score \< 10 and CGI score of 1 or 2) 4. The duration of the current MDD episode is less than 2 years 5. Presence of antidepressant-associated sexual dysfunction (i.e., absence of sexual dysfunction prior to becoming depressed and presence of significant dysfunction while on the SSRI or SNRI despite being in remission from the depression). 6. Patient is at least 18 years old and not more than 65 years old 7. Patients must have the opportunity for sexual activity during the study period (in the form of availability of a suitable partner for sexual activity and/or openness to masturbation) 8. Patients must be willing to attempt some sexual activity (including masturbation) at least once every two weeks during the study Exclusion Criteria: 1. Patients who have previously failed to respond to or to tolerate either vilazodone or sertraline. 2. Patients with a history of severe discontinuation symptoms on tapering off the current antidepressant 3. Patients with other known causes of sexual dysfunction 4. Use of prohibited medications during the study period