Under the brand names Paxil, Pexeva, and Brisdelle, paroxetine is a selective serotonin reuptake inhibitor (SSRI) that is prescribed for several mental health issues. These consist of post-traumatic stress disorder (PTSD), obsessive-compulsive disorder (OCD), depression, and anxiety disorders. To properly manage expectations and treatment plans, patients and healthcare providers must be aware of how long this medication takes to work.