Sertraline is used to treat depression, obsessive-compulsive disorder (bothersome thoughts that won't go away and the need to perform certain actions over and over), panic attacks (sudden, unexpected attacks of extreme fear and worry about these attacks), posttraumatic stress disorder (disturbing psychological symptoms that develop after a frightening experience), and social anxiety disorder (extreme fear of interacting with others or performing in front of others that interferes with normal life). It is also used to relieve the symptoms of premenstrual dysphoric disorder, including mood swings, irritability, bloating, and breast tenderness. Sertraline is in a class of antidepressants called selective serotonin reuptake inhibitors (SSRIs). It works by increasing the amounts of serotonin, a natural substance in the brain that helps maintain mental balance.