The medication in this study is a serotonin reuptake inhibitor (SSRI), a class that is considered the first-line treatment for severe PMS at this time. Although data indicate that young women who have PMS in their teen years report the same symptoms and symptom severity as adult women, clinical trials have not included this age group, and there is no information on the efficacy and safety of treatment with a serotonergic antidepressant for PMS in teens.