- About 5% of women of reproductive age experience affective or physical premenstrual symptoms that markedly influence work, social activities, or relationships. Prospective charting of symptoms for at least two menstrual cycles is required to facilitate an accurate diagnosis of premenstrual syndrome or premenstrual dysphoric disorder. The optimal treatment plan begins with lifestyle modifications, followed by pharmacotherapy. Evidence from numerous controlled trials has clearly demonstrated that low-dose serotonin reuptake inhibitors, using intermittent or continuous administration, have excellent efficacy with minimal side effects. Modification of the menstrual cycle should be considered only after all other treatment options have failed.