Premenstrual dysphoric disorder (PMDD) is a severe, sometimes disabling depressive disorder that occurs in the days leading up to the start of a woman's period. It is similar to premenstrual syndrome (PMS), but symptoms are more severe. The precise cause of PMDD is unclear, but it is thought to be related to hormonal changes. 

Symptoms of PMDD tend to start in the late phase of the menstrual cycle and end shortly after the start of menstruation, lasting an average of six days. Symptoms are predominantly emotional, such as depression, anxiety, problems concentrating, fatigue, and exaggerated changes of mood. Physical symptoms may include breast tenderness, abdominal bloating, headaches, and aches in other parts of the body. 

PMDD is often treated with cognitive behavioral therapy and medication to alleviate the more severe and debilitating symptoms. Dietary and lifestyle changes may also be recommended, such as getting more exercise, cutting down on caffeine and stopping smoking. Drug classes commonly prescribed to treat PMDD are selective serotonin reuptake inhibitor antidepressants, SSRIs, and some monophasic contraceptives.