Premenstrual Stress Syndrome (PMS, also called Premenstrual Stress, Premenstrual Tension, PMT, Premenstrual Syndrome, Periodic Mood Swing) is stress which is a physical symptom prior to the onset of menstruation. It is characterized by symptoms of mood swings, depression, anxiety and irritability that occur prior to menses, usually in the two week period between ovulation and menses. It is sometimes accompanied by physical symptoms such as bloating and cramping. It has been suggested that PMS might be a socially constructed disorder. Evidence supporting this view comes from medical trials that show placebo drugs may work as well as pharmaceuticals in providing relief. The social construct hypotheses remain controversial.