Most people have heard or know of PMS, but have you ever heard of PMDD? Premenstrual Syndrome, PMS, is the change in physical and emotional reactions that occur between ovulation and the start of one’s period for those that have a uterus. Symptoms usually present themselves in the form of cramping, mood swings, tender breasts, fatigue, cravings, etc. Not everyone experiences PMS, but most people have mild symptoms, while for others they can seem pretty intense. For a very small percentage of people, somewhere between 5%-8% of those with menstruation cycles, experience something much more intense. Premenstrual Dysphoric Disorder, or PMDD, is a very extreme and severe type of PMS.