PMDD (Premenstrual Dysphoric Disorder) is a severe form of PMS where hormonal changes in the luteal phase of the menstrual cycle trigger intense emotional and physical symptoms. It can cause significant mood shifts such as depression, anxiety, irritability, and fatigue that typically appear in the one to two weeks before a period and improve once bleeding begins. It is a recognised medical condition and not a personality flaw or “just bad PMS”, and it can have a major impact on daily life.