Some women just “feel a little different” around the beginning of their menstrual cycle. This is called a catamenial symptom. These symptoms can include everything from cramping to headaches to acne to anxiety and are caused by changes in the hormone and biochemical levels in a woman’s body. But in some rare cases, this monthly change in body chemistry can cause severe and potentially dangerous reactions. Dr. Kirtly Parker Jones describes some of the more catastrophic things women experience during their cycle, what causes them and when to make an appointment with your doctor.