Hi, Synron N is synthetic oral progestin used for heavy menstrual bleeding, pain during menstruation, endometriosis, amenorrhea, preventing unwanted pregnancy, acts as birth control, breast cancer etc. Some of the common side effects are irregular menstrual periods, enlargement of breasts, stomach pain, weight loss, blurred vision, headache, chest pain, difficulty in swallowing, nausea, vomiting, weight gain, fluid retention, spotting, jaundice, change in speech or senses like hearing, smell, taste, touch etc. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Zubayer Alam, General and Family Physician,