Hi, Mirena contains the hormone progestin which helps in contraception by changing the vaginal and cervical secretions into thick thereby preventing the movement of the sperm into the vagina to fertilize the egg, prevents the uterine changes to accommodate the fertilized egg during conception and partially by preventing ovulation that is release of egg. Mirena has muscle relaxing properties thereby slowing the movements of the gut causing constipation. If the symptoms is mild, high fibre diet and plenty of fluids helps to relieve the condition. If the symptoms are severe, medication is necessary for normal daily activities. If the symptoms persists even after medication, alternative contraceptive methods are advised. Discuss with your gynecologist for further management. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Pradeepraj, General & Family Physician