Norethindrone is used to treat endometriosis, a condition in which the type of tissue that lines the uterus (womb) grows in other areas of the body and causes pain, heavy or irregular menstruation (periods), and other symptoms. Norethindrone is also used to treat abnormal periods or bleeding and to bring on a normal menstrual cycle in women who menstruated normally in the past but have not menstruated for at least 6 months and who are not pregnant or undergoing menopause (change of life). Norethindrone is also used as a test to see if the body is producing certain female hormones (natural substances that affect the uterus). Norethindrone is in a class of medications called progestins.