Overview: Mifepristone is an oral tablet used to end a pregnancy during the first 10 weeks of pregnancy. Mifepristone works by blocking a hormone needed to maintain a pregnancy. Common side. Mifeprex selectively blocks progesterone via the progesterone receptor at low doses and when used to terminate a pregnancy, Mifeprex works by competing with progesterone at progesterone-receptor sites. Mifepristone is used in combination with misoprostol (Cytotec ®) to end an early pregnancy. Mifepristone is in a class of medications called antiprogestational steroids. It works by blocking the activity of progesterone, a substance your body makes to help continue pregnancy. What is mifepristone and how does it work? Mifepristone is a drug that blocks a hormone called progesterone that is needed for a pregnancy to continue. Following use by 34,000 women in France from April 1988 to February 1990 of mifepristone distributed free of charge, Roussel-Uclaf began selling Mifegyne (mifepristone) to hospitals in France in February 1990 at a price (negotiated with the French government) of US$48 (equivalent to $118.29 in 2025) per 600-mg dose. Mifepristone (Mifeprex) is an oral tablet that may be used with misoprostol tablets to end a pregnancy that is 10 weeks or less (70 days or less since the start of your last period). The “abortion pill” is the popular name for a safe and effective way to end an early pregnancy using a combination of two medicines: mifepristone and misoprostol. Mifepristone stops the pregnancy from growing. After taking mifepristone, you take a second medicine (misoprostol) up to 48 hours later. Mifepristone is used in a regimen together with misoprostol to end a pregnancy that is less than 70 days in duration. It works by stopping the supply of hormones that maintains the interior of the uterus. MIFEPREX™ (mifepristone) Tablets, 200 mg For Oral Administration Only If Mifeprex* results in incomplete abortion, surgical intervention may be necessary. Prescribers should determine in advance whether they will provide such care themselves or through other providers. Prescribers should also give patients clear instructions on whom to call and what to do in the event of an emergency. Mifepristone, also called “the abortion pill,” is a U.S. FDA-approved oral medication used—along with misoprostol—in a two-drug regimen to end a pregnancy up to 70 days into gestation.