Mifepristone, also known as RU-486, is a medication typically used in combination with misoprostol, to bring about an abortion. This combination is more than 95% effective during the first 50 days of pregnancy. It is also effective in the second trimester of pregnancy. Effectiveness should be verified two weeks after use. It is taken by mouth.
Common side effects include abdominal pain, feeling tired, and vaginal bleeding. Serious side effects may include heavy vaginal bleeding, bacterial infection, and a malformed baby if the pregnancy does not end. If used, appropriate follow up care needs to be available. Mifepristone is an antiprogestogen and works by blocking the effects of progesterone and causing contractions of the uterus.
Mifepristone was developed in 1980 and came into use in France in 1987. It became available in the United States in 2000. It is on the World Health Organization’s List of Essential Medicines, the most effective and safe medicines needed in a health system. Mifepristone was approved by Health Canada in 2015 and became available in Canada in January 2017. Cost and availability limits access in many parts of the developing world. In the United States it costs more than $200 a dose.