Mifepristone, also known as RU-486, is a medication typically used in combination with misoprostol to bring about an abortion during pregnancy. This combination is 97% effective during the first 63 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 birth defects if the pregnancy does not end. If used, appropriate follow up care needs to be available. Mifepristone is an antiprogestogen. It works by blocking the effects of progesterone, making the cervix easier to open, and promoting contraction of the uterus when exposed to misoprostol.
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 safest and most effective 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 generally costs more than US$200 for a course of treatment as of 2018, though this may range from US$110 to US$360.