Mifepristone

Mifepristone, also known as RU-486, is a medication typically used 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. Two weeks after use effectiveness should be verified. 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, a malformed baby if the pregnancy does not end. If used appropriate follow up care needs to be available. It works by blocking the effects of progesterone. and causing contractions of the uterus.

Mifepristone was developed in 1980 and come into use in France in 1987. It became available in the United States in 2000. It is on the WHO Model List of Essential Medicines, the most important medications needed in a basic health system. As of 2014 it is not easily available in either Canada or Australia. Cost and availability limits access in many parts of the developing world. In the United States it costs more than US$200 ($200 in 2016) a dose.