Although it’s referred to as a pill (singular), the abortion pill actually consists of two medications: mifepristone and misoprostol.
Mifepristone is taken first, usually in a clinic. This medication cuts the supply of the hormone progesterone to the embryo, which is needed to maintain the pregnancy. Without a steady supply of progesterone, the embryo stops growing.
Misoprostol is taken 24-48 hours later at home. This medication causes the uterus to contract and expel the embryo, which ends the pregnancy.