Mifeprex (Medical Abortion Pill)

How Does the Abortion Pill Work?

The “Abortion Pill” is a regimen of two different drugs, mifepristone (branded Mifeprex, and also known as RU-486) and misoprostol, approved by the FDA for termination of pregnancy up to 70 days (10 weeks) gestation. The abortion pill typically costs $350-$650.

Mifepristone is a single pill taken to begin the medical abortion process. It functions as a progesterone antagonist, blocking the body’s natural pro-gestational hormone from getting to the baby. Without adequate progesterone, fetal development stops and the baby starves if it is small enough. The farther along in a pregnancy the woman is, the less likely it is that mifepristone will end the life of the baby.

Misoprostol is the second drug in the medical abortion process, typically administered 48 hours later. Misoprostol softens the cervix and causes uterine contractions to expel the contents of the uterus. If mifepristone has not ended the life of the baby, expelling it will. Passing the uterine contents typically occurs within a few hours or up to 2 weeks though bleeding may occur for up to two weeks.

The FDA requires a physical exam 7-14 days later to confirm complete abortion and ensure that there are no immediate complications.

Risks and Side Effects

As a general rule, the bigger the baby the riskier the abortion procedure, whether medical or surgical. The farther along in pregnancy, the greater the risk.

  • Common side effects include cramping, nausea, vomiting, diarrhea, heavy bleeding. In rare cases, serious infection and death can occur.
  • the procedure is unsuccessful <3.2% of the time prior to 57 days, 6.5% from 57-63 days, and 7.2% from 63-70 days gestation.1
  • Major adverse events requiring going to the emergency room occur for about 3.7% (about 1 in 25) of the patients between 47-63 days and 4.6% (about 1 in 20) of the patients between 64-70 days gestation.2
  • Not advised for women who have anemia, bleeding disorders, liver or kidney disease, seizure disorder, acute inflammatory bowel disease, use an intrauterine device (IUD), or are unable to return for the follow-up visit.

In addition to immediate complications, studies indicate that women who have had abortions may be at greater risk for future preterm births, infertility, breast cancer, sexual dysfunction and mental health diagnosis. See Abortion Risks and Side Effects for more.

Warnings and Off-Label Use

The FDA has approved the abortion pill under a strict Risk Evaluation and Mitigation Strategy (REMS), due to “serious and sometimes fatal infections and bleeding”3 Under the REMS, “Mifeprex may only be dispensed in clinics, medical offices, and hospitals by or under the supervision of a certified healthcare provider,” who “prescribes and who meets certain qualifications.”4

Some abortionists administer the abortion pill “off label,” or outside the parameters approved by the FDA. Some common examples are:

  • Medical abortion after 70 days gestation.
  • Administering misoprostol immediately after mifepristone or without mifepristone at all.

Both of these off-label uses are less effective for terminating pregnancy and carry greater risk for the pregnant woman than the FDA-approved regimen.

Abortion, COVID, and the Courts

In May 2020 the ACLU sued the FDA, petitioning the courts to remove the requirement that Mifeprex be dispensed in person during COVID-19. The FDA rule was blocked by lower courts, and as a result the abortion pill could be ordered, prescribed and delivered without a visit to a doctor for the latter half of 2020. However, on January 12, 2021 the Supreme Court overturned the lower court’s ruling, reinstating the FDA’s requirement for supervision by a certified healthcare provider.

Fetal Development Weeks 4-85

The following describes some of the developmental steps of the baby during the time frame when a woman is eligible for a medication abortion.

  • Nerves, brain and spinal cord begin to develop
  • Heart begins to beat
  • Eyes, arms, legs, lungs, and stomach begin to form
  • All organs are present by week 8

Abortion Pill Reversal

There is a 64-68% chance of continuing a healthy pregnancy if therapy is started within 72 hours of taking mifepristone. There is a greater chance of continuing a healthy pregnancy if therapy is received closer to when the mifepristone was taken. See Abortion Pill Reversal for details.

Medically Reviewed By:


1 Mifeprex (mifepristone) Label (2016), Table 4. Retrieved from

2 Winikoff B, Dzuba IG, Chong E, Goldberg AB, Lichtenberg ES, Ball C, et al. (2012). “Extending
outpatient medical abortion services through 70 days of gestational age.” Obstet Gynecol, 120(5): 1070-6.

3 Mifeprex (mifepristone) Label (2016). Retrieved from https://www.accessdata.fda.gov/drugsatfda_docs/label/2016/020687s020lbl.pdf

4 U.S. Food and Drug Administration (2018). Mifeprex (mifepristone) Information. Retrieved from https://www.fda.gov/drugs/postmarket-drug-safety-information-patients-and-providers/mifeprex-mifepristone-information

5 Mayo Clinic (2020). Pregnancy week by week. Fetal development: The 1 st Trimester. Retrieved from https://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/in-depth/prenatal-care/art-20045302

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