What do we know about mifepristone, the abortion pill facing a potential Supreme Court ruling?

close up of a orange box labeled "the early option pill Mifeprex"
Mifepristone's approval has been challenged by a federal judge in Texas. (Image credit: ROBYN BECK / Contributor via Getty Images)

The fate of the abortion pill mifepristone, approved by the U.S. Food and Drug Administration (FDA) more than 20 years ago, will likely soon be pushed into the hands of the Supreme Court. 

Here's what you need to know about mifepristone and about the recent federal court rulings that could put the drug's approval up for debate.

Related: State abortion bans may limit access to drug used to treat lupus and cancer 

What is mifepristone? 

Mifepristone is one pill in a two-pill regimen approved to induce a medication abortion, sometimes called a "medical" abortion. Medication abortion is a safe and rigorously tested method for self-managed abortion, meaning an abortion induced outside a medical setting, Dr. Melissa Simon, a professor and obstetrician-gynecologist at the Northwestern University Feinberg School of Medicine in Chicago, previously told Live Science.

The two-pill regimen involves taking mifepristone orally, waiting 24 to 48 hours, and then taking the second pill — misoprostol — by placing it in the vagina, under the tongue or in the cheek, according to the World Health Organization (WHO). Mifepristone blocks the hormone progesterone, which the body needs to maintain a pregnancy, and misoprostol then induces contractions that empty out the uterus. 

(Note that misoprostol can be used in isolation to safely induce abortion, without the need for mifepristone. However, the two-pill regimen is preferred because people tend to experience milder side effects when taking both pills, NPR reported. Taking misoprostol alone tends to result in more nausea, vomiting and diarrhea and a longer duration of cramping and bleeding. Studies also suggest that the two-pill regimen is more effective than misoprostol alone, CNN reported.)

The two-pill medication abortion regimen can be used to end a pregnancy through ten weeks gestation (70 days or less since the first day of a person's last menstrual period), according to the FDA. Mifepristone should not be used in cases of ectopic pregnancy, where the fertilized egg implants outside of the uterus, and people with intrauterine devices (IUDs) should have these devices removed before taking the pills, the FDA cautions. 



—Abortion laws by state: https://reproductiverights.org/maps/abortion-laws-by-state/

—For questions about legal rights and self-managed abortion: www.reprolegalhelpline.org 

—To find an abortion clinic in the US: www.ineedanA.com

—Miscarriage & Abortion Hotline operated by doctors who can offer expert medical advice: Available online or at 833-246-2632

—To find practical support accessing abortion: www.apiarycollective.org 

The FDA first approved Mifeprex, a brand name version of mifepristone, for use in 2000. The pill was initially approved for use through seven weeks gestation, and then in 2016, the FDA extended its approval to ten weeks. The agency approved a generic version of Mifeprex in 2019. And as of 2021, the agency has allowed people to receive medication abortion pills by mail after a telemedicine appointment, rather than needing to get them in person from a health provider at a specialized clinic.

Studies show that this two-pill medication abortion regimen is remarkably safe and effective. According to the Kaiser Family Foundation, medication abortion successfully terminates the pregnancy 99.6% of the time, with a 0.4% risk of major complications and an associated mortality rate of less than 0.001%

(For comparison, the risk of death from the antibiotic penicillin is four times higher than that, and the risk of death from Viagra is nearly 10 times higher, CNN reported.)

A combination of mifepristone and misoprostol can also be used in the treatment of miscarriages, according to NPR. Mifepristone is also FDA-approved for the treatment of Cushing syndrome, a condition where the body makes too much of the stress hormone cortisol, and the drug is sometimes used off-label to treat uterine leiomyomas, also called fibroids, according to the medical resource StatPearls.

Why is mifepristone's approval being challenged? 

Demonstrators gather in front of the U.S. Supreme Court as the justices hear arguments in Dobbs v. Jackson Women's Health, a case about a Mississippi law that bans most abortions after 15 weeks, on December 01, 2021 in Washington, DC.

Demonstrators pictured in front of the U.S. Supreme Court as the justices heard arguments in Dobbs v. Jackson Women's Health in December 2021 in Washington, DC.  (Image credit: Chip Somodevilla / Staff via Getty Images)

Mifepristone's longstanding approval was challenged on Friday (April 7) when U.S. District Judge Matthew Kacsmaryk of Texas issued a preliminary ruling that the FDA's approval of the drug in 2000 was unlawful and should be suspended. Kacsmaryk issued a "nationwide injunction," meaning his ruling would take effect across the entire country unless a higher court issued a stay, or an order to halt the legal proceeding. 

On the same day as Kacsmaryk's ruling, the Department of Justice filed an appeal and called for an immediate stay of the decision

Also on Friday, a federal judge in Washington State — Judge Thomas O. Rice — issued a ruling that directly opposes Kacsmaryk's, stating that the FDA should not make any regulatory changes that would further restrict access to mifepristone. (Rice's ruling applies to 17 states and Washington D.C., whose attorneys general recently filed a lawsuit arguing that the FDA's current regulations on mifepristone are overly burdensome. Rice did not call for the FDA to overturn those existing regulations, but he did rule that the agency shouldn't place any additional restrictions on the drug.)

These contradictory rulings from Texas and Washington could soon propel the mifepristone debate to the Supreme Court. The Supreme Court's decision would likely not only affect the abortion pill's standing, but also the FDA's congressionally granted authority to approve and regulate medications, The New York Times reported.     

Nicoletta Lanese
Channel Editor, Health

Nicoletta Lanese is the health channel editor at Live Science and was previously a news editor and staff writer at the site. She holds a graduate certificate in science communication from UC Santa Cruz and degrees in neuroscience and dance from the University of Florida. Her work has appeared in The Scientist, Science News, the Mercury News, Mongabay and Stanford Medicine Magazine, among other outlets. Based in NYC, she also remains heavily involved in dance and performs in local choreographers' work.