Mifepristone: What to know about the drug in the Supreme Court's abortion pill case

Mifepristone is one pill in a two-pill regimen approved to induce a medication abortion, which uses drugs, rather than a medical procedure, to end a pregnancy. Medication abortions can take place in a clinic under a doctor's supervision, but they're also a safe and rigorously tested method for self-managed abortion 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. 

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

The two-pill regimen involves taking mifepristone by mouth, 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. Mifepristone blocks the hormone progesterone, which the body needs to maintain a pregnancy, and misoprostol induces contractions that empty the uterus. 

(Misoprostol, which is also used to treat other, non-pregnancy-related conditions, is not as tightly regulated as mifepristone, and its regulation has not been challenged in court.)

In the U.S., two-pill medication abortions can be used to end a pregnancy through 10 weeks gestation, or up to 70 days from the first day of a person's last menstrual period. Mifepristone should not be used in cases of ectopic pregnancy, in which a fertilized egg implants outside the uterus, and people with intrauterine devices (IUDs) should have these devices removed before taking the pills, the FDA cautions. The pills can also be used in the treatment of pregnancy loss.

Misoprostol can be used without mifepristone to safely induce abortion. However, the two-pill regimen is preferred because people tend to experience milder side effects when taking both, and studies suggest taking both pills is more effective. Taking misoprostol alone tends to result in more nausea, vomiting and diarrhea and a longer period of cramping and bleeding. 

Studies show that the two-pill medication abortion regimen that includes mifepristone is very safe and effective.

According to the KFF, studies suggest 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%.

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 10 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 certified health provider at a specialized clinic. The FDA also now allows certified pharmacies to dispense the pill to people with a prescription, following a regulatory change made in 2023. 

SCOTUS heard a case about mifepristone because the pill had been challenged in several lower courts. 

The pill was first challenged in April 2023, when a federal district judge in Texas ruled that the FDA's approval of mifepristone in 2000 was unlawful and should be suspended. The judge's ruling would have taken 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 the Texas ruling, the U.S. Department of Justice filed an appeal and called for an immediate stay of the decision. Meanwhile, the FDA appealed the decision, and the 5th Circuit Court of Appeals then ruled that mifepristone's long-standing approval should be left alone. 

However, the appellate court argued that the FDA's regulatory changes in 2016 and 2021 should be rolled back. This change would have reinstated the requirement for patients to receive the pill in person from a certified doctor, thus stopping nurse practitioners, physician assistants and pharmacies from dispensing the drug in person or via mail. 

Both the plaintiffs (anti-abortion groups) and the defendant (the FDA) appealed the court's rulings.

Starting on March 26, 2024, the Supreme Court began reviewing the appellate court's decision in a case called "FDA v. the Alliance for Hippocratic Medicine" (AHM). AHM is a collective of anti-abortion groups that includes doctors. 

SCOTUS said it would not review the FDA's original approval of mifepristone. Rather, it would first address the question of whether AHM had legal standing to sue the FDA over its regulation of the pill. 

AHM argued it did because its members may end up treating patients experiencing side effects of the drug, which could divert resources from their other patients. In addition, treating the patients would violate the doctors' moral stances around abortion, the plaintiffs said.

On June 13, SCOTUS ruled that AHM did not have legal standing and thus ended the case.