How Medication Abortion Works and Why Its Safety Record Matters in Court

On September 28, 2000, the Food and Drug Administration approved a drug that had been known for years mostly by a laboratory code: RU-486. It had been developed in France in the early 1980s by the pharmaceutical company Roussel Uclaf and approved there in 1988. In the United States its path to approval ran through boycott threats, a manufacturer reluctant to sell it, congressional hearings and a long trial process run by a nonprofit that held the American rights. When approval finally came, the drug was given a brand name, Mifeprex, and a set of special restrictions few medicines carry. A quarter century later, its generic name, mifepristone, is one of the most litigated words in American law. What the drug does in the body, and what the research on it shows, turns out to be the center of those fights.

In short: Medication abortion uses two drugs, mifepristone and misoprostol, to end an early pregnancy, and it now accounts for most abortions in the United States. A large body of research shows serious complications are rare, and because courts and regulators weigh that evidence, its quality has become a legal battleground as much as a medical one. This post is general information, not medical advice.

What the two pills do

The regimen the FDA approved uses two medicines taken in sequence. This is a general description; anyone making a decision about their own care should rely on a licensed clinician and the FDA's official label.

The first drug, mifepristone, blocks progesterone, the hormone that maintains a pregnancy by supporting the lining of the uterus. Without progesterone's effect, the pregnancy stops developing and the lining begins to break down.

The second drug, misoprostol, is taken later, typically within a day or two according to the FDA label. It causes the cervix to soften and the uterus to contract, which expels the pregnancy, much like an early miscarriage. Cramping and bleeding are expected and can be heavy. A follow-up with a provider is part of the regimen to confirm that the process is complete.

Misoprostol has a history of its own. It was originally approved to prevent stomach ulcers in people taking certain anti-inflammatory drugs. It is widely used in obstetrics and gynecology for other purposes, including managing miscarriage and preventing bleeding after childbirth. The two-drug combination is also a standard treatment for early pregnancy loss, a fact that matters when states write laws restricting these drugs, because the same pills treat patients who are miscarrying.

When the FDA first approved mifepristone, it was for use through seven weeks of pregnancy. In 2016 the agency extended that to ten weeks, citing studies of effectiveness and safety in that window.

What the safety record shows

Here is where precision matters, because both sides of the legal fight cite numbers.

The FDA's label for mifepristone states that serious adverse reactions are rare. Major professional medical organizations, including the American College of Obstetricians and Gynecologists, describe medication abortion as safe and effective. Studies across many countries and millions of uses have found that serious complications, such as heavy bleeding requiring a transfusion or an infection needing hospital care, occur in a small fraction of cases, well under one percent in the large studies that have been published. The most common complication requiring further care is an incomplete abortion, which is usually managed with additional medication or a procedure.

The FDA has also tracked deaths among people who took the drug since its approval. The agency's own reports have shown a very small number, and in many of those cases the agency noted that the deaths could not be clearly attributed to the drug.

Medication abortion is not risk-free; no medicine is. Ectopic pregnancy, which is a pregnancy outside the uterus, is not treated by these pills and can be dangerous, which is why screening and follow-up matter. But the weight of the published research has been consistent for decades: compared with many common medications and with carrying a pregnancy to term, the risks are low.

The special rules the FDA attached

Most prescription drugs are approved with a label and left to doctors and pharmacists. Mifepristone came with extra conditions from the start. Those conditions are now organized under a program Congress authorized in 2007, called a Risk Evaluation and Mitigation Strategy, or REMS. The FDA can require a REMS for drugs whose benefits it believes outweigh their risks only if certain safeguards are in place. A relatively small number of drugs have one.

For mifepristone, the REMS has required that prescribers be certified, which means they attest that they can date a pregnancy, diagnose an ectopic pregnancy and arrange emergency care if needed. It has required patients to sign an agreement form. For years it also required that the drug be handed to the patient in person at a clinic, hospital or doctor's office, which kept it out of retail pharmacies and away from telehealth.

The in-person rule is the one that changed most. The FDA stopped enforcing it during the pandemic in 2021 and removed it in early 2023, while adding a new requirement that pharmacies dispensing the drug be certified. That opened the door to telehealth prescribing and mail delivery in states where abortion is legal.

Medical organizations, including the American College of Obstetricians and Gynecologists and the American Medical Association, have argued that the remaining REMS conditions are not supported by the evidence and should be lifted, pointing out that drugs with greater risks are prescribed without them. Opponents of abortion argue the opposite: that the rules were already too loose and should be tightened. Both sides frame the dispute in terms of safety evidence. That is why the evidence matters so much.

It is also worth knowing that the World Health Organization lists mifepristone and misoprostol on its Model List of Essential Medicines, the reference list countries use to decide which drugs a basic health system should have. Many countries allow the regimen under conditions as loose as or looser than those in the United States.

Why safety evidence ends up before judges

You might expect a question about drug safety to be settled by scientists at the FDA. In ordinary times, that is roughly how it works. The agency reviews trial data, approves a drug for specific uses, and keeps monitoring it. Courts usually defer to the agency's scientific judgment, because judges are not pharmacologists.

Mifepristone has not had ordinary times. Since Dobbs in 2022, opponents have tried to use the courts to restrict the drug nationally, even in states where abortion remains legal. Their argument has been that the FDA cut corners when it approved the drug in 2000 and when it eased restrictions in 2016 and 2021, and that the drug is less safe than the agency claimed.

To win that argument, they need evidence. And that is where the research itself became a battleground. In the case that reached the Supreme Court in 2024, a federal judge in Amarillo, Texas, cited studies that claimed higher rates of emergency room visits after medication abortion. In early 2024, the publisher of those studies retracted them, citing problems with the analysis and with undisclosed conflicts of interest among the authors. The authors disputed the retractions. The Supreme Court ultimately decided that case on standing without addressing safety.

Retractions are rare, and they are not the end of a debate; researchers can and do dispute them. But they are a signal that a journal no longer stands behind what it published, and a court relying on such work has a problem. The lesson for anyone following these fights is that the quality of studies is not a dry academic matter. When a court is asked to override a regulator, what counts as credible evidence becomes the whole case.

The strongest argument for more restriction, and a response

People who favor tighter rules make arguments worth stating fairly. They point out that the FDA stopped requiring prescribers to report non-fatal complications after 2016, which they say makes it harder to know how often problems occur. They worry that telehealth prescribing without an in-person exam could miss an ectopic pregnancy or misjudge how far along a pregnancy is. Some argue that because the drug is now taken largely at home, complications may show up in emergency rooms where they are not tracked as related to the drug.

Those concerns are about the quality and completeness of data, and they are legitimate questions to raise in a regulatory process. Here's my response, and it is an argument. Researchers have studied telehealth medication abortion directly, including large studies of patients in the United States who were screened by questionnaire rather than an in-person ultrasound, and have found effectiveness and safety outcomes comparable to in-person care. The FDA itself reviewed that kind of evidence before changing its rules. The question is not whether more data would be welcome; more data is always welcome. The question is whether a court should override the agency's judgment on the basis of studies that were later retracted, or whether the regulatory process, with its public comment and scientific review, is where those concerns belong. I think it plainly belongs in the second place.

Timing is part of the safety story

One reason medication abortion has such a strong safety record is when it happens. The federal Centers for Disease Control and Prevention collects abortion data from most states each year, and its reports have consistently shown that the large majority of abortions in the United States take place in the first trimester, most of them at nine weeks or earlier. Medication abortion is used almost entirely in that early window.

Early pregnancy care is, in general, safer than later care, for abortion and for other obstetric procedures alike. Anything that pushes a patient later, whether a waiting period, a long drive, a missed appointment or a legal ban that forces travel, tends to move care toward the point where risks are higher and fewer options remain. That is a point medical organizations have made repeatedly in court filings: restrictions sold as safety measures can produce the opposite effect by delaying care.

It also explains why the dispute over telehealth matters so much. A patient who can consult a clinician within days, rather than waiting weeks for an in-person appointment hundreds of miles away, is more likely to be within the window where medication abortion is most effective. Opponents respond that speed should not come at the expense of screening. That trade-off, between faster access and more in-person checks, is the real policy question, and it is one regulators are equipped to weigh.

What this means for patients now

As of 2026, medication abortion accounts for the majority of abortions in the United States, according to the Guttmacher Institute, which tracks abortion data nationally. Its share has grown steadily since 2000.

What a person can legally do depends on the state. In states that ban abortion, providing the drugs is generally illegal, and some states have added specific penalties or classified the drugs as controlled substances, as Louisiana did in 2024. In states that protect access, patients can often get a prescription through telehealth. Some states have passed shield laws to protect clinicians who prescribe across state lines, which has created its own legal clash.

None of this is legal or medical advice. If you or someone you care about is facing this decision, a licensed clinician and your state's official health department are the right sources. Many states and medical organizations publish information about where care is lawfully available. The FDA's own page on mifepristone contains the official label and the agency's safety information.

Health care, not a culture-war prop

It is worth stepping back from the courtroom. The two pills at the center of these fights are also used for people who are losing a pregnancy they wanted. Doctors in states with bans have described hesitating to give standard miscarriage care because of uncertainty about the law. Pharmacists have described questions about whether they may dispense misoprostol for ulcer patients. A legal fight about abortion has spilled into ordinary medicine.

That gives progressives a way to talk about this issue with neighbors who are not with them on abortion. A grandmother on an arthritis drug regimen, a woman miscarrying in a rural county two hours from a hospital, a family doctor afraid to prescribe what the textbooks call standard care: these are not abstractions, and most people, whatever they think about abortion, do not want them caught up in a legal fight.

What you can do

Medication abortion's future will be decided by evidence, regulators and lawmakers. Each of those is a place where you can contribute.

• Learn where the drug's legal status stands. The abortion pills and mifepristone page collects current reporting on lawsuits, state restrictions and FDA actions.
• Weigh in on the federal rules. When the FDA or another agency proposes changes affecting these drugs or insurance coverage for them, the proposal shows up on the public comment page, sorted by issue and closing date, along with tips on writing a comment that addresses the evidence.
• Follow the wider health fights. The health care for all page covers coverage, Medicaid and the policies that decide whether people in rural areas can reach a clinic at all.
• Reach the people who vote on these laws. The representatives lookup gives you your state legislators and members of Congress, with phone numbers, contact forms and their latest votes.