Mifepristone

Is mifepristone safe?

As a medicine, mifepristone has a well-documented safety record: in clinical studies of 30,966 women summarised in the US label, serious adverse reactions occurred in under 0.5%. The main risks are prolonged heavy bleeding and, very rarely, serious infection, which is why the label carries a boxed warningBoxed warningThe strongest safety warning the US FDA puts on a medicine's label, printed inside a black border at the top.More in the glossary. We score it 76, close to the combined pill (77). The rating covers drug safety only, not the legal or ethical questions around its use.

The US label regimen for ending an intrauterine pregnancy through 70 days is one 200 mg tablet by mouth, followed 24 to 48 hours later by 800 mcg of misoprostol placed in the cheeks. A follow-up 7 to 14 days later confirms the result. In US trials of 16,794 women the regimen worked without a procedure in 97.4% of cases; 2.6% needed surgical intervention, including 0.7% with an ongoing pregnancy. Success falls as pregnancy advances, from 98.1% before 49 days to 92.7% at 64 to 70 days.

Availability and the rules for prescribing it vary widely between countries and, in the US, between states. This page does not cover how to obtain it; talk to a doctor or pharmacist about what applies to you.

How common are serious side effects?

Bleeding and cramping are the expected effects of the treatment. Bleeding or spotting lasts 9 to 16 days on average, and up to 8% of people have some bleeding for 30 days or more. Nausea, weakness, fever or chills, vomiting, headache, diarrhoea and dizziness are each reported by more than 15%, mostly linked to misoprostol.

The label's figures for serious events, from US and non-US studies:

Event	US studies	Non-US studies
Blood transfusion	0.03% to 0.5%	0% to 0.1%
Sepsis	0.2% (one study, 629 women)	under 0.01%
Hospital admission	0.04% to 0.6%	0% to 0.7%
Emergency room visit	2.9% to 4.6%	0% (one small study)

Population data give a similar picture. In Ontario, where mifepristone has been available with a normal prescription since 2017, a 2022 NEJM study found severe adverse events in 0.03% of abortions before it was available and 0.04% after. A 2023 study in the Annals of Internal Medicine found serious adverse events in 3.3 per 1,000 women after mifepristone with misoprostol, against 1.8 per 1,000 after procedures in outpatient clinics; the authors concluded that adverse events were rare but more likely after the medication route, mostly the less serious ones.

The FDA's post-marketing summary counted 32 deaths among an estimated 5.9 million US users from 2000 to 2022, listed regardless of whether the drug caused them; 11 were linked to sepsis. The same summary records 4,218 reports of any adverse event over that period. The FDA notes that since 2016 prescribers no longer have to report non-fatal serious events to the manufacturers, which limits these counts.

Who should not take it

The label lists these contraindicationsContraindicationA situation in which a medicine should not be used, because the risk clearly outweighs any benefit, such as a known allergy to it.More in the glossary: a confirmed or suspected ectopic pregnancy (the drug does not treat it), an IUD in place, chronic adrenal failure, long-term corticosteroid treatment, bleeding disorders or anticoagulant treatment, inherited porphyria, and allergy to mifepristone, misoprostol or other prostaglandins. Because some symptoms of a ruptured ectopic pregnancy resemble an expected medical abortion, the label asks clinicians to stay alert to it even after an ultrasound.

Mifepristone is broken down by the liver enzyme CYP3A4CYP450 enzymesA family of liver enzymes that break down many medicines. When another drug or supplement speeds them up or slows them down, drug levels change.More in the glossary. Rifampin, dexamethasone, St John's wort and some anti-seizure drugs may lower its levels; ketoconazole, itraconazole, erythromycin and grapefruit juice may raise them. It is slowly eliminated, so it can raise levels of other CYP3A4 drugs for some time. Tell the prescriber about every medicine you take.

The FDA review and the court cases

Mifepristone is sold in the US under the Mifepristone REMS Program. Since the January 2023 modification, certified prescribers can prescribe it, certified pharmacies can dispense it, and it may be dispensed in person or by mail.

In September 2025 the FDA began a review of mifepristone. In a letter of 11 December 2025 to Senator Bill Cassidy, FDA Commissioner Marty Makary wrote that the review is informed by "the lack of adequate consideration underlying the prior REMS approvals" and by recent studies raising safety concerns. On 30 September 2025 the FDA also approved a third US maker, Evita Solutions.

The main court case is Louisiana v. FDA, filed in October 2025. Louisiana argues that the 2023 REMS changes rest on inadequate data and undermine its laws; the manufacturers Danco and GenBioPro, which joined as defendants, argue among other things that the state lacks standing. On 7 April 2026 the district court paused the case for the FDA review. On 1 May 2026 the Fifth Circuit reinstated in-person dispensing nationwide, and on 14 May 2026 the Supreme Court stayed that order while the case continues, with Justices Thomas and Alito dissenting. The Fifth Circuit heard argument on 9 September 2026.

In its 7 October 2026 status report, the FDA said it expects to finish a safety study by mid-December 2026 and to report no later than March 2027. Americans United for Life, which opposes abortion, criticised the timeline; the Center for Reproductive Rights, which supports access to abortion, has called the review politically motivated. Rules may change after this page was updated.

How we scored it

Dependence (95), overdose marginOverdose marginHow far a normal dose is from a harmful one. A wide margin means an accidental extra dose is unlikely to cause serious harm.More in the glossary (90) and track record (92) are strong: it is a single dose with a wide margin and 26 years of US data. Serious side effects (66) reflect bleeding, rare severe infection and the need for a procedure in about 3%. Regulatory warnings (35) is the weakest factor because of the boxed warningBoxed warningThe strongest safety warning the US FDA puts on a medicine's label, printed inside a black border at the top.More in the glossary and the REMS. Questions about whether the treatment is right for you belong with your doctor or pharmacist.