The abortion pill (mifepristone)


I remember reading about RU-486. Could you explain how it works and what, if any, side effects are linked to it? Thank you.

— Options

Dear Options,

Medication abortions (sometimes referred to as abortion pills) provide people with an alternative to in-clinic abortions in early pregnancies, using mifepristone (formerly known as RU-486). In this case, early pregnancy means within 70 days (ten weeks) from the first day of the last menstrual period. This drug works by blocking the hormone progesterone, causing the uterine lining to break down, without which the pregnancy cannot be maintained. Mifepristone is usually combined with misoprostol, a low-dose synthetic prostaglandin (a chemical substance found in the body) that causes the uterus to empty. Medication abortions are very effective, inducing a complete early abortion with a 93 percent success rate for those nine to ten weeks pregnant, 96 percent for those eight to nine weeks pregnant, and 98 percent for those eight weeks pregnant or less. Though those who choose this method may experience acute side effects, there are no known negative long-term effects on sexual and reproductive health due to mifepristone use.

As per the Food and Drug Administration (FDA) ruling, people interested in getting a medication abortion receive a medication guide that details who may and who may not use the drug and its potential side effects. For safety reasons, a health care provider may choose not to prescribe it if a person has any of the following conditions:

  • A history of ectopic pregnancy
  • Adrenal gland issues
  • A history of long-term corticosteroid therapy
  • An allergy to mifepristone, misoprostol, or similar drugs
  • Bleeding problems or current use of anticoagulant drugs
  • Inherited porphyria (a disorder that affects red blood cells)
  • Having an intraunterine device (IUD), which would have to be removed prior to taking mifepristone

List adapted from FDA.gov.

Eligible people who choose a medication abortion are required to visit a specially trained health care provider. Why? In the event that the combination of drugs doesn't produce a complete abortion, these providers are equipped to provide a follow-up suction procedure. There are four steps for a medication abortion:

  1. First, a visit with a health care provider is necessary to discuss options, get a physical, and have lab tests. This is also an opportunity to talk with them about any other current medications (especially anticoagulants), dietary supplements, or allergies that might interact with mifepristone.

  2. The second step is to take the mifepristone pills, along with some antibiotics to prevent infection. This step is typically done in the presence of a health care provider.

  3. One to three days after mifepristone is taken, misoprostol (per a health care provider's instructions) is then taken, which initiates the emptying of the uterus.

  4. Within two weeks of taking misoprostol, a follow-up appointment is needed to be sure the abortion is complete and there are no complications. The patient may be asked to have an ultrasound or blood tests. It's possible to get pregnant right after a medication abortion, so this may be a good time to discuss birth control options with the health care provider.

Options, to answer your question about side effects: bleeding and cramping usually begin after taking misoprostol, though for some people, bleeding begins after taking mifepristone. It may help to wear pads instead of tampons during the process to track bleeding and it’s common to see large blood clots. Other side effects of the drug combination may include nausea, dizziness, mild fever or chills, vomiting, short-term fatigue or weakness, and occasional diarrhea. It’s also helpful to avoid grapefruit juice as it may interfere with the effectiveness of the drugs. Some might experience discomfort (including side effects such cramping and tender breasts with milky discharge) for 24 hours after taking misprostol, but if nausea, cramps, diarrhea, or fever is still being experienced after that point, it’s best to seek medical attention as soon as possible rather than wait for the two-week follow-up appointment. Immediate medical attention is essential if a person experiences a high fever (100.4 degrees Fahrenheit for four hours or longer), chills, fast heart rate, severe pain below the waist, or fainting. Note that bleeding may last a while (9 to 16 days, but sometimes 30 days or longer) after having a medication abortion. Other potential complications include an unterminated pregnancy, uterine blood clots, excessive bleeding, allergic reaction, and infection.

Though a potentially uncomfortable process, it's considered low risk and there are ways to lessen the unpleasant side effects. Taking ibuprofen or acetaminophen often provides relief, but avoiding aspirin is advise because of risk of excess bleeding. For a few days afterwards, it’s best to refrain from strenuous physical activity as the body continues to recover. In addition to plenty of rest, back rubs, showers, heating pads, and wearing supportive bras after the process may help. Sexual activity may be resumed as soon as a person feels ready. Though it may take four to eight weeks for a person’s period to return to its typical cycle, mifepristone isn't known to negatively impact future pregnancies or increase risk of breast cancer.

One key detail to note is that once started, the process can't be reversed. Some groups claim to be able to reverse abortions if the misoprostol hasn't yet been taken, but there is no evidence to indicate that any treatments can reverse the effects of the mifepristone.

A quick note: mifepristone is often confused with emergency contraception (EC but also often known as "the morning after pill"). However, they're not the same. Mifepristone is used after it’s confirmed that a person is already pregnant. EC is available to people who've had unprotected sex and are concerned that they could become pregnant. EC is hormonal medication that's taken within 120 hours (five days) of sex and acts to prevent pregnancy. Likewise, a copper IUD (such as ParaGard) may be used as emergency contraception if it’s inserted within 120 hours after unprotected sex. If a person is already pregnant, emergency contraceptives don't end the pregnancy.

There are many resources available for those who think they may be pregnant or are pregnant. For more information about options, check out Pregnancy Options in the Go Ask Alice! archives. Planned Parenthood also offers information and resources related to sexual and reproductive health. In addition to potentially being a physically taxing process, for some, a medication abortion may be an emotional experience as well — so, some may find it helpful to have a loved one for support or to consult a mental health professional throughout the process. There also some hotlines that can provide support with abortion, such as Exhale and All-Options.

Hope this helps!

Last updated Mar 01, 2018
Originally published Apr 27, 1995

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