The abortion pills


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, 

The drug you’re referencing ‘RU-486’ is now named mifepristone and is one of two drugs used in medication abortions. It’s important to note that the legality of mifepristone is currently being challenged so depending on where you live it may not be available. Medication abortion refers to the procedure to terminate an early pregnancy (usually defined as within 70 days, or ten weeks, from the first day of the last menstrual period). This procedure typically involves taking both mifepristone and misoprostol. While these two medications are most frequently used in medication abortions, they may also be used to treat other ailments as well. Read on to learn more! 

To start, let's talk about how these drugs are used during a medication abortion procedure. Mifepristone is taken first; this medication works by blocking the hormone progesterone in the body, which causes the uterine lining to break down (without which the pregnancy can’t continue). After taking mifepristone—some people experience nausea or vaginal bleeding, however, this is relatively uncommon. Misoprostol—the second pill—can be taken right away or up to 48 hours later to trigger the uterus to empty, shedding the broken-down uterine lining in a process similar to a very heavy period or an early miscarriage. Many people experience cramping, heavy bleeding, and the passage of large blood clots and clumps of tissue that may be up to the size of a lemon. These symptoms usually start one to four hours after taking misoprostol and may last four to five hours or longer. Should these symptoms occur, it’s recommended to take some ibuprofen or acetaminophen (but not aspirin!) for pain management, use a heating pad or hot water bottle to soothe the cramps, grab some books or queue up a couple movies to pass the time, and reschedule other responsibilities for the day. Most people feel basically back to normal by the following day, with the possibility of a little cramping or tiredness. Medication abortion may also disrupt the menstrual cycle, but it typically goes back to normal within four to eight weeks. 

Medication abortions using the combination of these two drugs are very effective, though they do work better the earlier they’re taken in pregnancy: medication abortion is 98 percent effective if administered within the first eight weeks of pregnancy, 96 percent between weeks eight and nine, and 93 percent between weeks nine and ten of pregnancy. Terminating a pregnancy after week ten often requires an in-clinic abortion. While these two medications have undergone extensive safety testing, a health care provider may choose not to prescribe them if a person has any of the following conditions that increase the risk for adverse or life-threatening side effects: 

  • 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 intrauterine device (IUD), which would have to be removed prior to taking mifepristone 

List adapted from the U.S. Food and Drug Administration

The process of getting a medication abortion in the United States (US) has changed over time. The medications used in medication abortions are approved through the Food and Drug Administration’s Risk Evaluation and Mitigation Strategy (REMS), these drugs face certain restrictions on usage and prescription.  For most of the last two decades, medication abortions (specifically mifepristone) were required by the FDA to be administered in-person in a clinic or hospital setting by a certified medical provider; this restriction prevented access to medication abortion through telehealth appointments and through online and retail pharmacies.  Despite these limitations, research shows that medication abortions are no riskier to self-administer than many other widely available and self-administered prescription medications. In fact, the American College of Obstetricians and Gynecologists (ACOG), one of the leading organizations in reproductive health care in the country, petitioned the FDA to remove the in-person dispensing requirement, arguing that dispensing in-person didn’t improve reproductive health outcomes and put their patients at risk for exposure to COVID-19. In December 2021, the FDA officially revised their REMS restrictions to remove the in-person dispensing requirement; they also added a certification process for pharmacies wishing to dispense the medication. Even though the FDA has removed restrictions and cited the safety of these drugs, there are there are also court cases challenging the legality of mifepristone with some ruling it as illegal and others ruling it legal. Therefore, access to the drug may vary across the US. 

So, between the FDA REMS changes in and the striking down of Roe v. Wade in the Supreme Court, what does this mean for people seeking medication abortions? The short answer: it depends! The laws permitting the use of medication abortion and how it’s accessed vary widely by each state and are changing frequently. People living in states where abortions are banned or restricted may find assistance by visiting the Planned Parenthood website or AbortionFinder.org to help locate a clinic in a state where abortion is legal. The National Network of Abortion Funds website also helps connect low-income people with organizations providing financial assistance to cover the cost of the procedure or travel expenses. These state-level laws and FDA REMS might also change in the future, and some organizations such as Planned Parenthood and Guttmacher Institute are committed to compiling real-time information on state-specific policies that may be helpful in your planning and decision-making. 

In addition to being used for medication abortions, mifepristone and misoprostol are also used to help manage other ailments. Mifepristone may be used for patients with Cushing’s syndrome; research is still being conducted, but early results seem promising. Additionally, while the combination of mifepristone and misoprostol isn't recommended for ectopic pregnancies, mifepristone alone is an effective and low-risk treatment. Similarly, misoprostol also has other uses beyond medication abortions. For example, certain arthritis and pain medications (such as aspirin) can cause ulcers. Misoprostol, which has the ability to protect the stomach lining and decrease the amount of acid produced in the stomach, may be prescribed simultaneously with these pain medications to prevent ulcers from forming. 

As for your question about side effects, it may be useful to differentiate between the intended outcome of the medications (bleeding, cramping, and termination of pregnancy) from unwanted and unintended side effects, which may include nausea or vomiting, short-term fatigue or weakness, short-term fever or chills, tender breasts with a milky discharge, and a change in menstrual cycles for one to two months. The majority of these side effects typically resolve by themselves within one to two days. However, if vomiting, fever, heavy cramps, or heavy bleeding persist after 24 hours, it’s strongly recommended to seek medical attention since they may be a sign of a serious infection. Immediate medical attention is also advised for those who experience a high fever (100.4 degrees Fahrenheit) for four hours or longer, a fast heart rate, passing of large blood clots (bigger than a lemon) for more than two hours, heavy vaginal bleeding that soaks through more than two maxi pads per hour for more than two hours in a row, or fainting. Additionally, there are no known long-term impacts of medication abortion on fertility, future pregnancies, or risk of breast cancer. 

Overall, mifepristone and misoprostol may be used in combination to safely and effectively terminate an early pregnancy, as well as be used separately to treat or manage other ailments. For those who think they may be pregnant or are pregnant, there are many resources available. For more information about options, check out Pregnancy Options in the Go Ask Alice! archives. 

Hope this helps! 

Last updated Jul 21, 2023
Originally published Apr 27, 1995

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