Here’s How Abortion Pills Work – and Why We Need Them

Ari Cofer Fact Checked
illustration of woman holding abortion pills
UW Medicine / Ada Love

As safe access to abortion continues to be debated in the United States, there’s a lot of misunderstanding surrounding how abortions work. The use of medical abortions (medication abortions), or the “abortion pill,” is an effective way to end pregnancies up to 11 weeks’ gestation. 

Medication abortions make up more than half of all abortions, especially, currently, with access to abortions dwindling around the country.  

What are medication abortions? 

“Medication abortion in the United States involves two pills, mifepristone and misoprostol,” says Dr. Emily Godfrey, an associate professor of family medicine and obstetrics and gynecology at the University of Washington School of Medicine. “They can be safely used up to the first 11 weeks of pregnancy.”  

Here’s what to expect with a medication abortion: 

  • The first pill someone seeking an abortion would take is mifepristone, which blocks pregnancy hormones and is a single pill that is swallowed. 
  • The second pill, misoprostol, is taken 24 hours after the mifepristone. It’s placed under the tongue or between the gum and the cheek — not swallowed like mifepristone. Typically, four of these pills are needed to be effective. Within two to four hours, cramping and bleeding to empty the uterus can be expected. The bleeding and cramps might hurt like a bad period, but there’ll be more blood than with a regular period. 
  • If someone seeking an abortion can’t get mifepristone due to legal restrictions in their area, a misoprostol-only regimen can be used.

This method of abortion has an extremely high success rate, with its effectiveness depending on the gestational age. For example, these abortions are 98% effective at seven weeks, but closer to 95% at nine weeks. After the nine-week mark, the misoprostol dose is repeated up to 11 weeks, so the success rate stays at around 98% in ending the pregnancy.

It’s important to remember that these medical abortions can also be used for miscarriages. In all uses, bleeding can be expected to last anywhere from nine to 16 days. 

What makes medication abortions different than emergency contraception? 

The pills prescribed for abortions work differently than Plan B or other emergency contraceptive pills. 

Plan B uses the synthetic hormone levonorgestrel, which has been used in birth control for over 35 years. After unprotected sex, emergency contraceptives like Plan B work to stop the release of an egg from an ovary — also known as ovulation. It can also prevent sperm from joining with an egg — or fertilizing. Plan B is only effective up to 72 hours after unprotected sex, and the sooner it’s taken, the better. 

There are other emergency contraceptive pills on the market that work similarly to Plan B, such as Ella. This pill contains a nonhormonal drug called ulipristal acetate and can be taken up to five days after unprotected sex.  

The biggest difference between emergency contraceptives and the abortion pill is that emergency contraceptives aren’t effective on eggs that have already successfully joined with sperm. In other words, if unprotected sex has resulted in pregnancy, emergency contraceptives can’t end the pregnancy.  

Are medication abortions safe? 

Godfrey says complications from medication abortions are rare. 

“There’s less than 1% chance that a patient who uses this regimen needs any type of hospitalization, blood transfusion, antibiotics, or a surgical procedure. That’s something I really want to emphasize to patients,” says Godfrey. 

When the bleeding begins, if two maxi-pads are being filled from end to end and side to side for two hours in a row, that’s a sign of an emergency. Reach out to your doctor or an emergency room if this happens — but it rarely does. 

Because of the low risk associated with medication abortions, they don’t need to be administered by a doctor or healthcare professional in a clinic after being prescribed. Instructions are easy to follow and, because of their accessibility, count for more than 39% of all abortions. When and where you take the medication depends on your state laws, but your doctor will give you that information. 

“The two medications [mifepristone and misoprostol] are safer than many other medications that I prescribe, including penicillin, Tylenol or insulin,” says Godfrey. 

What happens after a medication abortion? 

Someone who has a medication abortion isn’t alone through the process. The prescribing doctor or healthcare professional will coach them on what to expect during and after the course of medication and after the bleeding is finished. 

While a routine in-person follow-up is not needed for most medication abortions, that option is available for those who choose to go to the clinic to assess the success of the medication abortion. A transvaginal ultrasound will typically be used for these appointments.  

For most people, telemedicine or self-assessments are enough to determine the success of medication abortions. There might be a check-in with a doctor or healthcare professional about a week after the regimen, and an at-home urine pregnancy test can be taken after four weeks to confirm the success of the abortion. 

Abortions are a necessary part of healthcare, just like any other routine preventive procedure. And with something so safe, successful and accessible as abortion pills, understanding how the medications work can help us understand why they are needed.

Barbara Clements contributed to this article. A version of this story originally appeared on the UW Medicine Newsroom.