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How Does the Abortion Pill Work?

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Since 2019, RU-486, also known as the abortion pill, has risen in popularity and has become the abortion method of choice.  

The Abortion Pill can be given up to 10 weeks of pregnancy, which can be measured based on the day of your last menstrual period.  

A pregnancy test and ultrasound should be performed prior to taking the abortion pill to make sure there is a pregnancy, and that the pregnancy is located in the uterus. Other areas where a pregnancy can be located include the fallopian tubes. When this happens, it is considered an ectopic pregnancy and is not viable.  

RU-486: What to Expect 

When a woman decides to have a medical abortion, she will receive the RU-486 pills from the abortion provider and will be instructed to take the first pill while she is at the abortion center.  

The first pill she will be given is Mifepristone. This medication is a progesterone antagonist, meaning that it works against progesterone. Progesterone is also known as the “pregnancy hormone” and it provides nutrients to the baby in the womb. This first pill stops the production of progesterone, which causes nourishment to the baby to cease. 

After the first dose is taken, she will be given the next pill from the provider and instructed to take it in the next 24- 48 hours. This next medication is Misoprostol, and it causes cramping, contractions, bleeding and expelling of the baby from the uterus.  

The expelling of the baby normally takes from 2 – 24 hours to be completed, but for some women it has been over 24 hours before the abortion is completed. 

Side Effects from the abortion pill may include nausea, vomiting, weakness, fever, chills, diarrhea, dizziness, and headache that could last 1 –2 days.  Severe side effects can include hemorrhage to the point where a blood transfusion is necessary. In severe cases, retained tissue (leftover from the pregnancy) can require a dilation and curettage procedure. This procedure requires anesthesia and involves the cervix being dilated and a metal instrument being used to scrape out the inside of the uterus. Infection can occur if tissue is left inside the uterus. 

A woman should not take the abortion pill if: 

  • She is over 10 weeks pregnant 
  • She has an IUD in place 
  • She has an Ectopic pregnancy (can be confirmed with an ultrasound performed by a licensed medical professional) 
  • She is taking blood thinners, steroids or allergic to abortion pill medications 

An ultrasound must be done before a provider gives the RU-486 pill to a patient to ensure that a woman is not over 10 weeks pregnant and that she is not experiencing an ectopic pregnancy. Taking the abortion pill when a woman has an ectopic pregnancy or is over 10 weeks pregnant can cause severe hemorrhaging and other severe side effects.  

It is very important that the abortion provider does lab work to check a woman’s blood type prior to the abortion. Women who have an RH negative blood type (A neg, B neg, O neg, AB neg) need to receive a Rhogam Injection within 72 hours after the abortion. This injection prevents antibodies from developing in the woman’s body. These antibodies can be harmful to a future pregnancy, possibly causing a miscarriage or severe health issues with the baby. 

Every woman should have a follow up with your abortion provider 2 weeks after the abortion to make sure the abortion was complete and there is nothing remaining in her uterus.  

Signs of an incomplete or failed abortion include soaking a pad every hour for 2 hours or passing lemon size or larger clots. If excessive bleeding is occurring, the patient needs to go to the ER immediately. 


  • American College of Obstetricians and Gynecologists (ACOG) Committee on Practice Bulletins — Gynecology and the Society of Family Planning. ACOG Practice Bulletin No. 143: Medical management of first-trimester abortion. Obstetrics and Gynecology. 014; doi:10.1097/01.AOG.0000444454.67279.7d. Reaffirmed 2016. 
  • Bartz DA, et al. First-trimester pregnancy termination: Medication abortion. https://www.uptodate.com/contents/search. Accessed May 6, 2020. 
  • Hatcher RA, et al., eds. Abortion. In: Contraceptive Technology. 21st ed. Ayer Company Publishers; 2018. 
  • Hoffman BL, et al. First-trimester abortion. In: Williams Gynecology. 4th ed. New York, N.Y.: McGraw-Hill Education; 2020. http://accessmedicine.mhmedical.com. Accessed May 7, 2020. 
  • Steinauer J. Overview of pregnancy termination. https://www.uptodate.com/contents/search. Accessed May 7, 2020. 
  • Dragoman M, et al. Misoprostol as a single agent for medical termination of pregnancy. https://www.uptodate.com/contents/search. Accessed May 7, 2020. 

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