Drugs Used to Terminate Pregnancy

Medical abortion employs prescription medications to terminate an early pregnancy. According to the American College of Obstetricians and Gynecologists, medical abortion is approximately 95 percent effective in terminating early pregnancy. Some women consider this process a more natural abortion option as it avoids a surgical procedure and use of local or general anesthesia. The ability to go through the pregnancy termination process privately also appeals to some women. Mifepristone and misoprostol, which are used in combination, are approved by the US Food and Drug Administration for medical abortions.

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Mifepristone and Misoprostol

The combination of mifepristone (Mifeprex) and misoprostol is FDA approved to medically induce an abortion up to 70 days after the first day of a woman's last menstrual period, or roughly 8 weeks into a pregnancy.


Mifepristone is given on the first day of the medical abortion process. It acts as an antiprogestational agent, meaning it blocks the effects of the hormone progesterone. Progesterone plays an essential role in early pregnancy as it stimulates and maintains the uterine lining changes necessary to support the developing embryo. Mifepristone blocks these effects thereby terminating the pregnancy. According to the 2016 FDA-approved protocol, a single 200 mg dose of mifepristone is taken by mouth.


Misoprostol is a man-made drug that mimics the functions of a naturally occurring substance called prostaglandin E1. Misoprostol triggers uterine contractions, which completes the medical abortion by stimulating expulsion of the tissues from the terminated pregnancy as well as the uterine lining. A single dose of 800 micrograms of misoprostol is taken 24 to 48 hours after taking mifepristone. The misoprostol is administered as four 200 microgram pills inserted between the cheek and gum -- 2 on each side of the mouth -- for 30 minutes. Any remaining pill remnants are washed down with water after this period.

Side Effects

Menstrual-like cramps and bleeding, often heavier than a typical period, are normal and expected with a medical abortion. Common side effects from the combination of mifepristone and misoprostol include:

  • Nausea, with or without vomiting
  • Diarrhea
  • Weakness
  • Headache
  • Dizziness
  • Fever and/or chills

Serious side effects are rare, occuring in less than 0.5 percent of women according to the manufacturer's prescribing information for mifepristone. Possible serious side effects include heavy bleeding requiring a blood transfusion and a uterine infection, with or without spread to the bloodstream.


An induced abortion using a combination of mifepristone and misoprostol is not appropriate for all women seeking to terminate an early pregnancy. The FDA-approved protocol for use of these drugs is not recommended for women whose pregnancy is further along than 10 weeks when counting from first day of the last menstrual period. The mifepristone and misoprostol regimen is also not recommended for women with an intrauterine device, or IUD, in place -- although the drugs can be used if the IUD is removed beforehand. Other contraindications include:

  • Confirmed or suspected ectopic pregnancy, meaning a pregnancy outside the uterus
  • Long-term adrenal gland failure
  • Long-term use of a corticosteroid medication, such as prednisone or methylprednisolone
  • Bleeding disorder or use of a prescription blood thinner
  • Porphyria, a rare inherited disorder
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