Search Knowledgebase

Topic Contents



Generic Name

How It Works


  • Softens and opens (dilates) the cervix.
  • Causes uterine contractions.
  • Starts (induces) labour.

Why It Is Used

Misoprostol is a prostaglandin medicine used to terminate a pregnancy by starting labour. It is more effective when used in combination with methotrexate than when used alone. This is an unlabelled use of misoprostol.

Misoprostol is also used to prevent stomach ulcers (labelled use) and for induction of labour for childbirth (unlabeled use).

Misoprostol may also be used to:

  • Complete a spontaneous missed abortion (incomplete miscarriage).
  • Start labour in second-trimester abortions.
  • Start labour in third-trimester abortions. Third-trimester abortions are not done unless the fetus has died or has severe medical problems and will not survive.
  • Dilate the cervix 3 to 4 hours before a surgical abortion procedure.
  • Soften the cervix for induction of labour.
  • Soften the cervix for special gynecologic tests.

How Well It Works

Misoprostol used alone may terminate a pregnancy. But it is more often used with other medicines, such as methotrexate, in first-trimester abortions.

Misoprostol alone, moistened and used vaginally, is over 90% effective in terminating first-trimester pregnancies of less than 8 weeks.1

Misoprostol can be given orally, buccally (dissolved between the gums and cheek), or vaginally. Misoprostol is slightly more effective when taken vaginally than when taken by mouth.1 But many doctors are only giving misoprostol by mouth because of reports of a rare, fatal infection that affected a few women after using vaginal misoprostol. Some studies have shown that taking misoprostol buccally works as well as when it is given vaginally or orally.2, 3

Side Effects

This method of abortion causes symptoms similar to a miscarriage (such as severe cramping and vaginal bleeding) as tissue and clots pass from the uterus. Symptoms may include:

  • Nausea.
  • Vomiting.
  • Diarrhea.
  • Headache.
  • Dizziness.
  • Chills or hot flushes (sweating and feeling overly hot).
  • Shivering.
  • Fatigue.

In rare cases, a severe infection (sepsis) may occur after having an abortion. Signs of serious infection include weakness, nausea, and diarrhea with or without belly pain. This rare infection may not cause a fever. Call your doctor or go to the hospital if you have any of these signs of a serious infection after having a medical abortion.

Signs of complications

Call your doctor immediately if you have any of these symptoms after an abortion:

  • Severe bleeding. Both medical and surgical abortions usually cause bleeding that is different from a normal menstrual period. Severe bleeding can mean:
    • Passing clots that are bigger than a golf ball, lasting 2 or more hours.
    • Soaking more than 2 large pads in an hour, for 2 hours in a row.
    • Bleeding heavily for 12 hours in a row.
  • Signs of infection in your whole body, such as headache, muscle aches, dizziness, or a general feeling of illness. Severe infection is possible without fever.
  • Severe pain in the abdomen that is not relieved by pain medicine, rest, or heat
  • Hot flushes or a fever of 38°C (100.4°F) or higher that lasts longer than 4 hours
  • Vomiting lasting more than 4 to 6 hours
  • Sudden abdominal swelling or rapid heart rate
  • Vaginal discharge that has increased in amount or smells bad
  • Pain, swelling, or redness in the genital area

Call your doctor for an appointment if you have had any of these symptoms after a recent abortion:

  • Bleeding (not spotting) for longer than 2 weeks
  • New, unexplained symptoms that may be caused by medicines used in your treatment
  • No menstrual period within 6 weeks after the procedure
  • Signs and symptoms of depression. Hormonal changes after a pregnancy can cause depression that requires treatment.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Choosing a medical or surgical procedure for an abortion will depend on your past health, how many weeks pregnant you are, what options are available where you live, and your personal preferences.

Misoprostol is not used in women who have an allergy to misoprostol or other prostaglandins.

Misoprostol can cause fetal abnormalities, so a follow-up surgical abortion will be done to prevent a fetus from developing abnormally.

Use of misoprostol for medical abortion is an unlabelled use. Misoprostol is approved (labelled) for preventing and treating stomach ulcers in people taking non-steroidal anti-inflammatory drugs (NSAIDs) on a long-term schedule.

Misoprostol does not have any known drug interactions.

Unlike other prostaglandins, misoprostol does not increase the risk of a heart attack or bronchospasm.

Complete the new medication information form (PDF) (What is a PDF document?) to help you understand this medication.



  1. American College of Obstetricians and Gynecologists (2005, reaffirmed 2009). Medical management of abortion. ACOG Practice Bulletin No. 67. Obstetrics and Gynecology, 106(4): 871–882.
  2. Middleton T, et al. (2005). Randomized trial of mifepristone and buccal or vaginal misoprostol for abortion through 56 days of last menstrual period. Contraception, 72(5): 328–332.
  3. Winikoff B, et al. (2008). Two distinct oral routes of misoprostol in mifepristone medical abortion: A randomized controlled trial. Obstetrics and Gynecology, 112(6): 1303–1310.


By Healthwise Staff
Primary Medical Reviewer Sarah Marshall, MD - Family Medicine
Primary Medical Reviewer Anne C. Poinier, MD - Internal Medicine
Specialist Medical Reviewer Rebecca H. Allen, MD, MPH - Obstetrics and Gynecology
Specialist Medical Reviewer Femi Olatunbosun, MB, FRCSC - Obstetrics and Gynecology
Last Revised January 4, 2011

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information.