Mifeprex RU486

Last updated on RxList: 3/2/2021
Mifeprex RU486 Side Effects Center

What Is Mifeprex?

Mifeprex (mifepristone) is a synthetic steroid indicated for the medical termination of intrauterine pregnancy through 49 days of pregnancy. Mifeprex Tablets are available in generic form.

What Are Side Effects of Mifeprex?

Expected side effects of Mifeprex include:

  • bleeding and
  • cramping

Other side effects of Mifeprex include:

  • pelvic pain,
  • nausea,
  • diarrhea,
  • stomach pain,
  • dizziness,
  • tired feeling,
  • weakness,
  • back pain, and
  • allergic reactions such as closing of the throat, swelling of the lips, and tongue, or face. Seek emergency medical attention if any of these allergic reactions occur.

Dosage for Mifeprex

Mifeprex is available in 200mg strength tablets. Treatment with Mifeprex and misoprostol for the termination of pregnancy requires three office visits. Patients must understand the necessity of completing the treatment schedule including a follow-up visit approximately 14 days after taking Mifeprex.

What Drugs, Substances, or Supplements Interact with Mifeprex?

Mifeprex may interact with medications to treat hepatitis or HIV, medicines to prevent rejection of a transplanted organ, migraine headache medication, antibiotics, antifungals, heart or blood pressure medications, seizure medication, or thyroid medications. Tell your doctor all medications and supplements you use.

Mifeprex During Pregnancy and Breastfeeding

Another pregnancy can occur following termination of pregnancy and before resumption of normal menses. Breastfeeding women should consult with their health care provider to decide if they should discard their breast milk for a few days following administration of the medications.

Additional Information

Our Mifeprex (mifepristone) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Mifeprex RU486 Consumer Information

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Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

  • a fever higher than 100.4 degrees F (38 degrees C) lasting longer than 4 hours;
  • a general ill feeling or fast heartbeats;
  • severe pelvic pain or tenderness;
  • severe or ongoing nausea, vomiting, diarrhea, weakness; or
  • no vaginal bleeding at all after taking Mifeprex.

Common side effects may include:

  • heavy vaginal bleeding for 2 days;
  • light vaginal bleeding or spotting for up to 16 days;
  • fever, chills, weakness;
  • dizziness; or
  • nausea, vomiting, diarrhea.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Mifeprex RU486 (Mifepristone (RU486))

Mifeprex RU486 Professional Information


The following adverse reactions are described in greater detail in other sections:

Clinical Trials Experience

Because clinical studies are conducted under widely varying conditions, adverse reaction rates observed in the clinical studies of a drug cannot be directly compared to rates in the clinical studies of another drug and may not reflect the rates observed in practice.

Information presented on common adverse reactions relies solely on data from U.S. studies, because rates reported in non-U.S. studies were markedly lower and are not likely generalizable to the U.S. population. In three U.S. clinical studies totaling 1,248 women through 70 days gestation who used mifepristone 200 mg orally followed 24-48 hours later by misoprostol 800 mcg buccally, women reported adverse reactions in diaries and in interviews at the follow-up visit. These studies enrolled generally healthy women of reproductive age without contraindications to mifepristone or misoprostol use according to the MIFEPREX product label.

Gestational age was assessed prior to study enrollment using the date of the woman's last menstrual period, clinical evaluation, and/or ultrasound examination.

About 85% of patients report at least one adverse reaction following administration of MIFEPREX and misoprostol, and many can be expected to report more than one such reaction. The most commonly reported adverse reactions (>15%) were nausea, weakness, fever/chills, vomiting, headache, diarrhea, and dizziness (see Table 1). The frequency of adverse reactions varies between studies and may be dependent on many factors, including the patient population and gestational age.

Abdominal pain/cramping is expected in all medical abortion patients and its incidence is not reported in clinical studies. Treatment with MIFEPREX and misoprostol is designed to induce uterine bleeding and cramping to cause termination of an intrauterine pregnancy. Uterine bleeding and cramping are expected consequences of the action of MIFEPREX and misoprostol as used in the treatment procedure. Most women can expect bleeding more heavily than they do during a heavy menstrual period [see WARNINGS AND PRECAUTIONS].

Table 1 lists the adverse reactions reported in U.S. clinical studies with incidence >15% of women.

Table 1: Adverse Reactions Reported in Women Following Administration of Mifepristone (oral) and Misoprostol (buccal) in U.S. Clinical Studies

Adverse Reaction # U.S. studies Number of Evaluable Women Range of frequency (%) Upper Gestational Age of Studies Reporting Outcome
Nausea 3 1,248 51-75% 70 days
Weakness 2 630 55-58% 63 days
Fever/chills 1 414 48% 63 days
Vomiting 3 1,248 37-48% 70 days
Headache 2 630 41-44% 63 days
Diarrhea 3 1,248 18-43% 70 days
Dizziness 2 630 39-41% 63 days

One study provided gestational-age stratified adverse reaction rates for women who were 57-63 and 64-70 days; there was little difference in frequency of the reported common adverse reactions by gestational age.

Information on serious adverse reactions was reported in six U.S. and four non-U.S. clinical studies, totaling 30,966 women through 70 days gestation who used mifepristone 200 mg orally followed 24-48 hours later by misoprostol 800 mcg buccally. Serious adverse reaction rates were similar between U.S. and non-U.S. studies, so rates from both U.S. and non-U.S. studies are presented. In the U.S. studies, one studied women through 56 days gestation, four through 63 days gestation, and one through 70 days gestation, while in the non-U.S. studies, two studied women through 63 days gestation, and two through 70 days gestation. Serious adverse reactions were reported in <0.5% of women. Information from the U.S. and non-U.S. studies is presented in Table 2.

Table 2: Serious Adverse Reactions Reported in Women Following Administration of Mifepristone (oral) and Misoprostol (buccal) in U.S. and Non-U.S. Clinical Studies

Adverse Reaction U.S. Non-U.S.
# of studies Number of Evaluable Women Range of frequency (%) # of studies Number of Evaluable Women Range of frequency (%)
Transfusion 4 17,774 0.03-0.5% 3 12,134 0-0.1%
Sepsis 1 629 0.2% 1 11,155 <0.01%*
ER visit 2 1,043 2.9-4.6% 1 95 0
Hospitalization Related to Medical Abortion 3 14,339 0.04-0.6% 3 1,286 0-0.7%
Infection without sepsis 1 216 0 1 11,155 0.2%
Hemorrhage NR NR NR 1 11,155 0.1%
NR= Not reported
* This outcome represents a single patient who experienced death related to sepsis.

Postmarketing Experience

The following adverse reactions have been identified during postapproval use of MIFEPREX and misoprostol. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Infections and infestations: post-abortal infection (including endometritis, endomyometritis, parametritis, pelvic infection, pelvic inflammatory disease, salpingitis)

Blood and the lymphatic system disorders: anemia

Immune system disorders: allergic reaction (including anaphylaxis, angioedema, hives, rash, itching)

Psychiatric disorders: anxiety

Cardiac disorders: tachycardia (including racing pulse, heart palpitations, heart pounding)

Vascular disorders: syncope, fainting, loss of consciousness, hypotension (including orthostatic), light-headedness

Respiratory, thoracic and mediastinal disorders: shortness of breath

Gastrointestinal disorders: dyspepsia

Musculoskeletal, connective tissue and bone disorders: back pain, leg pain

Reproductive system and breast disorders: uterine rupture, ruptured ectopic pregnancy, hematometra, leukorrhea

General disorders and administration site conditions: pain

Read the entire FDA prescribing information for Mifeprex RU486 (Mifepristone (RU486))

© Mifeprex RU486 Patient Information is supplied by Cerner Multum, Inc. and Mifeprex RU486 Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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