Precautions and Warnings With Mifepristone

Specific Mifepristone Precautions and Warnings

Some warnings and precautions to be aware of prior to taking this drug include the following:
  • Vaginal bleeding and cramping are expected with mifepristone treatment when used to end a pregnancy. Most women bleed for 9 to 16 days after taking the medication, although you may bleed longer. Persistent, heavy bleeding can be a sign of a potentially serious problem. Seek immediate medical attention if you experience heavy bleeding; for example, bleeding that soaks through two thick sanitary pads per hour for two consecutive hours. Some women may require a surgical procedure to stop the bleeding.
  • There have been reports of serious infections occurring in women who received this medicine. Although rare, some infections could lead to death. It is not clear whether mifepristone actually caused the infections. However, it is important to seek immediate medical care if you have any signs of an infection, such as:
    • A high fever (100.4°F or higher for more than four hours)
    • Severe abdominal (stomach) pain
    • Tenderness in the pelvic area
    • Weakness
    • Nausea
    • Vomiting
    • Diarrhea that lasts longer than 24 hours after taking mifepristone.
  • Mifepristone decreases the effects of cortisol, a hormone made by the adrenal glands. This can lead to a problem known as adrenal insufficiency. Let your healthcare provider know right away if you experience adrenal insufficiency symptoms, including:
    • Muscle weakness
    • Nausea
    • Fatigue
    • Low blood pressure (hypotension), which could cause dizziness
    • Low blood sugar (hypoglycemia), which could cause sweating, nausea, and anxiety.
  • Mifepristone can decrease the level of potassium in your blood (this is known medically as hypokalemia). Your healthcare provider will check your potassium levels with a simple blood test before you start the medication (unless you are taking the medicine to end a pregnancy) and throughout treatment.
  • Your healthcare provider may recommend treatment with potassium supplements if you develop hypokalemia. Let your healthcare provider know if you have muscle weakness or cramps or an abnormal or irregular heartbeat. These could be signs of low potassium.
  • Women who take this medicine for the treatment of high blood sugar associated with Cushing's syndrome may develop an overgrowth or thickening of the lining of the uterus and vaginal bleeding. Let your healthcare provider know if you have any unusual or unexplained vaginal bleeding during treatment.
  • Mifepristone can cause a potentially life-threatening problem with the heart rhythm, known as QT prolongation, especially at higher doses. Therefore, if you are using this medicine for high blood sugar levels, your healthcare provider will give you the lowest dose that controls your symptoms. Taking mifepristone with other QT-prolonging medicines may increase the risk for this problem (see Drug Interactions With Mifepristone).
  • Medications known as corticosteroids may not work as well in people taking mifepristone. As a result, people who take corticosteroids for other medical conditions may have worsening symptoms of the other medical condition when mifepristone and corticosteroids are taken together. People who need corticosteroids for life-threatening conditions should not take mifepristone.
  • People who take this medication may be at risk for a fungal infection of the lungs known as Pneumocystis jiroveci pneumonia. Contact your healthcare provider if you develop signs of a lung infection, such as a cough, shortness of breath, and fever.
  • This medicine should be used with caution in people with heart disease, as it may make heart disease worse. 
  • If you are receiving mifepristone to end a pregnancy, you will need to visit your healthcare provider two days after taking mifepristone, and again about 12 days later (two weeks after your mifepristone dose). These visits are very important to make sure the medication worked and to check for potential side effects.

If your healthcare provider determines you are still pregnant two weeks after taking mifepristone, he or she will discuss other options with you, including the possibility of a surgical procedure to end your pregnancy. There is a risk for birth defects if pregnancy continues after taking mifepristone.

  • You will be given a medication guide that describes mifepristone. Make sure to take this guide with you if you need to seek emergency medical care after taking mifepristone, so your healthcare provider will know you have taken a medication to end a pregnancy.
  • You should know that you can become pregnant before you have another normal menstrual period. You can begin birth control as soon as your healthcare provider determines your pregnancy has ended.
  • Mifepristone is a pregnancy Category X medication because it can harm an unborn child (see Mifeprex and Pregnancy and Korlym and Pregnancy). It should only be used during pregnancy to terminate the pregnancy.
Last reviewed by: Kristi Monson, PharmD
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