Serious. These medicines may interact and cause very harmful effects. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.
How the interaction occurs:
Mifepristone interferes with the way hormonal contraceptives work and results in the loss of a pregnancy.
What might happen:
Hormonal contraceptive products (such as "the pill", the "mini-pill", Norplant, birth control injections, and the patch) may not prevent you from becoming pregnant while you are taking mifepristone. If you become pregnant while taking mifepristone, you will have a miscarriage.
What you should do about this interaction:
Let your healthcare professionals (e.g. doctor or pharmacist) know that you are taking these medicines together. If you are a female of reproductive age and have not been surgically sterilized (tubal ligation, double ovariectomy, or hysterectomy) you should use a non-hormonal form of birth control (such as an intrauterine device [IUD] or barrier methods) while taking mifepristone and for one month after stopping mifepristone. Discuss birth control options with the doctor that prescribed mifepristone for you and with your gynecologist (OB/GYN). Be sure to undergo a pregnancy test if you stop taking mifepristone for 14 days before restarting the medication. If you think that you may be pregnant or have had a miscarriage, contact your doctor right away.Your healthcare professionals may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.Reference:1.Korlym (mifepristone) US Prescribing Information. Corcept Therapeutics February 17, 2012.