Mirena FAQs

The Mirena IUS is essentially an intrauterine device, or IUD. Its manufacturer calls it an “intrauterine system” because it stops sperm from fertilizing an egg like an IUD, and it stops a fertilized egg from implanting in the uterus. Otherwise, the device is the same T-shape and size of a standard IUD. That is why we use IUS and IUD interchangeably when referring to it.

Bayer HealthCare Pharmaceuticals, Inc., of Montville, New Jersey, manufactures the Mirena IUS / IUD. Bayer HealthCare Pharmaceuticals is the U.S.-based pharmaceuticals operation of Bayer HealthCare LLC, a division of Bayer AG, a German pharmaceutical and chemical firm that is best known for its aspirin.

The Mirena IUS / IUD is inserted into a woman’s uterus by a doctor to provide long-term birth control. Once in place, it slowly releases a synthetic version of the hormone progestin called “levonorgestrel.” This synthetic hormone thickens the cervical mucus, which blocks sperm from reaching an egg. The hormone also thins the lining of the uterus, which reduces the ability of a fertilized egg to implant itself and grow.

No, there are several reasons a Mirena IUS may not be suitable.

The Mayo Clinic says your health care provider may discourage use of Mirena if you:

• Had or have breast cancer
• Have uterine or cervical cancer
• Have liver disease
• Have uterine abnormalities, such as fibroids, that interfere with the placement or retention of the Mirena IUD
• Have a pelvic infection or have a history of pelvic inflammatory disease (PID)
• Have unexplained vaginal bleeding
• Have inflammation of the vagina or cervix or a lower genital tract infection
• Are allergic to any component of the Mirena IUD
• Have or are at high risk of a sexually transmitted infection
• Have had previous problems with an IUD.

The U.S. Food and Drug Administration (FDA) says it has received complaints of the Mirena IUS causing pelvic inflammatory disease (PID) and other abdominal and pelvic pain, as well as headache, nausea, uterine bleeding, ovarian cysts, vaginitis, nervousness, depressed libido and depressed mood.

PID is an infection of the reproductive organs that can lead to serious consequences, including infertility, ectopic pregnancy (a pregnancy in the fallopian tube or elsewhere outside of the womb), abscess formation and chronic pelvic pain.

Yes. A more serious problem is that the Mirena IUD tends to move from where it is inserted. This enables the device to embed in the uterine wall or elsewhere in the abdominal cavity or to perforate the uterine wall, intestines or other internal organs. Perforated bowels and other organs can cause infection, including sepsis, a life-threatening blood infection.

In 2008, the FDA approved additions to safety labels on Mirena packaging to include warnings that addressed long-term effects and congenital anomalies, possibility of miscarriage after long-term use of Mirena, cautions about perforation and partial or complete expulsion of the IUD, and a warning against use by breast cancer patients.

The FDA sent warning letters to Bayer HealthCare Pharmaceuticals in March and December 2009 accusing the manufacturer of overstating the benefits of its Mirena IUS contraceptive and downplaying its serious risks. The letters asked the firm to cease using existing print and online promotional material and to revise the content of future promotional material for the Mirena IUS.