mirena2Mirena is a long acting reversible contraceptive that is implanted into the womb.  It is considered a hormonal intrauterine contraceptive device (IUD) that releases small amounts of the hormone levonorgestrel locally into uterus through a soft and flexible plastic device approximately 3 cm long.   It provides up to five years of birth control protection.

The maker of Mirena, Bayer, says that it is more than 99% effective at preventing pregnancy, making it one of the more reliable birth controls on the market.  In addition to being prescribed as birth control, it may also be prescribed for heavy periods for some women. But, Mirena is not without controversy.  There is growing concern and scientific evidence that Mirena may present serious health complications.  As with all medications and medical devices, proper use and care must be taken.

How Is It Used?

Mirena is inserted into the womb after a comprehensive medical examination that includes a breast exam, Pap smear, full pelvic examination and a blood pressure test.  The cervix is cleaned prior to insertion and it typically takes just a few moments.  It can be inserted at any time during the period.  Mirena can stay in the womb for up to five years; however it is recommended that routine checkups be conducted at regular intervals.  It can be removed at any time, and fertility returns to normal immediately.  As with insertion, removal should take place during the period.  Most women feel moderate discomfort during insertion and removal, any significant pain during either procedure should be brought to the immediate attention of the physician.

Does It Work?

Mirena is considered an effective birth control method.  Studies show that between 6 and 8 women per thousand become pregnant during the first year that Mirena is in use.  This is considered very low.  However, it is important to note that if a woman becomes pregnant while Mirena is in the body, it can present very serious complications including miscarriage and permanent infertility.  At the first sign of pregnancy while Mirena is in use, it is essential that women consult with their physician immediately.  In addition, if any of the following conditions are experienced, consult with a healthcare professional immediately:

  • Periods change and cause mild, moderate or severe discomfort
  • Period is delayed
  • Pregnancy is suspected
  • Abnormal pain, fever or unusual vaginal discharge is experienced
  • Either sexual partner feels pain or discomfort during intercourse
  • The IUD has moved

During the first 3-6 months women should have a follow up appointment with their physician to ensure that it is properly in place and check for any side effects.  During this time, the period may become irregular with spotting and light bleeding and the number of days may increase.  As the body adjusts to the addition of levonorgestrel, the number of days of bleeding is likely to decrease, however may remain irregular.  Some women find that their periods will stop altogether.  The total blood loss per menstrual cycle will continue to decrease while Mirena is in the body.

Notes & Side Effects

All contraceptives have some side effects.  Common mild side effects for Mirena include changes in periods, headaches or migraines, elevated blood pressure, dizzy spells, nosebleeds, abdominal pain, weight gain, sinus problems, and discomfort during intercourse.  Levonorgestrel is the chemical hormone that is released through Mirena.  It is not related to the progesterone that our body produces.  Adverse reactions to levonorgestrel include nausea, cramping, weight gain and migraines.  While Mirena and levonorgestrel is considered safe for women that are breastfeeding, a study from Norway indicates that infants whose mother was receiving levonorgestrel from birth control had higher rates of respiratory infections, skin conditions and eye infections as well as a higher proportion of neurological conditions.

In addition to the mild to moderate side effects above, serious complications have been known to occur with Mirena.  This includes the IUD spontaneously moving out of place and embedding in the uterine wall, or to another part of the body including the fallopian tubes.  This will require emergency surgery.  The United States Food & Drug Administration reports over 45,000 cases where women have directly reported complications while using Mirena.  This includes dislocation, and migration.  Over 6% of the complications resulted in surgery or hospitalization.  Mirena may be pushed out of place or expelled during muscular contractions including those during the menstruation cycle.

Mirena is not recommended for women that have one or more of any of the following conditions:

  • Suspected pregnancy
  • Current or recurrent pelvic inflammatory disease
  • Infection of the womb after giving birth or after abortion
  • Untreated cervicitis
  • Cancer of the cervix or womb
  • Abnormal womb bleeding
  • Abnormality of cervix or womb including fibroids
  • Disturbances in blood clotting
  • Congenital heart disease

Sources And Further Reading:

Where to report adverse reaction in US:
Call:  1-800-FDA-1088
FDA Online Reporting Form For Adverse Effects
FDA Form For Download To Report Adverse Effects
In Canada:
Canada Vigilance Program
Marketed Health Products Directorate
Health Canada
Address Locator:  0701E
Ottawa, Ontario, K1A 0K9
Telephone Hotline:  866-234-2345


Kathleen McCoy is professional beauty, education and healthcare analyst and writer. A University of Maryland graduate, Kathleen has traveled and studied extensively throughout Europe, the Middle East, Africa and North America covering skin care and natural beauty techniques from around the globe.

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