Mirena is a long-acting, reversible birth control implant called a hormonal intrauterine device (IUD) manufactured by Bayer Pharmaceuticals. An IUD is a small, flexible, T-shaped device that doctors implant in the uterus. Mirena uses levonorgestrel — a progestin birth control hormone — to prevent pregnancy. It releases a small amount of hormones into the uterus over time.

*Please seek the advice of a medical professional before discontinuing the use of this medical device.

Mirena IUD

An estimated 2 million American women have a Mirena, a T-shaped intrauterine device (IUD) that contains the hormone levonorgestrel, a type of progestin, which is released over time.

The device can remain in the body providing birth control for up to five years. Like other IUDs, Mirena claims to be over 99 percent effective at preventing pregnancy. Levonorgestrel is also taken orally in emergency contraception to prevent pregnancy after unprotected sexual intercourse.

The first levonorgestrel IUD, Mirena, was first introduced by Schering AG in Finland in 1993 and later made available in dozens of other countries. The FDA approved it for the U.S. market in December 2000. Schering was purchased by Bayer in 2006. The device is now available in more than 100 countries.

Mirena IUD up-close
Mirena IUD up-close

Bayer also markets two other intrauterine devices that it says are part of the Mirena family – Kyleena and Skyla. According to the company’s 2016 annual report, the product line was one of its top sellers, bringing in almost $1.2 billion worldwide, including nearly $800 million in the United States. That compares to about $1.1 billion worldwide with about $727 million in the U.S. in 2015. The company says its patent on the method of insertion for Mirena doesn’t expire until 2029.

Mirena is considered as effective as sterilization in preventing pregnancy.

A Canadian researcher described Mirena as the “gold standard” among levonorgestrel-releasing IUDs. It has been the subject of more than 2,000 published studies that examined its uses in gynecology and family planning.

News reports said sales of IUDs and other long-term forms of birth control received a boost in the U.S. after the November 2016 elections, as women worried their healthcare coverage would diminish rushed to get contraception that would outlast the presidency.

How Does Mirena Work?

IUDs with levonorgestrel work mainly by making it difficult for sperm to fertilize an egg. Mirena slowly releases 20 mcg of the synthetic hormone into the uterus each day. Birth control pills, in comparison, typically release 150 mcg into the body daily.


Mirena prevents pregnancy in three ways: it slowly releases levonorgestrel which inhibits sperm’s ability to move, causes mucus in the cervix to thicken and thins the lining of the uterus.

Levonorgestrel has a long history of use in many approved hormonal products in the US. These uses include both contraception and menopausal therapy.

In some women, the hormonal secretion of the IUD is enough to prevent ovulation.

As a result, the fluid in the uterus changes to contain a high amount of white blood cells and other cellular changes that inhibit sperm’s ability to move in the uterus.

Another effect is that Mirena thickens the mucus in the cervix, blocking sperm from passing into the uterus or fallopian tubes where fertilization can happen. The thickened mucus may carry additional benefits, such as fewer upper genital tract infections and less pelvic inflammatory disease.

And finally, the Mirena changes the lining of the uterus, thinning it within three months of insertion. In addition to contraception, this can also have the effect of reducing or stopping menstrual bleeding while the Mirena is in place.

Mirena and other IUDs do not protect against sexually transmitted diseases.

Urogynecologist Dr. Christopher Walker explains what Mirena is and how it works

Who Should Get a Mirena?

Mirena, which is recommended for women who have already had at least one child, was also approved by the FDA in 2009 to treat heavy periods in women who chose IUDs as their method of contraception. Some experts say that the device need not be limited to women who have given birth, as this restriction is not based on evidence.

Mirena is also usually recommended as contraception for patients with certain medical conditions, such as a history of deep venous thrombosis, type 1 diabetes, liver disease, epileptic seizures, and conditions involving a compromised immune system, such as HIV.

The flexible, plastic device is inserted vaginally by a trained healthcare provider during an office visit. It is made from medical grade polyethylene and has a cylindrical steroid reservoir made of silicone and 51 mg of levonorgestrel covering the vertical part of the T. It releases 20 mcg of levonorgestrel a day for five years.

The device costs about $800 and is covered under the contraception provision of the Affordable Care Act, meaning it should be provided at no charge to most women with insurance as long as the contraception mandate remains in place and the woman’s employer isn’t covered by one of the court-sanctioned religious exceptions.

Women Who Shouldn’t Use Mirena

Mirena is not recommended for women who:

  • Have or get pelvic infections
  • Are or may be pregnant
  • Have or have had known or suspected breast cancer or other progestin-sensitive cancer
  • Have uterine anomaly, including fibroids, if they distort the uterine cavity
  • Have lower, uncontrolled genital tract infections
  • Have unexplained uterine bleeding
  • Have or have had a history of acute pelvic inflammatory disease

Caution is recommended for women who:

  • Are taking anticoagulants or have coagulopathy
  • Have migraine, focal migraine with asymmetrical vision loss or other symptoms of transient cerebral ischemia
  • Experience exceptionally severe headaches
  • Have anomalies or cancers of the reproductive system
  • Have a marked increase of blood pressure or severe arterial disease, such as a stroke or heart attack
  • Have liver disease

Insertion of Mirena

Mirena can be inserted by a doctor during a regular office visit. The procedure can be painful, with some women feeling pain similar to mild cramps, and others experiencing more severe pain. Many women, however, experience little or no pain. The procedure typically takes about five minutes and involves a speculum, an instrument to manipulate the uterus and another instrument to measure it so the Mirena is placed properly in the uterus.

The two horizontal arms of the T are folded upward during insertion so the device is shaped like a matchstick. At the conclusion of the insertion, the arms extend to the side. When in place, the Mirena is 32 mm tall and 32 mm across the top of the T.

The device has two threads attached to it, which are used to make sure Mirena is in place and to assist in its removal. Women are instructed to check their threads monthly. If the threads are not in place or have significantly shortened, they may have broken or retracted into the cervical canal or uterus.

Infection & Perforation RiskIt’s important that a doctor uses sterile procedures for inserting Mirena to lower the chance that the patient will develop infections. When Mirena perforates the uterus, it most commonly happens during insertion. If this happens, the device must be removed, sometimes surgically.

Makers of Mirena recommend that patients see a doctor four to six weeks after having a Mirena inserted. The device becomes effective seven days after insertion.

Although use of IUDs was once thought to increase the risk of pelvic inflammatory disease, Mirena may actually help protect against infection, especially in women who have not previously given birth.

Side Effects and Complications

Some women report extreme pain during insertion and for several days after, while others experience relatively minor discomfort or cramping. The most common side effect of Mirena is changes in menstrual bleeding.

If pregnancy occurs in a patient who has Mirena, there is a danger of spontaneous abortion, preterm labor and ectopic pregnancy, which can be fatal.

Mirena IUD xray
X-ray showing Mirena placement in the uterus

Another risk associated with Mirena is that the device could perforate the wall of the uterus and travel to other parts of the body, potentially damaging other organs and tissue. Sometimes the Mirena spontaneously comes out of the body through the vagina. This happens most often in the first three months after placement and is rare later than that.

The Mirena can also have an effect on mood and some women experience dizziness. If the woman becomes pregnant, she must have her doctor remove the Mirena because of the danger of spontaneous abortion and preterm labor. However, removing it or manipulating it may result in the loss of the pregnancy.

The device can be removed at any time a patient would like to become pregnant. Bayer says 8 out of 10 women who have Mirena removed succeed in becoming pregnant within a year.

Some women report developing a condition called intracranial hypertension or pseudotumor cerebri, which is an unexplained increase of pressure inside the head, which can seem like the symptoms of a brain tumor and can lead to vision loss.


Elaine Silvestrini is a career journalist with a strong desire to learn, explain, and help people. At Drugwatch, Elaine has reported about trials over whether talcum powder caused ovarian cancer and allegations that Androgel causes heart problems in patients who use it. She has chronicled the billions of dollars generated for big pharmaceutical companies by certain drugs and efforts to warn consumers about the dangers of specific medical problems. Elaine has received six health literacy certificates for completing courses offered by the Centers for Disease Control and Prevention. She brings more than 20 years of experience covering state and federal court systems, learning the intricacies of criminal and civil law, developing investigative pieces about how the law affects people’s lives and digging through and digesting reams of court records on a daily basis.

Hide Sources

  1. Couzin-Frankel, J. (2011, July 15) Contraceptive Comeback: The Maligned IUD Gets A Second Chance. Retrieved https://www.wired.com/2011/07/ff_iud/
  2. Cougherty, C. (2006, June 15). Bayer to Acquire Schering; Germen Merck to Sell Stake. Retrieved http://www.nytimes.com/2006/06/15/business/worldbusiness/15drug.html
  3. Mayo Clinic. (n.d.) Pseudotumor celebri. Retrieved http://www.mayoclinic.org/diseases-conditions/pseudotumor-cerebri/home/ovc-20249919
  4. Mirena. (n.d.). Mirena. Retrieved https://www.mirena-us.com/about-mirena/
  5. Cohen, E. (2017, January 25). Women rush to get IUDs because of Trump. Retrieved http://www.cnn.com/2017/01/25/health/iuds-trump/index.html
  6. Mirena. (n.d.). Mirena Videos. Animated Insertion Video. Retrieved https://hcp.mirena-us.com/placement-and-removal/insertion-and-removal-video.php
  7. Association of Reproductive Health Professionals. (n.d.). The Facts About Intrauterine Contraception. Retrieved http://www.arhp.org/Publications-and-Resources/Clinical-Fact-Sheets/The-Facts-About-Intrauterine-Contraception-
  8. Planned Parentood. (n.d.). IUD. Retrieved https://www.plannedparenthood.org/learn/birth-control/iud
  9. Erian, M., McLaren, G., and Baartz, D. (2011, January-March). The Wantering Mirena: Laparoscopic Retrieval. Retrieved https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3134688/
  10. Costescu, D.J. (2016, October 13). Levonorgestrel-releasing intrauterine systems for long-acting contraception: current perspectives, safety, and patient counseling. Retrieved: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5066847/
  11. Bayer. (2017) Annual Report 2016. Retrieved http://www.annualreport2016.bayer.com/servicepages/search.php?q=mirena&pageID=29873
  12. International Contraception Access. (n.d.). Levonorgestrel Intrauterine System. (LNG IUS) Provider Information Sheet. Retrieved http://www.ica-foundation.org/LNG_IUS_provider_info.pdf