Mirena Warnings and Precautions

Specific Precautions and Warnings for Mirena

Some of the warnings and precautions to be aware of prior to using Mirena include the following:
  • Although pregnancy is quite rare in women using Mirena, about half of all pregnancies that do occur while taking Mirena are ectopic (located outside the uterus). These pregnancies cannot survive, often require surgery, and can result in permanent damage that can lead to infertility. Be watchful for any signs of an ectopic pregnancy, such as severe abdominal pain (stomach pain) accompanied by unusual vaginal bleeding. You should not use Mirena if you have ever had an ectopic pregnancy or if your healthcare provider feels that you are at risk for an ectopic pregnancy.
  • For pregnancies that are not ectopic (otherwise normal pregnancies within the uterus), problems can occur. Leaving Mirena in place increases the risk of miscarriages, premature birth, and severe infection, and the fetus will continuously be exposed to the hormone in Mirena. Removal of Mirena is recommended, but this can also result in a miscarriage (see Mirena and Pregnancy for more information).
  • Very rarely, the insertion of Mirena can cause a very serious infection. Let your healthcare provider know immediately if you develop severe pain within hours after the insertion of Mirena, as immediate treatment is essential.
  • Intrauterine contraceptives (IUCs), such as Mirena, may increase the risk of pelvic inflammatory disease (PID), a condition that can increase the risk of ectopic pregnancies and infertility. You should not use Mirena if you have ever had PID, unless you have had an intrauterine (non-ectopic) pregnancy since you had PID.
  • It is common and normal for Mirena to cause irregular periods and bleeding or spotting for the first three to six months. After that, many women experience lighter and less frequent periods. Some women will stop having periods altogether. The first time your period is late, let your healthcare provider know, as he or she may want to make sure you are not pregnant.
  • It is possible for Mirena to become embedded in the uterus. This can make it less effective and more difficult to remove.
  • It is possible for Mirena to perforate the uterus. Usually, this happens during insertion. It can be severe enough to require surgery and can cause serious problems. In order to help prevent this, after a birth or a second trimester abortion or miscarriage, it is recommended to postpone insertion of Mirena until the uterus can return to its normal pre-pregnancy size (this is not necessary after a first trimester abortion or miscarriage), usually after at least six weeks.
  • Ovarian cysts are common in women using Mirena. Usually, these cysts are painless and do not cause any problems (and do not require any treatment).
  • Women who have certain heart conditions (especially heart valve problems) are at risk for heart infections. These women usually need antibiotics for many procedures (such as dental procedures) to avoid an infection that could spread to the heart. Antibiotics are recommended for the insertion or removal of Mirena in such women.
  • Women with a weakened immune system (often cause by diabetes or by chronic use of steroid medications) should be monitored carefully for signs of infection after insertion or removal of Mirena.
  • If you have a blood clotting disorder or if you take "blood-thinning" medications, your healthcare provider may need to monitor you more closely while you are using Mirena.
  • The insertion of Mirena should be postponed if you have a vaginal or cervical infection.
  • The hormone in Mirena may affect blood sugar levels. This is especially important for women with diabetes.
  • It is not known if Mirena interacts with any other medications (see Mirena Drug Interactions for more information).
  • Levonorgestrel (the hormone in Mirena) passes through breast milk. Therefore, if you are breastfeeding or plan to start breastfeeding, discuss this with your healthcare provider prior to taking the drug (see Mirena and Breastfeeding).
Last reviewed by: Kristi Monson, PharmD
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