Mirena is a type of birth control called an intrauterine device (IUD) and with typical use has a failure rate of 0.2 percent according to the CDC. Mirena, also called the hormonal IUD, is a plastic, T-shaped frame that is inserted into the uterus.
Side effects of Mirena include abnormal vaginal bleeding that you may notice as an unpredictable, light or absent menstrual flow. Discomfort, dizziness and cramping may be felt when the Mirena IUD is inserted, but these side effects are short-lived.
Pelvic Inflammatory Disease
Pelvic inflammatory disease is a rare complication that can occur within the first three weeks of insertion of the Mirena IUD. Side effects of pelvic inflammatory disease are fever, chills, painful sex, lower abdominal pain, unusual vaginal discharge and heavy bleeding.
During insertion there is a small risk the Mirena IUD will puncture the uterine wall, which can lead to infection and damage to other organs. If this occurs, the IUD may not be able to protect you from pregnancy.
The Mirena IUD carries a low risk of spontaneously coming out which could lead to an unexpected pregnancy. Your physician will teach you how to routinely check the IUD for proper placement.
Although Mirena provides protection against pregnancy, it does not protect you against sexually transmitted diseases (STDs) such as HIV, herpes and chlamydia. If you are at risk for STDs use an additional form barrier, such as a condom, to increase STD protection.