The following most serious adverse reactions associated with the use of Mirena (levonorgestrel-releasing intrauterine system) are discussed in greater detail in the Warnings and Precautions section (5):

• Ectopic Pregnancy [see WARNINGS AND PRECAUTIONS]
• Intrauterine Pregnancy [see WARNINGS AND PRECAUTIONS]
• Group A streptococcal sepsis (GAS) [see WARNINGS AND PRECAUTIONS]
• Pelvic Inflammatory Disease [see WARNINGS AND PRECAUTIONS]
• Embedment [see WARNINGS AND PRECAUTIONS]
• Perforation [see WARNINGS AND PRECAUTIONS]
• Breast Cancer [see WARNINGS AND PRECAUTIONS]

Clinical Trial Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical studies of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

The data provided reflect the experience with the use of Mirena (levonorgestrel-releasing intrauterine system) in the adequate and well-controlled studies for contraception (n=2,339) and heavy menstrual bleeding (n=80). For the contraception indication, Mirena (levonorgestrel-releasing intrauterine system) was compared to a copper IUD (n=1,855), to another formulation of levonorgestrel intrauterine system (n=390) and to a combined oral contraceptive (n=94) in women 18 to 35 years old. The data cover more than 92,000 woman-months of exposure. For the treatment of heavy menstrual bleeding indication (n=80), the subjects included women aged 26 to 50 with confirmed heavy bleeding and exposed for a median of 183 treatment days of Mirena (levonorgestrel-releasing intrauterine system) (range 7 to 295 days). The frequencies of reported adverse drug reactions represent crude incidences.

The adverse reactions seen across the 2 indications overlapped, and are reported using the frequencies from the contraception studies.

The most common adverse reactions ( ≥ 5% users) are uterine/vaginal bleeding alterations (51.9%), amenorrhea (23.9%), intermenstrual bleeding and spotting (23.4%), abdominal/pelvic pain (12.8%), ovarian cysts (12%), headache/migraine (7.7%), acne (7.2%), depressed/altered mood (6.4%), menorrhagia (6.3%), breast tenderness/pain (4.9%), vaginal discharge (4.9%) and IUD expulsion (4.9%).

Other relevant adverse reactions occurring in < 5% of subjects include nausea, nervousness, vulvovaginitis, dysmenorrhea, back pain, weight increase, decreased libido, cervicitis/Papanicolaou smear normal/class II, hypertension, dyspareunia, anemia, alopecia, skin disorders including eczema, pruritus, rash and urticaria, abdominal distention, hirsutism and edema.

Postmarketing Experience

The following adverse reactions have been identified during post approval use of Mirena (levonorgestrel-releasing intrauterine system) : device breakage and angioedema. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Read the Mirena (levonorgestrel-releasing intrauterine system) Side Effects Center for a complete guide to possible side effects »

Drugs or herbal products that induce enzymes, including CYP3A4, that metabolize progestins may decrease the serum concentrations of progestins.

Some drugs or herbal products that may decrease the serum concentration of levonorgestrel include:

• barbiturates
• bosentan
• carbamazepine
• felbamate
• griseofulvin
• oxcarbazepine
• phenytoin
• rifampin
• St. John's wort
• topiramate

Significant changes (increase or decrease) in the serum concentrations of the progestin have been noted in some cases of co-administration with HIV protease inhibitors or with non-nucleoside reverse transcriptase inhibitors.

Consult the labeling of all concurrently used drugs to obtain further information about interactions with Mirena (levonorgestrel-releasing intrauterine system) or the potential for enzyme alterations.

Last reviewed on RxList: 12/20/2010
This monograph has been modified to include the generic and brand name in many instances.