Most Common Side Effects of Mirena (Levonorgestrel-releasing Intrauterine System)
The most common side effect of Mirena is irregular bleeding or spotting during the first few months after insertion, with many women eventually experiencing reduced menstrual bleeding or amenorrhea over time. 1
Bleeding Pattern Changes
Bleeding pattern changes are the most frequently reported side effects with Mirena:
Initial phase (first 3-6 months):
Long-term effects (after 6-12 months):
Other Common Side Effects
Beyond bleeding changes, other side effects may include:
- Breast tenderness 4, 5
- Abdominal/pelvic pain 3, 5
- Headache 4
- Acne 4, 5
- Mood changes 5
- Transient ovarian cysts 4
Potential Complications
Less common but important to note:
- Device expulsion (occurs in approximately 3-10% of users) 3
- Device dislocation 4
- Risk of pelvic inflammatory disease (PID) is highest in the first 20 days after insertion 2
Management of Side Effects
For women experiencing troublesome bleeding irregularities:
- NSAIDs for short-term treatment (5-7 days) can help manage heavy or prolonged bleeding 2
- Reassurance that bleeding irregularities are generally not harmful and often improve with continued use 2
- If bleeding persists and is unacceptable to the patient, alternative contraceptive methods should be considered 2
Clinical Considerations
- Counseling before insertion about expected bleeding pattern changes is essential to improve continuation rates 2
- Amenorrhea is not harmful and does not require medical treatment 2
- If a woman's regular bleeding pattern changes abruptly to amenorrhea, pregnancy should be ruled out if clinically indicated 2
- Mirena has a failure rate of less than 1%, making it one of the most effective contraceptive methods available 2
It's worth noting that despite these side effects, Mirena has high continuation rates (80% at one year) 2, indicating that most women find the benefits outweigh the side effects, particularly those seeking treatment for heavy menstrual bleeding 3.