Mirena (Levonorgestrel)

Levonorgestrel released from Mirena acts within the reproductive hormonal axis to deliver long‑term contraception and therapeutic control of uterine bleeding.

• Contraception: Provides highly effective, reversible birth control for women of reproductive age.
• Heavy menstrual bleeding: Reduces menstrual blood loss and improves anemia associated with excessive bleeding.
• Endometrial protection: Prevents estrogen‑induced endometrial hyperplasia in women receiving combined hormone therapy.

• Mirena continuously releases a low dose of levonorgestrel directly into the uterine cavity. Levonorgestrel binds to progesterone receptors in the endometrium, leading to endometrial atrophy, thickening of cervical mucus, and suppression of the luteinizing hormone surge, which together inhibit ovulation and create an environment hostile to sperm and implantation.

Levonorgestrel delivered via Mirena may be associated with a range of local and systemic adverse reactions.

Common Side Effects

• Irregular bleeding or spotting
• Amenorrhea (absence of periods)
• Cervical discharge
• Headache
• Breast tenderness
• Acne

Serious or Rare Side Effects

• Uterine perforation
• Pelvic inflammatory disease
• Ectopic pregnancy
• Ovarian cyst formation
• Hormone‑dependent tumor growth
• Allergic reaction (e.g., rash, anaphylaxis)

• Prior to insertion and during use, several precautions should be observed to ensure safety and optimal performance of Mirena.
• Screen for contraindications: Ensure patient has no active pelvic infection, unexplained vaginal bleeding, or known hypersensitivity to levonorgestrel.
• Pregnancy status: Confirm patient is not pregnant before insertion.
• Timing of insertion: Insert within 5 days of menstrual onset or after a negative pregnancy test.
• Follow‑up: Schedule evaluation 4–6 weeks post‑insertion to assess placement and bleeding pattern.
• Removal considerations: Remove before expiry (5 years) or if complications arise.
• Store at room temperature: Keep device in original packaging, protect from moisture and direct sunlight.

Levonorgestrel may interact with other medicines that affect its metabolism or hormonal activity.

Major Interactions (Avoid)

• Enzyme inducers (e.g., rifampin, carbamazepine): May reduce levonorgestrel effectiveness.
• Antifungal azoles (e.g., ketoconazole): May increase systemic levonorgestrel levels.
• Antiretroviral drugs (e.g., efavirenz): May lower contraceptive efficacy.

Moderate Interactions (Monitor Closely)

• Hormonal therapies (e.g., combined oral contraceptives): May alter bleeding patterns.
• Antibiotics (e.g., tetracycline): Limited evidence of interaction, monitor for breakthrough bleeding.
• Herbal supplements (e.g., St. John’s wort): Potential enzyme induction, observe efficacy.