Mirena (Levonorgestrel)

Mirena, a levonorgestrel‑releasing intrauterine system, is used in the reproductive health field for contraception and menstrual management.

• Contraception: provides highly effective, reversible birth control for up to five years.
• Heavy menstrual bleeding: reduces menstrual blood loss and improves anemia associated with menorrhagia.
• Endometrial hyperplasia (benign): may be used as part of management to suppress endometrial proliferation.
• Hormone‑dependent uterine bleeding: helps regulate irregular bleeding patterns caused by hormonal fluctuations.

• Mirena releases levonorgestrel directly into the uterine cavity, where the hormone thickens cervical mucus, impairs sperm motility and viability, suppresses endometrial proliferation, and may inhibit ovulation. This localized action creates a hostile environment for fertilization while simultaneously reducing menstrual blood flow.

Adverse reactions reported with Mirena are categorized by frequency.

Common Side Effects

• Irregular bleeding or spotting: changes in bleeding pattern during the first months.
• Amenorrhea: absence of menstrual periods after continued use.
• Pelvic pain or cramping: discomfort related to device insertion or presence.
• Headache: mild to moderate headache episodes.

Serious or Rare Side Effects

• Uterine perforation: rare injury to the uterine wall during insertion.
• Expulsion of the device: device may be partially or completely expelled.
• Pelvic inflammatory disease: infection that can develop after insertion.

Mirena requires careful patient selection and follow‑up to minimize risks.

• Contraindication: Do not use in women who are pregnant or have known or suspected pregnancy.
• Screening: Verify absence of active pelvic infection before insertion.
• Follow‑up: Schedule pelvic examination 4–6 weeks after insertion to confirm placement.
• Removal: Ensure device is removed promptly if pregnancy occurs or if serious complications arise.
• Patient counseling: Inform about possible changes in bleeding pattern and signs of infection.
• Store at ambient temperature: keep the device in its original packaging, protect from moisture and direct sunlight.

Mirena may interact with drugs that affect levonorgestrel metabolism.

Major Interactions (Avoid)

• Antiepileptic enzyme inducers (e.g., carbamazepine, phenytoin): may reduce levonorgestrel effectiveness.
• Rifampin: can decrease levonorgestrel concentrations, risking contraceptive failure.

Moderate Interactions (Monitor Closely)

• Antifungal azoles (e.g., ketoconazole): may increase levonorgestrel levels, potentially heightening side effects.
• Antiretroviral protease inhibitors: may alter hormone metabolism, requiring clinical monitoring.
• Hormonal therapies (e.g., estrogen‑containing contraceptives): concurrent use may increase risk of thromboembolic events.