Levonorgestrel

Levonorgestrel is a progestogen used in several contraceptive and hormonal indications.

• Emergency contraception: Provides a high‑dose regimen to prevent pregnancy after unprotected intercourse.
• Progestin‑only contraception: Maintains contraceptive efficacy when taken daily as a single‑dose pill.
• Hormone therapy: Supplies progestogenic activity for certain hormone replacement regimens.

• Levonorgestrel binds to progesterone receptors in the hypothalamus and pituitary, suppressing the luteinizing hormone surge and thereby preventing ovulation. It also induces changes in cervical mucus that impede sperm penetration and alters the endometrial lining, reducing the likelihood of implantation should fertilisation occur.

Levonorgestrel may cause a range of adverse reactions, most of which are mild and transient.

Common Side Effects

• Nausea: mild to moderate stomach upset.
• Headache: tension‑type or migraine‑like pain.
• Breast tenderness: discomfort or swelling of the breasts.
• Irregular bleeding: spotting or changes in menstrual flow.
• Mood changes: irritability or emotional fluctuations.
• Abdominal pain: cramping or discomfort.

Serious or Rare Side Effects

• Thromboembolic events: deep‑vein thrombosis or pulmonary embolism.
• Severe allergic reaction: anaphylaxis, hives, or swelling of the face.
• Liver dysfunction: jaundice or elevated liver enzymes.
• Pregnancy complications: if taken during early pregnancy, may affect fetal development.

Before prescribing Levonorgestrel, clinicians should consider several safety aspects.

• Medical review: assess for active thromboembolic disease, severe liver impairment, or known hypersensitivity.
• Pregnancy status: avoid use in confirmed pregnancy unless benefits outweigh risks.
• Breastfeeding: evaluate risk‑benefit, as drug may pass into milk.
• Concomitant medications: review drugs that may reduce efficacy, such as enzyme inducers.
• Patient counseling: advise on possible menstrual changes and when to seek medical help.
• Store at ambient temperature: keep below 25°C, retain in original packaging, protect from moisture and direct sunlight.

Levonorgestrel can interact with other medicines, altering its effectiveness or safety profile.

Major Interactions (Avoid)

• Antiepileptic enzyme inducers (e.g., carbamazepine, phenytoin): may markedly reduce contraceptive efficacy.
• Rifampicin: decreases plasma concentrations, compromising pregnancy prevention.
• St. John’s wort: herbal inducer that can lower drug levels.

Moderate Interactions (Monitor Closely)

• Antifungal azoles (e.g., ketoconazole): may increase levonorgestrel exposure, raising side‑effect risk.
• Protease inhibitor antiretrovirals: can alter metabolism, requiring clinical monitoring.
• Estrogen‑containing hormonal therapies: may affect bleeding patterns and overall hormonal balance.