What it does
Levonorgestrel is a medication commonly used for preventing pregnancy after unprotected sex or contraceptive failure.
Commonly used for: emergency contraception, postcoital contraception
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Source: Pharmacy and Poisons Board · fetched 2026-01-28 21:51:13 · updated 2026-03-23 04:36:19
About this medicine
Levonorgestrel is a medication commonly used for preventing pregnancy after unprotected sex or contraceptive failure.
What it treats
- emergency contraception
- postcoital contraception
How it works
Levonorgestrel works by preventing ovulation (the release of an egg) and may also prevent fertilization or implantation of a fertilized egg.
Who it's for
This medication is for individuals who have had unprotected sex and want to prevent pregnancy.
AI-assisted summary grounded in BNF data - general information only, not medical advice. Always confirm with your pharmacist or doctor.
Clinical monograph: levonogestrel
Levonorgestrel is a synthetic progestin commonly used in hormonal contraceptives and for emergency contraception. It functions by mimicking the effects of natural progesterone, thereby regulating ovulation and menstruation. It is available in various formulations, including oral tablets and intrauterine devices (IUDs).
Indications
- Contraception
- Emergency contraception
- Management of menstrual disorders
- Endometriosis treatment
Dosage
Children: Refer to specific product guidelines for dosing information.
Adults: Refer to specific product guidelines for dosing information.
Mechanism of action
Levonorgestrel primarily acts by preventing ovulation through the inhibition of luteinizing hormone (LH) surge. It also creates a thickened cervical mucus, which impedes sperm passage, and alters the endometrial lining, making it less suitable for implantation. Additionally, it may affect the motility of the fallopian tubes.
Pharmacodynamics
Levonorgestrel has a high affinity for progesterone receptors, leading to various physiological effects that include the suppression of gonadotropin release and alterations in the endometrial lining. Its progestational effects contribute to the prevention of pregnancy, while its actions on cervical mucus contribute to its contraceptive efficacy.
Pharmacokinetics
Levonorgestrel is rapidly absorbed following oral administration, with peak plasma concentrations typically occurring within 1 to 2 hours. It is extensively metabolized in the liver, primarily by the cytochrome P450 enzyme system. The elimination half-life is approximately 24 hours, and it is primarily excreted in urine and feces. Due to its lipophilic nature, it has a large volume of distribution and is highly protein-bound in plasma.
Contra-indications
- Pregnancy
- Known hypersensitivity to levonorgestrel or any component of the formulation
- Severe liver disease
- Unexplained vaginal bleeding
Adverse effects
- Nausea
- Vomiting
- Fatigue
- Headache
- Dizziness
- Breast tenderness
- Menstrual changes
- Abdominal pain
Interactions
- Enzyme inducers (e.g., rifampicin, certain antiepileptics) may reduce effectiveness
- Antibiotics may have variable effects on hormone levels
- Antiretroviral medications may alter effectiveness
Precautions
- Use with caution in patients with a history of thromboembolic disorders
- Monitor for ectopic pregnancy in women with risk factors
- Consider alternative contraceptive methods in cases of severe gastrointestinal disorders
Pregnancy
Levonorgestrel is contraindicated during pregnancy. It is not an abortifacient and is intended for use as emergency contraception.
Breast-feeding
Levonorgestrel is excreted in breast milk. Use with caution and consult with a healthcare professional if necessary.
Storage
Store at room temperature, away from moisture and heat. Keep out of reach of children.
Formulations
- Levonorgestrel 1.5 mg tablet for emergency contraception
- Levonorgestrel 0.03 mg daily oral contraceptive tablet
AI-synthesized from BNF references - general information only, not a substitute for professional medical advice or the current BNF. Verify doses with a pharmacist.
This drug in other countries
The same active ingredient registered across other registries we cover - including different brands.