Levonorgestrel is a emergency contraceptive pill that prevents unintended pregnancy, primarily by delaying ovulation. It is most effective when taken within 72 hours (3 days) after unprotected sex. It is not a regular birth control method, will not affect an existing pregnancy, and common side effects include nausea, headache, and fatigue.

Key Information & Usage:

• Effectiveness: Works best if taken as soon as possible, ideally within 24 hours, but up to 72 hours post-intercourse.

• Mechanism: Prevents or delays the release of an egg (ovulation).

• Limitations: It is not a long-term contraceptive, should not be used regularly, and is less effective if you are already pregnant.

• Dosage: Generally a single 1.5mg dose. Some regimens may require a second dose 12 hours later if using a 0.75mg formulation.