Lenor Emergency Contraceptive is a morning-after pill (MAP) effective within 72 hours, or 3 days, after sex. It contains 1.5 milligrams of levonorgestrel, which is used in lower doses, in many birth control pills. It is a single-dose pill.
Emergency contraception is effective only in the first few days following intercourse, before the ovum is released from the ovary and before the sperm fertilizes the ovum. Emergency contraception cannot interrupt an established pregnancy or harm a developing embryo.