Levonorgestrel tablets are a type of emergency contraception commonly known as the morning-after pill. They contain a synthetic hormone called levonorgestrel, which is similar to the hormone progesterone that is naturally produced by the ovaries. The tablets are taken within 72 hours of unprotected sex or contraceptive failure to prevent pregnancy. Levonorgestrel tablets work by preventing or delaying ovulation, which is the release of an egg from the ovary. They may also thicken the cervical mucus, making it more difficult for sperm to reach the egg.