From the manufacturer
Preventeza, from the makers of Vagisil, is an emergency contraceptive that reduces the chance of pregnancy after unprotected sex if a contraceptive failed or if you did not use birth control. Available over the counter. One step by taking one tablet. The tablet contains levonorgestrel, a hormone that has been used in many birth control pills for several decades. It contains a higher dose of levonorgestrel than birth control pills, but works in a similar way to prevent pregnancy, mainly by preventing ovulation (egg release). It may also prevent fertilization of a released egg (joining of sperm and egg) or attachment of a fertilized egg to the uterus (implantation).