Spermicide is a substance that contains chemicals, such as nonoxynol-9, that immobilize or kill sperm. Spermicide is put into the vagina before sex to prevent sperm from entering the uterus. Spermicide is available without a prescription and comes in many forms, including cream, gel, foam, film, suppository and tablet.
Spermicide isn't a highly effective birth control method when used alone. However, spermicide can also be used with a barrier method — such as a condom, diaphragm or cervical cap — to prevent pregnancy. Spermicide doesn't offer protection from sexually transmitted infections.