It prevents pregnancy by preventing the man's semen from entering the woman's vagina. Spermicidal foam containing nonoxynol-9 also kills the HIV virus. Some condoms are coated with a small amount of spermicide. Although researchers agree that using two contraceptive methods together enhances protection against pregnancy, they have been unable to determine how much additional protection is afforded by the addition of a small amount of spermicide to the condom. It is safest to have a contraceptive foam barrier right at the cervix.
Several spermicides are available for use with condoms.
Contraceptive foam, a spermicidal agent in an aerosol form, is inserted deep in the vagina with a small applicator and is an excellent choice for use with the condom. A contraceptive cream or jelly may also be inserted deep in the vagina with a small applicator, but contraceptive creams and jellies were primarily designed to be used in conjunction with a diaphragm, not a condom. Because of this, intercourse should be delayed 15 minutes after insertion to allow for this foaming action to occur. And Using Them Effectively Use latex condoms only . All condoms are not the same.