How Spermicidal Methods Work
Foam, suppositories, the sponge, creams and jellies, and VCF all contain a spermicide, a chemical that kills sperm. When foam is inserted with the applicator, it rapidly covers the vaginal walls and the cervical os, or opening to the uterus (see Figure 10.5). Contraceptive vaginal suppositories take about 20 minutes to dissolve and cover the walls. One brand of suppository, Encare, effervesces and creates foam inside the vagina; other brands melt. Once VCF is inserted into the vagina, next to the cervix, it dissolves into a stay-in-place gel.