The contraceptive sponge combines barrier and spermicidal methods to prevent conception. Sponges work in two ways. First, the sponge is inserted into the vagina, so it can cover the cervix and prevent any sperm from entering the uterus. Secondly, the sponge contains spermicide.^[2]

The sponges are inserted vaginally prior to intercourse and must be placed over the cervix to be effective. Sponges provide no protection from sexually transmitted infections. Sponges can provide contraception for multiple acts of intercourse over a 24-hour period, but cannot be reused beyond that time or once removed.^[3]

Sponge's effectiveness is 91% if used perfectly by women who never gave birth, and 80% if used perfectly by women who have given at least one birth. Since it is hard to use the sponge perfectly every time having vaginal sex, its real effectiveness can be lower, and it is advised to combine sponges with other birth control methods, like withdrawal of penis before ejaculation or condoms.^[4]

To use the sponge, wet the sponge and squeeze it, fold it and put it in the vagina covering the cervix. A sponge works for 24 hours once put in, during which the female can have sex multiple times. Once the sponge is pulled out, it should not be reused and should be trashed, not flushed. The sponge should be left in place for 6 hours after having sex. A sponge should not be in the vagina for more than 30 hours.^[5]

Sponges are a physical barrier, trapping sperm and preventing their passage through the cervix into the reproductive system. The spermicide is an important component of pregnancy prevention.

People sensitive to Nonoxynol-9, an ingredient in the spermicide used in the sponge, may experience unpleasant irritation and may face increase risk of sexually transmitted infections. Sponge users may have a slightly higher risk of toxic shock syndrome.^[6]

• Shortly after they were taken off the U.S. market, the sponge was featured in an episode of the sitcom Seinfeld titled "The Sponge". In the episode, Elaine Benes conserves her remaining sponges by choosing to not have intercourse unless she is certain her partner is "sponge-worthy".^[7]