Spermicide

Spermicide is a substance that kills sperm, inserted vaginally prior to intercourse to prevent pregnancy. As a contraceptive, spermicide may be used alone. However, the pregnancy rate experienced by couples using only spermicide is higher than that of couples using other methods.

Spermicides are usually combined with contraceptive barrier methods such as diaphragms, condoms, cervical caps, or sponges. Combined methods are believed to result in lower pregnancy rates than either method alone.

Types and effectiveness
The most common active ingredient of spermicides is nonoxynol-9. Spermicides containing nonoxynol-9 are available in many forms, such as jelly (gel), films, and foams. Contraceptive Technology states that spermicides have a failure rate of 18% per year when used correctly and consistently, and 29% under typical use.

Menfegol is a spermicide manufactured as a foaming tablet. It is only available in Europe.

The spermicides benzalkonium chloride and sodium cholate are used in some contraceptive sponges.

Use as microbicide
Previously, it was believed that nonoxynol-9 reduced the risk of HIV infection, as it prevents transmission of the virus in the laboratory. However, many human studies have shown no protective effect. Because nonoxynol-9 creates abrasions in the vaginal and rectal walls, it may even make transmission of HIV and other STDs more likely, especially if used frequently.

Use with condoms
Some condoms are lubricated at the manufacturing plant with a small amount of nonoxynyl-9.

According to Consumer Reports, spermicidally lubricated condoms have no additional benefit in preventing pregnancy, have a shorter shelf life, and may cause urinary-tract infections in women.

The World Health Organization says that spermicidally lubricated condoms should no longer be promoted. However, they recommend using a nonoxynol-9 lubricated condom compared to no condom.

In contrast, application of separately packaged spermicide is believed to increase the contraceptive efficacy of condoms.

Side effects
Nonoxynyl-9 has a number of possible side effects, but they are uncommon. These include irritation, itching, or burning of the sex organs (either partner), and in women, urinary tract infections, yeast infection, and bacterial vaginosis.