Spermicide is a contraceptive substance that destroys 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. Usually, spermicides are combined with contraceptive barrier methods such as diaphragms, condoms, cervical caps, and sponges. Combined methods are believed to result in lower pregnancy rates than either method alone.
Spermicides are typically unscented, clear, unflavored, non-staining, and lubricative.
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. Used alone, spermicides have a perfect use failure rate of 6% per year when used correctly and consistently, and 16% failure rate per year in typical use.
Spermicide brands
This list of examples was provided by the Mayo Clinic: VCF Vaginal Contraceptive Film VCF Vaginal Contraceptive Gel VCF Contraceptive Foam Conceptrol Crinone Encare Endometrin First-Progesterone VGS Gynol II Prochieve Today Sponge Vagi-Gard Douche Non-Staining
Nonoxynol-9 is the primary chemical in spermicides to inhibit sperm motility. Active secondary spermicidal ingredients can include octoxynol-9, benzalkonium chloride and menfegol. These secondary ingredients are not mainstream in the United States, where nonoxynol-9 alone is typical. Preventing sperm motility will inhibit the sperm from travelling towards the egg moving down the fallopian tubes to the uterus. The deep proper insertion of spermicide should effectively block the cervix so that sperm cannot make it past the cervix to the uterus or the Fallopian tubes. A study observing the distribution of spermicide containing nonoxynol-9 in the vaginal tract showed “After 10 min the gel spread within the vaginal canal providing a contiguous covering of the epithelium of variable thickness.” The sole goal of spermicide is to prevent fertilization.
Menfegol is a spermicide manufactured as a foaming tablet. It is available only in Europe.
Octoxynol-9 was previously a common spermicide, but was removed from the U.S. market in 2002 after manufacturers failed to perform new studies required by the FDA.
The spermicides benzalkonium chloride and sodium cholate are used in some contraceptive sponges. Benzalkonium chloride might also be available in Canada as a suppository.
The 2008 Ig Nobel Prize (a parody of the Nobel Prizes) in Chemistry was awarded to Sheree Umpierre, Joseph Hill, and Deborah Anderson, for discovering that Coca-Cola is an effective spermicide, and to C.Y. Hong, C.C. Shieh, P. Wu, and B.N. Chiang for proving it is not.
Lemon juice solutions have been shown to immobilize sperm in the laboratory, as has Krest Bitter Lemon drink. While the authors of the Krest Bitter Lemon study suggested its use as a postcoital douche, this is unlikely to be effective, as sperm begin leaving the ejaculate (out of the reach of any douche) within 1.5 minutes of deposition. No published studies appear to have been done on the effectiveness of lemon juice preparations in preventing pregnancy, though they are advocated by some as 'natural' spermicides.
Lactic acid preparations have also been shown to have some spermicidal effect, and commercial lactic acid-based spermicides are available. A contraceptive containing lactic acid, citric acid, and potassium bitartrate (Phexxi) was approved for use in the United States in May 2020.
Extractives of the neem plant such as neem oil have also been proposed as spermicides based on laboratory studies. Animal studies of creams and pessaries derived from neem have shown they have contraceptive effects; however, trials in humans to determine its effectiveness in preventing pregnancy have not yet been conducted.
Use with condoms
Spermicides are believed to increase the contraceptive effectiveness of condoms.
However, condoms that are spermicidally lubricated by the manufacturer 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 over no condom at all.
Spermicides used alone are only about 91 percent effective. When spermicides are used in conjunction with condoms and other barrier methods there is a 97 percent effective rate for pregnancy prevention.