Nonoxynol-9 (N-9) is the most common active ingredient in spermicide. Spermicides which contain N-9 come in many forms such as gels, films and foams.

Nonoxynol-9 is an organic compound that is used as a surfactant and is a member of nonoxynol family of nonionic surfactants. Cleaning and cosmetic products often contain N-9 and related compounds. When researchers observed nonoxynol-9’s ability to kill microbes in vitro, they initially thought it could be used to prevent the transmission of sexual transmitted diseases (STDs). Even the NHS in the UK got on board and prescribe Gygel as an N9 based spermicide.

More recent research however, has found that N-9 might actually increase a person’s risk of contracting STDs, especially when frequently used. Researchers came to this conclusion after noticing that the harsh chemicals in N-9 causes tiny abrasions inside the sensitive vaginal and anal walls.

Quoting from Wikipedia:

"From 1996 to 2000, a UN-sponsored study conducted in several locations in Africa followed nearly 1,000 sex workers who used nonoxynol-9 gels or a placebo. The HIV infection rate among those using nonoxynol-9 was about 50% higher than those who used the placebo; those using nonoxynol-9 also had a higher incidence of vaginal lesions, which may have contributed to this increased risk. Whereas these results may not be directly applicable to lower-frequency use, these findings combined with lack of any demonstrated HIV-prevention benefit from nonoxynol-9 use led the World Health Organization to recommend that it no longer be used by those at high risk of HIV infection. The WHO further notes that "Nonoxynol-9 offers no protection against sexually transmitted infections such as gonorrhoea, chlamydia."[3] A 2006 study of a nonoxynol-9 vaginal gel in female sex workers in Africa concluded that it did not prevent genital human papillomavirus (HPV) infection and could increase the virus's ability to infect or persist"

For those of you who are unaware of the potential side effects and health risks associated with N-9, you can check out some good information on the following sites:

World Health Organization

Planned Parenthood