Nonoxynol-9, sometimes abbreviated as N-9, is a non-ionic nonoxynol surfactant that is used as an ingredient in various cleaning and cosmetic products, but is also widely used in contraceptives for its spermicidal properties.
Although it was at one time widely promoted as a protection against sexually transmitted infections including HIV, subsequent studies have shown that it can in fact increase the risk of infection by damaging the physical barriers of the rectum or vagina.
A 2004 study found that over a six-month period, the typical-use failure rates for five nonoxynol-9 vaginal contraceptives (film, suppository, and gels at three different concentrations) ranged from 10% to 20%.
However, the 2001 WHO/CONRAD Technical Consultation on Nonoxynol-9 concluded that:
There is no published scientific evidence that N-9-lubricated condoms provide any additional protection against pregnancy or STDs compared with condoms lubricated with other products. Since adverse effects due to the addition of N-9 to condoms cannot be excluded, such condoms should no longer be promoted. However, it is better to use N-9-lubricated condoms than no condoms.
Additionally, the WHO statement suggests that N-9 should not be used rectally under any circumstances.
Most contraceptive sponges contain nonoxynol-9 as an active ingredient.
From 1996 to 2000, a UN-sponsored study carried out in several locations in Africa followed nearly 1000 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.
While 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 have led most major health agencies to recommend that it no longer be used by women at high risk of HIV infection. The WHO further notes that "Nonoxynol-9 offers no protection against sexually transmitted infections such as gonorrhoea, chlamydia."
Nonoxynol-9 based products (including condoms containing the spermicide) should not be used for prevention of HIV or STDs or for contraception between non-monogamous partners because of the increased risk of infection by HIV or sexually transmitted infections. However, non-spermicide condoms are available and are still highly successful at preventing both pregnancy and STD transmission.
Regular use of nonoxynol-9 likely increases the risk of infection with sexually transmitted human papillomaviruses (HPVs) that can cause cervical cancer. In one of the studies, researchers at the National Cancer Institute also reported that the increased likelihood of HPV infection caused by N-9 was mitigated through the use of carrageenan-based lubricants mixed 1:1 with N-9. Two consumer products containing carrageenan, Divine No. 9 and BIOglide, prevented detectable HPV infection in the study.
Frequent use of nonoxynol-9 is linked to higher risk of urinary tract infections (UTIs).
Some people have reported allergic reactions to Nonoxynol-9; however, it is possible to test it oneself on the lymph nodes on the upper thigh by the groin to see if one is hypersensitive. If so, the skin usually turns red and causes a burning sensation. Recovery from an allergic reaction usually takes about 6-8 hours.
For use with a cervical barrier such as a diaphragm, a jelly containing lactic acid may work as a substitute. Lactic acid is known to immobilize sperm, also. But in contrast with nonoxynol-9, this immobilization seems to be reversible and is for that reason less reliable.