Global Campaign for Microbicides


Rectal Use of N-9

N-9 is found in a wide range of lubricants.

Nonoxynol-9, the same active ingredient found in over the counter birth control products, is still found in some sexual lubricants and on spermicidally lubricated condoms.  The Call to Discontinue Rectal Use of Nonoxynol-9 succeeded in persuading most lubricant manufacturers and many condom manufacturers to stop adding N-9 to their products.  But some manufacturers resisted the call and continue to produce lubricants and condoms containing N-9.

In the 1980s, at the height of concern over AIDS, manufacturers of lubricants and condoms began adding N-9 to their products in an effort to attract more customers. They were hoping to capitalise on the widespread perception that nonoxynol-9 might offer "extra protection" against STIs and HIV. Although the manufacturers could not make an explicit claim of effectiveness (because they had not done the required clinical trials), the word on the street was that N-9 containing lubricants provided extra protection for "safer sex."  On this page, you will find: 

Products containing Nonoxynol-9 should NOT be used for rectal sex.

Studies in humans and in mice suggest that using N-9 containing products in the rectum may actually increase an individual's risk of HIV rather than offer "extra protection."

David Phillips and colleagues of the Population Council in New York City tested the effect of lubricants containing N-9 on the rectal epithelium of 4 human volunteers: three men and one woman. Each participant was asked to use four different products: two over-the-counter lubricants containing N-9-KY Plus and Fore Play --and two gels that do not contain N-9. After retaining the product in the rectum for 15 minutes, the participants used saline to wash out the rectum and collected the specimen for analysis. Eight to ten hours later, participants collected another lavage specimen and then waited three days before testing the next product.

The specimens from the N-9 products contained hundreds of sheets of epithelial cells, large enough to be seen with the naked eye. The N-9 had caused the entire rectal epithelium to slough off. No such sloughing was apparent with the control products.

The authors concluded "removal of the rectal epithelium may enhance HIV infection because the primary target cells of HIV, lympocytes and macrophages, are located in the lamina propria immediately below the rectal epithelium."

Interestingly, the rectal epithelium seemed to have repaired itself within 8 hours, a result that could explain why an earlier study of Advantage-S --a spermicide containing 52mg of N-9-- was not associated with rectal epithelial disruption. In this study, scientists took biopsies of the rectal epithelium 12 hours after rectal use of Advantage-S. Phillips and colleagues believe that the rectal epithelium, which rapidly repairs itself after damage, had already had an opportunity to heal in these participants.

Data from studies of HSV in mice and monkeys reinforce concern about rectal use of N-9.

Significantly, N-9 containing products protect mice and monkeys from viral infection when they are used vaginally, but these same products appear to increase infection when applied rectally.

Vaginal application of N-9 products protected Rhesus macques from infection with simmian immunodeficiency virus (SIV), a cousin of HIV, and protected mice from herpes virus (HSV-2), another virus structurally similar to HIV. But when applied in the rectum of mice, products containing N-9 caused rapid sloughing of epithelial cells and dramatically increased the risk of infection with HSV-2.

The damage associated with rectal use of N-9 products is far more extensive and worrisome than that observed with vaginal use of the same products.

Lubricant use is common among individuals practicing anal sex.

Studies show that most men who have sex with men (MSM) use lubricants during anal intercourse and some still actively seek out products containing nonoxynol-9. Among 3,093 gay men who had had intercourse in the last 6 months, Gross et al (1998) found that more than three-fourths used lubricants more than 80% of the time. Among them, 41% actively sought products containing Nonoxynol-9.

In a similar study among Latino MSM in New York City, 93% used lubricants during anal sex, including many men who did not use condoms. Almost 50% of respondents report applying lubricant "inside" the rectum (Carballo-Dieguez et al 2000). Most men who had heard of Nonoxynol-9 had favourable associations regarding its potential to protect --an impression that is contrary to available data.

Women and heterosexual couples also practice anal intercourse

Studies from the United States indicate that anywhere from 6 to 13% of women report engaging in anal sex within the last year (Gross et al 2000). In a six-city study of women at high risk of HIV, 32% reported anal sex in the previous 6 months (Gross et al, 2000).

Anal sex may also be more common among women in developing countries than previously thought. A Chinese study of 1300 people from 41 cities found that nearly 70 percent of men and women had engaged in anal intercourse (Burton 1990). The frequency of anal intercourse has also been documented among heterosexuals in Latin America and South Africa (Kelly 2001).