Dear Alice,

I have heard that the chemical nonoxynol-9 increased the chance of getting AIDS. Recently, I came across a product with octoxynol-9 in it. I wonder the difference between the two chemicals. Do they both increase HIV risk?

Dear Reader,

You heard right — here's the scoop: The Joint United Nations Programme on HIV/AIDS (UNAIDS) conducted a four-year study on the effectiveness of nonoxynol-9 (N-9) gel as a microbicide (a chemical substance that kills viruses and bacteria) against HIV. The study found that the women who used N-9 were not only unprotected from HIV, but became infected with the virus at an approximately 50 percent higher rate than the placebo-gel-using participants. These research results suggest that N-9 may have facilitated HIV transmission. Previous studies have shown N-9's potential to irritate or cause lesions in the tender mucous membranes of the rectum and vagina in some users, increasing the likelihood of the transfer of HIV.

In light of these findings, the World Health Organization and the Centers for Disease Control and Prevention (CDC) do not recommend using nonoxynol-9 to prevent sexually transmitted infections (STIs), including HIV, during vaginal or anal sex. Condoms (without N-9) are recommended as the most effective form of STI prevention for people who are sexually active.

Some condoms are lubricated with N-9, with the intention of increasing their effectiveness in preventing pregnancy. However, there is currently no evidence that condoms with N-9 are any more effective in preventing pregnancy than condoms without N-9. When used correctly and consistently, condoms alone are 98 percent effective at preventing pregnancy. Read Common reasons for condom failure and Condom breakage and slippage in Alice's Sexual Health archive for details on correct and consistent use of condoms to help avoid the most common reason for condom failure — human error. N-9 is also used alone as a method of pregnancy prevention. It's available as creams, films, foams, gels, and suppositories. N-9 is significantly more effective as birth control when it's used with a barrier method such as the diaphragm or cervical cap.

If you use IV drugs, aren't in a long-term monogamous relationship, or don't know if your partner(s) has been tested recently for STIs, it's recommended that you use condoms to protect against STIs. If you choose to use condoms with N-9, you're probably not putting yourself at serious risk of HIV infection unless you use them many times a day. Using a condom with N-9 is a better option than no condom at all.

You mention octoxynol-9 (O-9) in your question. O-9 is in the same class of microbicides as N-9, but it's made with a different chemical. It's available on the market in the United States and Canada as a contraceptive jelly or cream, but it's hard to find. People who use spermicide along with another form of contraception, such as a diaphragm or cervical cap, may choose O-9 if they experience irritation, allergies, and/or other side effects from using N-9. Because octoxynol-9 is much less common and less research about it exists, the relationship between O-9 and HIV isn't clear. You might want to be on the safe side and follow similar guidelines as for N-9.

If you have concerns about birth control or STI prevention, a discussion with your health care provider can help you sort through your choices. In short, your best protection against STIs is a condom. Some people at low risk for becoming infected with HIV (those in a monogamous, long-term relationship who don't use IV drugs) may decide to use N-9 or O-9 as a method of pregnancy prevention, a choice made more effective if used in combination with a condom, diaphragm, or cervical cap.

Thanks for inquiring,  


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