Nonoxynol-9 (N-9) is used in contraceptives for its spermicidal properties (it kills sperm on contact). It was once promoted as a backup method for avoiding pregnancy and as protection against STIs if a condom failed. However, nonoxynol-9 does not provide additional protection against HIV or other STIs.
Research in the 1990s and early 2000s found that nonoxynol-9 can damage the delicate lining of the rectum/arse. It offers no additional protection against STIs and may increase the risk of HIV infection, particularly with frequent use.
Avoid condoms and lubricants containing nonoxynol-9, including those described as spermicidally lubricated. Check the packaging. If an N-9-lubricated condom is the only condom available, using it is preferable to having sex without a condom.
West of Scotland Sexual Health Clinical Guidelines | NHS Scotland |Reviewed September 2025
Lubricants containing N-9 may enhance rectal transmission of HIV and other STIs | Contraception, 2004 | 70(2):107-110David M Phillips, Kristin M Sudol, Clark L Taylor, Laura Guichard, Robert Elsen, Robin A Maguire
Confusion over use of nonoxynol-9 among gay men in San Francisco despite public warnings | 2003 | NAM Aidsmap
Nonoxynol-9 ineffective in preventing HIV infection | World Health Organisation | 28 Jun 2002 Nonoxynol 9 | Wikipedia
