A common spermicide gel which has previously been proposed as a preventative agent against HIV-1 infection has been shown to be ineffective, according to authors of a study in this week’s issue of THE LANCET-and could actually increase HIV-1 transmission if used frequently.

Nonoxynol-9 is an inexpensive over-the-counter spermicide; laboratory studies have suggested that it could be a barrier to HIV-1 infection and other sexually transmitted diseases, although previous studies among women have been inconclusive. To clarify the effectiveness of Nonoxynol-9 spermicide, Lut Van Damme from the Institute of Tropical Medicine, Antwerp, Belgium (currently affiliated with CONRAD, Arlington, VA, USA), and colleagues did a randomised trial among HIV-1-negative female sex workers in South Africa, Côte d’Ivoire, Benin, and Thailand.

Data from 765 women were included in the primary analysis. Around a third of women used the spermicide gel an average of three and a half times a day, which was associated with a doubling of HIV-1 infection compared with women using a placebo gel. The main hypothesis for the observed effect was the occurrence of vaginal lesions as a result of intensive Nonoxynol-9 use. Low use of Nonoxynol-9 gel did not increase the risk of HIV-1 infection; there were no differences in incidence of other sexually transmitted diseases between Nonoxynol-9 and placebo gels.

Lut Van Damme comments: “Nonoxynol-9 no longer has a part to play in HIV-1-prevention. Our data show that low frequency use of nonoxynol-9 causes neither harm nor benefit; but that frequent use increases a woman’s risk of HIV-1 infection by causing lesions.”

In an accompanying Commentary (p 962), David Wilkinson from the University of South Australia, Adelaide, Australia, concludes: “It is vitally important that the global effort to develop an effective vaginal microbicide that reduces the risk of acquisition of HIV (and preferably other sexually acquired infections) among women does not lose any momentum as a result of the negative results of the van Damme trial…The concept is sound, the need is great, and many important lessons have been learned: the search continues.”