PIP: Nonoxynols are ethoxylated alkyl phenols or nonylphenylethers. Many condoms contain nonoxynol-9, a nonionic, surfactant-effective spermicide with a very low rate of toxic effects in humans. It is a very rare sensitizer which is compatible with latex and silicone lubricants used in condoms in a range of 1-12%. Nonoxynol-9 is also microbicidal against many organisms including HIV, the herpes viruses, Gonococcus, Treponema, Trichomonas, and hepatitis B. The unique case of a 32-year-old man experiencing allergic contact dermatitis to nonoxynol-9 is reported. A female allergic reaction was, however, reported in Holland, while several cases of allergic reactions to nonoxynol compounds have been reported in Belgium. Nonoxynol is also known to potentially cause allergic contact dermatitis when encountered in waterless hand cleansers and in detergents. The author notes that individuals experiencing irritation from high concentrations of nonoxynol should try a product with a lower concentration. Concern has been expressed that nonoxynol-9 through its detergent action and cytotoxicity may digest nonspecific protective mucosal coatings and induce hyperemia which by itself might promote HIV and other viral infections. Neither the safety nor efficacy of spermicides in preventing sexually transmitted infections in the anal canal or oropharynx has been studied.