Nonoxynol-9, is an organic compound that is used as a surfactant and vaginal spermicide used for contraception in spermicidal creams, jellies, foams, gel, and lubricants. It is also used in conjuction with other methods of contraception, including condoms, cervical caps and diaphragms. Nonoxynol-9 interacts with the lipids in the membranes of the acrosome and the midpiece of the sperm. The sperm membranes are lysed; the acrosome, neck and midpiece of the spermatozoa are loosened and then detached which results in their immobilization and death. Nonoxynol-9 offers no protection against sexually transmitted infections such as gonorrhoea, chlamydia and does not prevent HIV infection and may even favour infection if used frequently. A possible reason, is that nonoxynol-9 can disrupt the epithelium, or wall, of the vagina, thereby potentially facilitating invasion by an infective organism and virus. Nonoxynol-9 and related compounds are ingredients in various cleaning and cosmetic products.