Evaluating the risk of unprotected oral-vaginal sex (cunnilingus) is difficult, given that most people surveyed in studies did not avoid other types of unsafe sexual activity. However, there has been one case of female-to-female transmission of HIV via cunnilingus and another of female-to-male transmission of HIV via cunnilingus. Both of these cases involved transmission from the partner receiving oral sex to the partner performing oral sex. There haven't been any documented cases of HIV transmission from the insertive partner to the receptive partner.

To reduce the risk:

• Use a latex barrier—such as a natural rubber latex sheet, a dental dam or a cut-open condom that makes a square—between your mouth and the vagina. A latex barrier reduces the risk of blood or vaginal fluids entering your mouth. Plastic food wrap also can be used as a barrier.