Bacterial vaginosis (vaginal inflammation caused by bacterial overgrowth) is easily spread from woman to woman, but HIV/AIDS is much less likely to be passed on this way, for example. If you’re a lesbian or bisexual woman who has had sex with men, you’re more at risk of the full range of STIs. Talk to your doctor about testing if you’re concerned you may be at risk.
Oral sex is commonly used as a means of preserving virginity, especially among heterosexual pairings; this is sometimes termed technical virginity (which additionally includes anal sex, mutual masturbation and other non-penetrative sex acts, but excludes penile-vaginal sex). The concept of "technical virginity" or sexual abstinence through oral sex is particularly popular among teenagers, including with regard to teenage girls who not only fellate their boyfriends to preserve their virginities, but also to create and maintain intimacy or to avoid pregnancy. Other reasons given for the practice among teenage girls are peer-group pressure and as their introduction to sexual activity. Additionally, gay males may regard fellatio as a way of maintaining their virginities, with penile-anal penetration defined as resulting in virginity loss, while other gay males may define fellatio as their main form of sexual activity.
Doctors used to think that human papillomavirus (HPV), the most common sexually transmitted infection in the United States, couldn’t affect the mouth. But recent research has them rethinking this notion. Scientists have now shown that the same high-risk strains of HPV that lead to cervical cancer can also be transmitted by oral sex and potentially cause head, neck, and throat cancer, as well.