Oral sex without any protection can be dangerous.
Oral sex is sex that involves the mouth and the penis, vagina, or anus (butt hole). Some other words for different kinds of oral sex are "blow job," "giving head," "going down on," "eating out," "sucking," "cunnilingus," or "rimming."
Giving oral sex (blow job) to a man has been proven to carry some risk of getting HIV, although most scientists believe the risk is relatively low. The risk increases if the person giving the blow job has any cuts or scrapes in his or her mouth, even small ones that can be caused by brushing or flossing right before sex. To have safer oral sex, avoid getting any semen in your mouth, either by stopping oral sex before ejaculation or by using a nonspermicidal condom. You can use an oral barrier such as a dental dam or plastic wrap to make oral-anal sex (rimming) safer.
Giving oral sex to (going down on) a woman is also relatively low risk. The possibility of infection is higher if there is menstrual blood, if the woman has another STD in addition to HIV, or if the person performing oral sex has sores or cuts in the mouth. You can use an oral barrier such as a dental dam orplastic wrap to make oral-vaginal sex (cunnilingus) or oral-anal sex (rimming) safer.
The risk of other sexually transmitted diseases
There are many diseases besides HIV that can be passed through unprotected oral sex, including herpes, syphilis, gonorrhea, hepatitis A, and the viruses that cause warts, intestinal parasites, and other conditions