Of the different sex acts, the one that often causes the greatest amount of confusion in terms of risk—and raises the greatest number of questions—is oral-penile. The fact is, most experts agree that fellatio, often referred to as "blow jobs," is not an efficient route of HIV transmission. However, this does not mean that it can't happen.
Because unprotected fellatio can mean that body fluids from one person can (and do) come into contact with the mucosal tissues or open cuts, sores or breaks in the skin of another person, there is a "theoretical risk" of HIV transmission. "Theoretical risk" means that passing an infection from one person to another is considered possible, even though there haven't been any (or have only been a few) documented cases. This term is used to differentiate from documented risks. Being the receptive partner during unprotected anal or vaginal intercourse with an HIV-positive person is a documented risk, as has been proven with numerous studies and case examples. Unprotected oral sex is a theoretical risk, as it is considered possible, but has never been shown to be an independent risk factor for HIV infection.
There have been three case reports and a few studies suggesting that some people have been infected with HIV as a result of unprotected oral sex. However, these case reports and studies all involved men who were the receptive partners (the person doing the "sucking") during unprotected oral sex with another HIV-positive man. There haven't been any case reports or studies documenting HIV infection among female receptive partners during unprotected oral sex. Even more importantly, there hasn't been a single documented case of HIV transmission to an insertive partner (the person being "sucked") during unprotected oral sex, either among MSM, or heterosexuals.
Is insertive oral sex a possible route of HIV transmission? Yes. But is it a documented risk? No.
To reduce the risk:
- Don't get cum in your mouth. Also consider using an unlubricated (possibly flavored) condom every time you have oral sex with a partner who is positive or whose HIV status you do not know.
- Avoid brushing or flossing your teeth immediately before oral sex. This reduces the risk of cuts, tears or abrasions in the mouth that can serve as an entry way for HIV.
