Oral Sex and the Risk of HIV

Separating Documented Risk From Theoretical Risk

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There is a commonly held belief among many people that oral sex poses little or no risk of HIV. But the truth is that, like any other sexual activity, oral sex carries a potential of transmitting HIV and other sexually transmitted infections. The risk is even greater in mixed-status (serodiscordant) couples, people who have multiple sex partners, or in those who share needles.

Truth be told, abstaining from sex may be the only way to completely avoid the sexual transmission of HIV, but how realistic is that?

Documented vs. Theoretical Risks of Oral Sex

In epidemiological terms, risk is classified as either being documented (where transmission which has been measured and recorded in the scientific literature) or theoretical (where transmission is possible, however unlikely).

While there has been documented risk of HIV by oral sex, the number is incredibly small, almost to the point of being negligible. This simple fact is that it is hard to calculate the actual risk with oral sex, in part because most people who do so also engage in other forms of sex, as well, including vaginal or anal sex.

Moreover, oral sex is comprised of different activities (oral-penile, oral-vaginal, oral-anal), different roles (receptive, insertive), and changes of role (receptive to insertive and vice versa), further muddling how much actual risk each activity represents.

Oral-Penile (Fellatio)

  • Theoretical Risk: With fellatio, there is a theoretical risk of transmission for the receptive partner because infected pre-ejaculate fluid ("pre-cum") or semen can both get into the mouth. For the insertive partner there is a theoretical risk of infection because infected blood from a partner's bleeding gums or an open sore could come in contact with a scratch, cut, or sore on the penis.
  • Documented Risk: Although the risk is many times less than anal or vaginal sex, there have been cases where HIV has been transmitted to the receptive partner through fellatio and even when insertive partners didn't ejaculate.

Oral-Vaginal (Cunnilingus)

  • Theoretical Risk: Cunnilingus carries a theoretical risk of HIV transmission for the insertive partner (the person licking the vaginal area) because infected vaginal fluids and blood can get into the mouth. Likewise, there is a theoretical risk of transmission for the receptive partner (the person being licked) if infected blood from oral sores or bleeding gums comes in contact with vaginal cuts or sores.
  • Documented Risk: Again, the risk of HIV transmission from cunnilingus is extremely low compared to vaginal and anal sex. However, there have been a spattering cases in which HIV transmission most likely resulted from oral-vaginal sex.

Oral-Anal (Anilingus)

  • Theoretical Risk: Anilingus carries a theoretical risk of transmission for the insertive partner (the person licking the anus) if there is exposure to infected blood, either through cuts or sore in the anus or rectum. Anilingus carries a theoretical risk to the receptive partner (the person who is being licked) if infected blood in saliva comes in contact with anal/rectal cuts or tears.
  • Documented Risk: To date, there has been only one published case of HIV transmission associated with oral-anal contact. As such, anilingus is considered one of the most unlikely means of HIV transmission.
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Article Sources

  • Boily, M.; Baggaley, R.; Wang, L.; et al. "Heterosexual risk of HIV-1 infection per sexual act: Systematic review and meta-analysis of observational studies." Lancet Infectious Diseases. February 2009; 9(2):118-129.
  • Dosekun, O. and Fox, J. "An overview of the relative risks of different sexual behaviours on HIV transmission." Current Opinions in HIV and AIDS, July 2010; 5(4): 291-297.
  • Page-Schafer, K.; Shiboski, C.; Osmond, D.; et al. "Risk of HIV infection attributable to oral sex among men who have sex with men and in the population of men who have sex with men." AIDS. November 22, 2012; 16(7):2350-2352.