December 2000

Preventing the Sexual Transmission of HIV,

the Virus that Causes AIDS

What You Should Know about Oral Sex

Oral Sex Is Not Considered Safe Sex

Like all sexual activity, oral sex carries some risk, particularly when one partner or the other is known to be

infected with HIV, when either partner’s HIV status is not known, and/or when one or the other partner is not

monogamous or injects drugs. Numerous studies have demonstrated that oral sex can result in the

transmission of HIV and other sexually transmitted diseases (STDs). Abstaining from oral, anal, and

vaginal sex all together or having sex only with a mutually monogamous, uninfected partner are the only ways that

individuals can be completely protected from the sexual transmission of HIV. 

Oral Sex is a Common Practice

Oral sex involves giving or receiving oral stimulation (i.e. sucking or licking) to the penis, the vagina, and/or the

anus. Fellatio is the technical term used to describe oral contact with the penis. Cunnilingus is the technical term

which describes oral-vaginal sex. Anilingus (sometimes called “rimming”) refers to oral-anal contact. Studies

indicate that oral sex is commonly practiced by sexually active male-female and same-gender couples of various

ages, including adolescents. Although there are only limited national data about how often adolescents engage in

oral sex, some data suggest that many adolescents who engage in oral sex do not consider it to be sex; therefore

they may use oral sex as an option to experience sex while still, in their minds, remaining abstinent. Moreover,

many consider oral sex to be a safe or no risk sexual practice. In a recent national survey of teens conducted for

The Kaiser Family Foundation, 26% of sexually active 15 to 17 year olds surveyedresponded that one “cannot

become infected with HIV by having unprotected oral sex”, and an additional 15% didn’t know whether or not

one could become infected in that manner.

Oral Sex and the Risk of HIV Transmission

The risk of HIV transmission from an infected partner through oral sex is much smaller than the risk of HIV

transmission from anal or vaginal sex. Because of this, measuring the exact risk of HIV transmission as a result

of oral sex is very difficult. In addition, since most sexually active individuals practice oral sex in addition to other

forms of sex, such as vaginal and/or anal sex, when transmission occurs, it is difficult to determine whether or not

it occurred as a result of oral sex or other more risky sexual activities. Finally, several co-factors can increase the

risk of HIV transmission through oral sex, including: oral ulcers, bleeding gums, genital sores, and the presence of

other STDs.

When scientists describe the risk of transmitting an infectious disease, like HIV, the term “theoretical risk” is

often used. Very simply, “theoretical risk” means that passing an infection from one person to another is

possible, even though there may not yet be any actual documented cases. “Theoretical risk” is not the same as

likelihood. In other words, stating that HIV infection is “theoretically possible” does not necessarily mean it is

likely to happen—only that it might. Documented risk, on the other hand, is used to describe transmission that has

actually occurred, been investigated, and documented in the scientific literature.
Theoretical and Documented 

Risk of HIV Transmission During

Oral-Penile Contact

Theoretical and Documented Risk

of HIV Transmission During

Oral-Vaginal Contact

Theoretical and Documented Risk

of HIV Transmission During

Oral-Anal Contact

Theoretical:

In fellatio, there is a theoretical

risk of transmission for the

receptive partner (the person

who is sucking) because infected

pre-ejaculate ("pre-cum") fluid or

semen can get into the mouth. 

For the insertive partner (the

person who is being sucked),

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.

Theoretical:

Cunnilingus carries a theoretical

risk of HIV transmission for the

insertive partner (the person who

is licking or sucking the vaginal

area) because infected vaginal

fluids and blood can get into the

mouth. (This includes, but is not

limited to, menstrual blood). 

Likewise, there is a theoretical

risk of HIV transmission during 

cunnilingus for the receptive

partner (the person who is

having her vagina licked or

sucked) if infected blood from

oral sores or bleeding gums

comes in contact with vulvar or

vaginal cuts or sores.

Theoretical:

Anilingus carries a theoretical

risk of transmission for the

insertive partner (the person who

is licking or sucking the anus) if

there is exposure to infected

blood, either through bloody

fecal matter (bodily waste) or

cuts/sores in the anal area. 

Anilingus carries a theoretical

risk to the receptive partner (the

person who is being

licked/sucked) if infected blood

in saliva comes in contact with

anal/rectal lining.

Documented: 

Although the risk is many times

smaller than anal or vaginal sex,

HIV has been transmitted to

receptive partners through

fellatio, even in cases when

insertive partners didn't

ejaculate ("cum").

Documented: 

The risk of HIV transmission

during cunnilingus is extremely

low compared to vaginal and

anal sex. However, there have

been a few cases of HIV

transmission most likely

resulting from oral-vaginal sex. 

Documented:

There has been one published

case of HIV transmission

associated with oral-anal sexual

contact. 

Other STDs Can Also Be Transmitted From Oral Sex

Scientists have documented a number of other sexually transmitted diseases that have also been transmitted

through oral sex. Herpes, syphilis, gonorrhea, genital warts (HPV), intestinal parasites (amebiasis), and hepatitis

A are examples of STDs which can be transmitted during oral sex with an infected partner.

For more information see Oral Sex and STDs Fact Sheet.

Reducing the Risk of HIV Transmission Through Oral Sex

The consequences of HIV infection are life-long, life-threatening, and extremely serious. You can lower any

already low risk of getting HIV from oral sex by using latex condoms each and every time. For cunnilingus or

anilingus, plastic food wrap, a condom cut open, or a dental dam can serve as a physical barrier to prevent

transmission of HIV and many other STDs. Because anal and vaginal sex are much riskier and because most

individuals who engage in unprotected (i.e. without a condom) oral sex also engage in unprotected anal and/or

vaginal sex, the exact proportion of HIV infections attributable to oral sex alone is unknown, but is likely to be

very small. This has led some people to believe that oral sex is completely safe. It is not.