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It’s well-known that HIV can be contracted through vaginal or anal sex as well as through sharing drug injection equipment. However, there’s also a risk of contracting it via oral sex, just like with other sexually transmitted infections (STIs) — albeit a smaller risk.

The virus is transmitted between people when the fluids of one person come into contact with the bloodstream of another. This contact can occur from a cut or broken skin, or through the tissues of the vagina, rectum, foreskin, or the opening of the penis.

6 bodily fluids that can transmit HIV
  • blood
  • semen
  • pre-ejaculatory fluid (“pre-cum”)
  • breast milk
  • rectal fluid
  • vaginal fluid

Certain factors can increase the risk of HIV being transmitted through oral sex. Read on to find out what they are and how you can help prevent transmission.

According to HIV.gov, oral sex has a low risk of transmitting HIV. While estimates of HIV transmission during oral sex are low, they aren’t zero.

There are few studies in this area, making it difficult to give a precise risk level. There’s also only a risk if the person with HIV has a detectable viral load.

Why is it difficult to get data?

It can be hard to know where transmission occurred, as people who engage in oral sex also tend to engage in vaginal or anal sex. Plus, securing data requires asking people to give detailed information about their sex lives.

Fellatio (oral-penile sex) carries some risk:

  • If you’re giving a blowjob. Receptive oral sex with a person who was assigned male at birth (AMAB) and has HIV does have a potential risk, if only a low one. The risk is higher if pre-cum or semen from an HIV-positive person enters the mouth of another.
  • If you’re receiving a blowjob. Insertive oral sex has a much lower risk of transmission. Enzymes in the saliva can be protective in that they neutralize many viral particles. In fact, infection is only likely to be possible if the person giving oral sex is bleeding from the gums, a cut, or an ulcer in their mouth and is HIV-positive.

There are no documented cases of HIV being transmitted between partners through cunnilingus (oral-vaginal sex). But if a person receiving cunnilingus is menstruating and HIV-positive, there’s a potential chance of transmission.

Similarly, anilingus (oral-anal sex), or “rimming,” is said to have a very low risk of transmission.

These factors can increase the risk of HIV transmission through oral sex:

  • Status. Risk varies based on whether the person who is HIV-positive is giving or receiving oral sex. If the HIV-positive person is receiving oral sex, the person giving it may have a higher risk.
  • Viral load. There’s a larger risk of contracting HIV if the HIV-positive person has a high viral load, which increases infectivity. If the viral load is undetectable, there’s a much lower chance of transmitting the virus.
  • Ejaculation. During oral sex, ejaculation may increase the risk of transmission.
  • Cuts, sores, or ulcers. Openings in the mouth, vagina, anus, or on the penis are possible routes for HIV transmission — for example, if a person’s gums bleed after they brush their teeth or if they have lesions in their mouth as a result of another condition. HIV-related infections, like candidiasis, can cause sores that affect the integrity of the tissue in the mouth.
  • Menstruation. HIV levels can be higher in vaginal fluid when a person is menstruating. Coming into contact with menstrual blood with the mouth may then increase contraction risk.
  • STIs. Having an STI can increase the risk of developing HIV, especially if the STI causes sores or inflammation that damage skin and make it easier for HIV to enter.

As there is some evidence that HIV can be transmitted through oral sex, it’s best to take measures to reduce the risk of transmission.

If you’re HIV-positive

An undetectable viral load makes transmission nearly impossible. This is often achievable via antiretroviral therapy (ART).

ART reduces the risk of HIV transmission by up to 96 percent in mixed-status couples.

Most people receiving proper treatment have an undetectable viral load within 6 months. If it remains undetectable for at least 6 months, the virus is unable to be transmitted through sex.

If a partner is taking ART but the infection is not yet virally suppressed, it’s important to use a barrier method, like condoms, to help reduce the risk of transmission between partners.

If you’re HIV-negative

If you don’t have HIV but a sexual partner does, consider using pre-exposure prophylaxis (PrEP), a daily pill that stops the virus from replicating and helps prevent transmission.

If you have unprotected sex with an HIV-positive partner or someone whose status is unknown, you can use post-exposure prophylaxis (PEP) to significantly reduce the risk of transmission.

PEP must be started within 72 hours of exposure to the virus in order to be effective.

Giving and receiving oral sex

Semen and pre-cum can transmit HIV. While avoiding ejaculating into the mouth may help reduce the risk, there’s still a chance that pre-ejaculatory fluid may enter the mouth. Therefore, using a barrier method is a more reliable way to prevent transmission.

Condoms and dental dams can be used during every oral sex act. Change to a new one if you move from the vagina or penis to the anus, or vice versa. You can also use lubricants to prevent friction or tearing and further reduce exposure risk.

Abstain from oral sex if you have any cuts, abrasions, or sores in your mouth. Any opening in the skin is an avenue for possible viral exposure.

Finally, be careful not to cut or tear your partner’s skin with your teeth during oral sex.

Other strategies

One of the best ways to prepare yourself or your partner for sex is to disclose your status. If you don’t know yours, get tested for HIV and other STIs to find out. Test again if you have a new sexual partner.

Empowered with this information, you can make appropriate protection and medication choices.

Good dental health can also offer some protection. Properly caring for your gums and the tissues in your mouth may prevent bleeding and other oral infections, reducing your risk for contracting HIV.

While there’s less chance of contracting HIV through oral sex, there’s still a risk. This can be increased by the likes of cuts and sores or by allowing pre-ejaculatory fluid or semen to enter the mouth.

Help protect yourself and any sexual partners by getting tested, sharing your status, and using barrier methods and prescribed treatment appropriately.

Read this article in Spanish.


Lauren Sharkey is a U.K.-based journalist and author specializing in women’s issues. When she isn’t trying to discover a way to banish migraines, she can be found uncovering the answers to your lurking health questions. She has also written a book profiling young female activists across the globe and is currently building a community of such resisters. Catch her on Twitter.