What Is the Risk of HIV from Oral Sex?

Separating Facts From Common Misconceptions

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It’s possible to get HIV from oral sex, but it’s not the most likely way to contract the virus. For the most part, oral sex—which includes fellatio (oral-penile), cunnilingus (oral-vaginal), or anilingus (oral-anal)—is not an efficient route of HIV (human immunodeficiency virus) transmission compared to penetrative intercourse (particularly anal sex).

This article will discuss the risk factors for getting HIV from oral sex and ways to lower your risk and protect yourself and your partners. 

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Theoretical vs. Documented Risk of HIV From Oral Sex

There is an important difference in the theoretical and documented risk of getting HIV from oral sex. 

A reported change is based on the actual number of cases in which HIV can be directly attributed to an act of oral sex. The risk of infection by oral sex is not zero, but it’s extremely low.

In fact, according to research from the University of California at San Francisco's Centers for AIDS Prevention Studies, the probability of HIV infection through unprotected oral sex is statistically zero. However, the researchers explained that they “cannot rule out the possibility that the probability of infection is greater than zero."

The lower risk from oral sex has to do with substances in saliva that block HIV's ability to cause infection. Saliva kills HIV-infected white blood cells that HIV targets (CD4 T-cells). There are also specific proteins like mucin 1 (MUC1) and salivary agglutinin (SAG) that can render the virus non-infectious.

Certain factors and situations can raise your personal risk—sometimes by a lot. For example, the risk of transmission is increased if you have mouth ulcers, bleeding gums, genital sores, or the having another sexually transmitted infection (STI).

Understanding and identifying these factors can help you can make informed, safer choices about sex that will protect you and your partners. 

Risk of HIV by Type of Oral Sex

The chance that you’ll transmit or contract HIV through oral sex depends a lot on the contact you’re having with another person. Putting aside all other risk factors, the potential for infection varies based on whether the non-infected person is giving or receiving oral sex.

The risk of HIV from oral sex is anywhere from 0%–1%, according to research from the London School of Hygiene and Tropical Medicine.

While these figures suggest that the risk of getting HIV from oral sex acts is low from a population perspective, that does not mean it’s low from an individual perspective. 

The more risk factors you have, the greater the risk of transmission will be. The risk numbers change if you factor in specific sexual behaviors:

  • Receptive fellatio, meaning that the non-infected person performs oral sex on a male partner with HIV, is considered a shallow risk. Among men who have sex with men (MSM), the risk per act is around 0.04%.
  • Insertive fellatio (mouth-to-penis contact) is even less likely to transmit HIV because the enzymes in saliva can neutralize the viral particles.
  • Cunnilingus (mouth-to-female genitalia contact) is not likely to transmit HIV.
  • Anilingus (mouth-to-anus contact) is considered low risk, especially for the partner who is receiving it.

Additional Risk Factors for HIV From Oral Sex

An infected partner's HIV viral load is the biggest factor in determining the likelihood of infection. The higher the HIV viral load, the more likely a person is to spread the virus to others. An undetectable viral load carries an extremely low risk of spreading HIV.

Several other factors also affect risk: 

  • Ejaculation during oral sex is thought to be riskier than oral sex without ejaculation, but there is no evidence that ejaculation is the only factor for infection.
  • Cuts, abrasions, or sores in a person’s mouth can offer a potential way for the virus to get into the body. Maintaining good dental health can lower the chances of bleeding gum disease and other oral infections that can raise the risk of HIV spread.
  • Certain sexually transmitted infections (STIs), like syphilis and gonorrhea, do not always have symptoms (asymptomatic). Therefore, these conditions often go unnoticed, particularly if they are in the throat, vagina, or rectum.
  • Lesions or sores from HIV-related infections like candidiasis or herpes simplex can also make the mucus membranes in the mouth and throat weaker. Taking HIV therapy can lower the risk of these infections.
  • The concentration of HIV in vaginal fluids can increase during menstruation because HIV-bearing cells are shed from the cervix. This can also happen if a person with a penis gets urethritis. Acute inflammation can increase viral shedding even in persons with an otherwise undetectable viral load.

How to Minimize Risk of HIV

The most important thing you can do is to avoid sexual activity when you’re in a “high risk” time, like during a herpes outbreak. At lower-risk times, the best way to minimize the risk of infection is to practice safer sex.

If you have multiple sex partners or are unsure about the health of a sex partner, safe sex is even more important. Using condoms and dental dams when you’re engaging in cunnilingus or anilingus will protect you and your partner.

It’s also recommended that you avoid brushing or flossing your teeth right before giving oral sex because it could make your gums bleed, which makes HIV transmission more of a risk. 

There are additional strategies that can further reduce risk:

  • If you are HIV-positive, take your HIV medicine as prescribed by your healthcare provider. If your viral load stays undetectable, you have no risk of sexually transmitting HIV to HIV-negative partners.
  • If you are HIV-negative, you can ask your provider to prescribe HIV pre-exposure prophylaxis (PrEP)—a type of therapy that comes in the form of a daily pill or an injection every two months. It can reduce your risk of infection by more than 90%.
  • Regular HIV screening is recommended for persons at high risk of infection, including MSM, injecting drug users, and persons with multiple sex partners. Periodic STI screenings are also recommended.

Communication with your partners is also important to avoid HIV. Whether you are HIV-positive or HIV-negative, learning how to discuss safe sex and how to disclose your HIV status is important. 

Summary

The risk of getting HIV from oral sex is low, but it’s still possible. Practicing safe sex, communicating with partners, understanding your risk, and taking steps to reduce your risk are steps you can take to protect yourself and your partners from HIV. 

12 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By James Myhre & Dennis Sifris, MD
Dennis Sifris, MD, is an HIV specialist and Medical Director of LifeSense Disease Management. James Myhre is an American journalist and HIV educator.