Share

Share

Share on FacebookShare on Facebook TweetShare on Twitter Share on WhatsAppShare on WhatsApp

SUBSCRIBE TO THE NEWSLETTER

BUENOS AIRES, Argentina. Talking about oral sex and HIV means, first and foremost, debunking a series of myths related to modes of transmission, potential risks, and methods of prevention, not only for this but also for other sexually transmitted infections (STIs). Studies show that the possibility of contracting HIV through oral sex is very low, but it is not zero, so it is essential to minimize any risk. 

The work of scientists and health researchers in recent years has resulted in a key concept for approaching information and prevention: “undetectable=untransmittable” or U=U . This concept implies that when a person with HIV on treatment maintains an undetectable viral load for at least six months (this is the criterion in certain guidelines for confirming sustained viral suppression), there is no possibility of sexual transmission of the virus, which is further reduced in the case of oral sex. However, questions remain about whether it is actually possible to transmit the virus through this practice. 

Does oral sex transmit HIV?

Natalia Laufer is an infectious disease physician, researcher, and professor of Immunology and Infectious Diseases. She is also a researcher at the National Scientific and Technical Research Council (CONICET), an infectious disease physician at the Dr. Juan A. Fernández General Hospital in Buenos Aires, and secretary of the Hepatitis Committee of the Argentine Society of Infectious Diseases (SADI).

She is also, along with Lorena Abusamra, Leonel Cruces, María José Rolón, and Alicia Sisto, one of the authors of the study “Undetectable = Untransmittable, are we communicating the message correctly?” which was presented in October 2024 at the international HIV conference in Glasgow. In it, they analyze the scope of information about HIV. 

He explains that while the risk of transmission is extremely low, it cannot be said to be completely zero: “To give an idea of ​​the risk of acquiring HIV through this route, we're talking about 0 to 4 infections per 10,000 contacts. As with any other transmission route, the risk is higher if there is ejaculation. For example, in receptive oral sex, because a greater amount of virus is potentially exposed. And it's higher if there are ulcers or lesions in the oral mucosa, because that also allows for greater ease in penetrating the mucosa, which is the first barrier—that is, the mucous membrane or the skin.”. 

Dr. Iael Altclas, an infectious disease specialist at CEMAR 3, a GCBA center affiliated with Pirovano Hospital, adds that oral sex “is not considered a high-risk sexual practice, even if barrier methods like condoms are not used. In recent years, guidelines regarding post-exposure prophylaxis for HIV have changed. Previously, it was said that if oral sex involved ejaculation, this intervention was indicated, but that is no longer the case. The reality is that the risk of HIV transmission through oral sex is very low, and it is practically impossible to transmit the virus that way.”

What increases the risk of contracting HIV through oral sex

Regarding the increased risk, Iael Altclas, a physician specializing in sexual diversity, explains: “If someone has a lesion in the genital area, and if the skin is broken and there is suddenly a discharge of fluids or blood; or if the skin barrier is interrupted and that comes into contact with the mucous membrane of the mouth, there could be some degree of transmission, but many conditions have to be met. Acquiring the HIV virus is not so simple. Specifically, in oral sex, there has to be visibly broken skin, with bleeding and so on.” 

According to both specialists, unprotected oral sex is riskier in the case of other sexually transmitted infections (STIs). “The risk is much higher; in fact, a significant percentage of people who have rectal or urethral gonorrhea also have it in their throat. Similarly, many syphilis lesions can appear on the oral mucosa, which increases the risk,” Laufer explains. 

How to prevent STIs

The safe way to practice oral sex is with the use of a condom. “It is essential to consider that oral sex can be associated with acquiring, for example, hepatitis A because it is an infection transmitted through the anus. Using these latex barriers prevents the acquisition of HIV or other STIs,” says Laufer.

There's a saying that oral sex is safe. "It's a myth that needs to be debunked," Laufer explains. "We need to look beyond HIV and consider all the other STIs, such as HPV. There's an increase in HPV-related cancers of the oral mucosa and pharynx due to unprotected sex. And then there are other sexually transmitted infections like syphilis, gonorrhea, and hepatitis in this context."

Of the sexually transmitted infections (STIs), HIV has the lowest risk of transmission through oral sex. However, experts are now pointing out the worrying increase in other preventable infections. 

“There is a low risk of HIV transmission through oral sex, but there are other diseases like syphilis, chlamydia, gonorrhea, MPOX, and monkeypox. For the first three, the traditional prevention method is the vaginal or penile condom. And new prevention strategies, such as doxycycline, which involves taking 200 milligrams of doxycycline within 24 to 72 hours ofunprotected sex. This is especially effective against syphilis, chlamydia, and gonorrhea,” explains Dr. Iael Altclas. “Doxycycline is effective at preventing approximately 70 to 80% of the risk of acquiring syphilis and chlamydia. The percentages are slightly lower in studies for gonorrhea, around 30%.”

Other preventative measures include vaccination against hepatitis A or B, and HPV. A vaccine against MPOX (Mpox) also exists, but it has not yet arrived in Argentina. 

Where to find information 

Both specialists recommended getting information through the CDC website,  or the STI and HIV Directorate of the City of Buenos Aires, Mayo Clinic and academic institutions that research and generate reliable information. 

This note is supported by the IAS (International AIDS Society) through the Community Project Grants, as part of the preparations for the AIDS Conference 2026.