Oral sex is the use of the mouth, lips, or tongue to stimulate a partner’s genitals or genital area. It is one of the most common sexual activities among adults and can be performed on or by people of any gender. While many people think of it as lower risk than intercourse, oral sex can still transmit infections, and understanding those risks helps you make informed choices.
Types of Oral Sex
There are three main types, each defined by which body part is being stimulated. Fellatio is oral contact with the penis. Cunnilingus is oral contact with the vagina and surrounding area. Anilingus (sometimes called rimming) is oral contact with the anus.
Any of these can involve kissing, licking, or sucking, and all carry their own set of health considerations depending on what fluids or skin-to-skin contact is involved.
Can Oral Sex Transmit STIs?
Yes. Oral sex carries a lower risk of sexually transmitted infections than vaginal or anal intercourse, but it is not risk-free. Several infections spread through oral contact with the genitals or anus.
Herpes (HSV-1 and HSV-2) is one of the most easily transmitted infections during oral sex. A cold sore on the mouth can spread herpes to a partner’s genitals, and genital herpes can spread to the mouth. Transmission can happen even when no visible sore is present.
Gonorrhea can infect the throat through fellatio, creating what’s known as pharyngeal gonorrhea. This throat infection often causes no symptoms, which means people can unknowingly pass it to a partner’s genitals during future oral contact. Syphilis and chlamydia can also be transmitted orally, though chlamydia of the throat is less common.
HIV transmission through oral sex is considered low risk. A CDC systematic review categorized the per-act risk from oral sex as the lowest among sexual exposures, compared to receptive anal intercourse, which had the highest rate at about 138 infections per 10,000 exposures. The risk increases if there are open sores, bleeding gums, or contact with blood.
The HPV and Throat Cancer Connection
Human papillomavirus (HPV) deserves its own discussion because the link between oral sex and certain cancers is significant. HPV is transmitted to the mouth primarily through oral sex, and about 10% of men and 3.6% of women carry an oral HPV infection. The rates increase with age.
HPV is now thought to cause 60% to 70% of oropharyngeal cancers in the United States. These are cancers that develop in the back of the throat, the base of the tongue, and the tonsils. The timeline is long: it typically takes years, sometimes decades, after initial HPV infection for these cancers to develop. HPV vaccination, which is recommended for preteens but available for adults up to age 45, protects against the strains most likely to cause cancer.
Can Oral Sex Cause Pregnancy?
No. Oral sex on its own cannot cause pregnancy. For conception to occur, sperm must reach the inside of the vagina and travel to an egg. Swallowing or having semen in the mouth does not create a path to the reproductive tract.
This is a surprisingly common concern. Researchers who analyzed emails sent to a reproductive health website found that many people believed sperm could somehow travel from the mouth to the vagina, or that pre-ejaculatory fluid contained enough sperm to cause pregnancy through indirect contact. Three small studies have found no motile sperm in pre-ejaculatory fluid. The widespread belief that it does likely traces back to a 1966 Masters and Johnson textbook claim that was never evidence-based.
The only scenario where pregnancy could theoretically result is if semen came into direct contact with the vaginal opening shortly after oral sex, for example through touch. Even then, the probability is extremely low.
Reducing Risk With Barriers
Barrier methods can significantly reduce the chance of infection during oral sex. For fellatio, an unlubricated latex or polyurethane condom placed over the penis works as a barrier between the mouth and skin. Flavored condoms are specifically designed for this purpose.
For cunnilingus and anilingus, the recommended barrier is a dental dam, a thin sheet of latex or polyurethane placed over the vaginal opening or anus. Use a new dam each time, apply it before oral contact begins, and keep it in place until you’re finished. Water-based or silicone-based lubricant on the side touching skin helps prevent tearing.
A few important details: never reuse a dental dam, don’t stretch it (stretching weakens the material), and avoid oil-based products like petroleum jelly, lotion, or cooking oil, which break down latex. If you don’t have a dental dam, you can make one by cutting the tip and base off an unrolled latex condom, then cutting down one side to create a flat sheet.
Hygiene and Practical Considerations
Good oral hygiene matters more than people realize. Brushing or flossing right before oral sex can actually increase risk by creating tiny cuts in the gums that give infections an entry point. If you want to freshen up, rinsing with mouthwash or water is a gentler option.
For anilingus specifically, the main hygiene concern is the transfer of intestinal bacteria. Washing the area beforehand with warm water and mild soap reduces this risk. Avoid moving from anal to vaginal contact without cleaning or changing barriers, as this can introduce bacteria that cause vaginal infections or urinary tract infections.
If either partner has visible sores, cuts, or active cold sores, avoiding oral sex until they heal is the most effective way to prevent transmission of herpes, syphilis, and other infections that spread through broken skin.