Oral sex carries a lower risk of sexually transmitted infections than vaginal or anal sex, but it is not risk-free. At least six common STIs can pass between partners during oral contact, including gonorrhea, syphilis, chlamydia, herpes, HPV, and HIV. The level of risk depends on the specific infection, whether you’re giving or receiving, and a few practical factors you can control.
Which STIs Spread Through Oral Sex
The infections most commonly transmitted during oral sex are gonorrhea, syphilis, herpes, and HPV. Chlamydia and HIV can also spread this way, though less efficiently.
Gonorrhea is one of the easiest STIs to catch in the throat. You can pick it up by performing oral sex on a partner with a genital infection, and you can pass a throat infection to a partner’s genitals just as easily. Throat gonorrhea often causes no symptoms at all, which means many people carry and spread it without knowing. Having gonorrhea or chlamydia in the throat may actually make it easier to transmit those infections to future partners through oral sex.
Syphilis spreads through direct contact with a syphilis sore, which can appear on the genitals, anus, or mouth. If your mouth touches a sore during oral sex, the infection can take hold. Syphilis acquired orally can then spread throughout the body just as it would from any other route of transmission.
Herpes is extremely common and passes easily during oral sex. Most people with oral herpes (typically HSV-1) contracted it during childhood through non-sexual contact, but it can spread from the mouth to a partner’s genitals during oral sex. This is now one of the leading causes of new genital herpes cases. The virus can shed and transmit even when no visible cold sore is present.
HPV and the Cancer Connection
HPV deserves special attention because the long-term consequences go beyond a manageable infection. The virus spreads readily through oral sex, and about 10% of men and 3.6% of women carry oral HPV at any given time. Most oral HPV infections clear on their own within a year or two, but the ones that persist can cause serious problems.
HPV is thought to cause 60% to 70% of oropharyngeal cancers (cancers of the back of the throat, base of the tongue, and tonsils) in the United States. These cancers have been rising sharply over the past two decades, particularly in men. The HPV vaccine, originally promoted for preventing cervical cancer, also protects against the strains responsible for most of these throat cancers. It’s most effective when given before someone becomes sexually active, but it’s approved for adults up to age 45.
HIV Risk During Oral Sex
HIV transmission through oral sex is possible but rare. The CDC classifies the risk as “extremely low to no risk,” making it far less likely than transmission through anal or vaginal sex. The mouth is not an efficient entry point for the virus, and saliva contains proteins that inhibit HIV.
That said, the risk increases if the person performing oral sex has open sores, bleeding gums, or cuts in their mouth, or if either partner has another active STI. An untreated STI can create inflammation and tiny breaks in tissue that give HIV an easier path into the bloodstream.
Who Faces More Risk: Giving or Receiving
The person performing oral sex (the “giver”) generally faces the higher risk. Their mouth and throat are directly exposed to genital secretions and to any sores, lesions, or viral shedding on the partner’s skin. This is the person more likely to end up with throat gonorrhea, oral herpes (if they didn’t already have it), or an oral HPV infection.
The person receiving oral sex isn’t off the hook, though. They can contract genital herpes from a partner’s cold sore, pick up gonorrhea or chlamydia on their genitals from a partner’s throat infection, and acquire syphilis if their skin contacts a sore in or near the partner’s mouth.
Oral-Anal Contact Adds Extra Risks
Oral-anal contact (rimming) carries all the STI risks above plus the possibility of intestinal infections. Bacteria and parasites that live in the digestive tract can transfer to a partner’s mouth through this type of contact, even when the area looks and feels clean. Hepatitis A is a well-known risk, along with various bacterial and parasitic gut infections. The same barrier methods that work for other forms of oral sex apply here.
Factors That Raise Your Risk
Several things make STI transmission during oral sex more likely. Poor oral health is a significant one. Bleeding gums, gum disease, mouth ulcers, and recent dental work all create openings in the tissue that make it easier for infections to enter or exit the body. For the same reason, brushing or flossing right before oral sex can cause micro-abrasions in the gums that increase vulnerability. If you want to freshen up beforehand, rinsing with mouthwash is a better option than brushing.
Having multiple sexual partners increases the odds of encountering someone with an active infection. Ejaculation in the mouth raises exposure to infected fluids. And if either partner already has an STI, the inflammation it causes can make acquiring a second infection more likely.
How to Reduce the Risk
Condoms and dental dams are the most straightforward way to lower your risk during oral sex. A condom works for mouth-to-penis contact, while a dental dam, a thin sheet of latex or polyurethane, provides a barrier during mouth-to-vagina or mouth-to-anus contact. Neither eliminates risk entirely, but both significantly reduce the exchange of fluids and skin-to-skin contact that drive transmission.
Realistically, many people don’t use barriers for oral sex. If that’s the case, there are still things worth doing. Getting tested regularly is important, especially because throat infections with gonorrhea and chlamydia rarely cause symptoms. Standard urine-based STI tests won’t catch a throat infection. You need a throat swab, and you have to specifically ask for one. The CDC recommends that men who have sex with men get screened at all sites of contact (throat, urethra, rectum) at least once a year, and every three to six months if they have multiple partners. For women and other groups, throat and rectal screening is recommended based on sexual behavior and exposure.
The HPV vaccine is one of the most impactful preventive steps you can take. Staying up to date on hepatitis A vaccination is also worthwhile, particularly if oral-anal contact is part of your sex life. Knowing your own STI status and your partner’s, avoiding oral sex when cold sores are visible, and keeping your mouth healthy all meaningfully lower the odds of transmission.