Yes — you can get a sexually transmitted infection (STI) from oral sex. Several common infections, including gonorrhea, herpes, syphilis, chlamydia, and HPV, can pass between the mouth, throat, and genitals through oral contact. The risk is often lower than with vaginal or anal sex, but it is real, and many infections cause no obvious symptoms.
How oral sex transmits STIs
STIs spread when an infectious organism — a bacterium, virus, or parasite — passes from one person's body to another. During oral sex, that contact happens between the mouth or throat and a partner's genitals or anus. Infections can travel in either direction: from the genitals to the mouth, or from an infected mouth or throat to the genitals.
Some STIs spread through bodily fluids such as semen, vaginal fluid, or blood. Others spread through skin-to-skin contact, which means a barrier does not always fully cover the area where transmission can occur. This is why no single prevention step removes all risk, but layering protections makes a meaningful difference.
Which STIs can spread through oral sex?
According to the CDC, several infections — including chlamydia, gonorrhea, syphilis, herpes, HPV, and HIV — can be passed on through oral sex.
Gonorrhea and chlamydia
Both of these bacterial infections can settle in the throat as well as the genitals. Throat infections are frequently silent. As the NHS notes, gonorrhea can pass from person to person through vaginal, anal, or oral sex without a condom, and not everyone develops symptoms. You can learn more in our guides to gonorrhea and chlamydia.
Herpes (HSV-1 and HSV-2)
Herpes spreads through skin-to-skin contact, including contact with cold sores around the mouth. Oral sex can transfer the virus from the mouth to the genitals or vice versa. The virus can pass even when no sores are visible. See our genital herpes article for more.
Syphilis
Syphilis can be passed through direct contact with a syphilis sore, which may form on the lips, mouth, genitals, or anus. Because early sores can be painless and easy to miss, transmission during oral sex is well documented.
HPV (human papillomavirus)
HPV spreads through skin-to-skin contact and can infect the mouth and throat. Certain high-risk types are linked to throat (oropharyngeal) cancers. Vaccination is a key prevention tool — read our HPV explainer for details.
HIV
The risk of HIV from oral sex is very low compared with other types of sex. Risk can increase in the presence of mouth ulcers, bleeding gums, or other untreated STIs. If you are concerned about HIV exposure, a healthcare provider can talk you through prevention options and testing.
Symptoms to watch for
A crucial point: many oral and throat STIs cause no symptoms at all, which is exactly why they spread. The CDC emphasizes that gonorrhea often has no symptoms even while it can cause serious health problems and be passed on.
When symptoms do appear, they may include:
- A sore throat that does not go away
- Redness or trouble swallowing
- Swollen glands in the neck
- Sores, blisters, or ulcers on the lips, mouth, or genitals
- Unusual genital discharge or burning
Because symptoms are unreliable, you cannot tell from how you feel whether you have an infection. If you notice any of these, or if a partner tests positive, speak with a healthcare provider.
How to lower your risk
You can support your sexual health while reducing your STI risk. Evidence-based steps include:
- Use a barrier. A condom or a dental dam (a thin square of latex) reduces contact during oral sex.
- Get tested regularly. Routine screening catches silent infections early. See our STI testing guide for what to expect.
- Treat infections promptly. Untreated STIs raise the risk of passing on or acquiring others.
- Consider HPV vaccination. It protects against the HPV types most linked to cancer.
- Avoid oral contact when sores are present, and talk openly with partners about testing.
The NHS and CDC both stress that using condoms or other barriers and getting tested are the most reliable ways to reduce STI risk — including during oral sex, where many infections have no symptoms. For a broader overview, see our guide on how to prevent STIs.
The bottom line
So, can you get an STI from oral sex? Yes. Gonorrhea, chlamydia, syphilis, herpes, and HPV can all spread through oral contact, and HIV can in rare cases. Because throat and oral infections so often cause no symptoms, regular testing matters as much as barriers do. Combine barriers, routine screening, prompt treatment, and HPV vaccination — and explore the rest of our STIs and testing library to stay informed. For individual concerns, always consult a qualified healthcare provider.
