Sexually transmitted infections and diseases (STIs) aren’t just contracted through vaginal or anal sex — any skin-to-skin contact with the genitals is enough to pass an STI on to your partner.

This means that oral sex using the mouth, lips, or tongue can pose similar risks as other sexual activities.

The only way to reduce your risk for transmission is to use a condom or other barrier method for every sexual encounter.

Keep reading to learn which STIs can be spread through oral sex, the symptoms to look out for, and how to get tested. ­­

Chlamydia is caused by the bacteria Chlamydia trachomatis. It’s the most common bacterial STI in the United States among all age groups.

Chlamydia can be passed through oral sex, but it’s more likely to be transmitted through anal or vaginal sex. Chlamydia can affect the throat, genitals, urinary tract, and rectum.

Most chlamydia affecting the throat causes no symptoms. When symptoms do appear, they can include a sore throat. Chlamydia isn’t a lifelong condition, and it can be cured with the right antibiotics.

Gonorrhea is a common STI caused by the bacterium Neisseria gonorrhoeae. The CDC estimates there are about 1.14 million new cases of gonorrhea each year, with about half affecting people ages 15 to 24.

Both gonorrhea and chlamydia can technically be passed through oral sex according to the CDC, but the exact risks are challenging to determine. Those engaging in oral sex may also engage in vaginal or anal sex, so the cause of the condition may not be clear.

Gonorrhea can affect the throat, genitals, urinary tract, and rectum.

Like chlamydia, gonorrhea of the throat often doesn’t show any symptoms. When symptoms do appear, it’s usually a week after exposure and can include a sore throat.

Gonorrhea can be cured with the right antibiotics. However, there has been an increase in reports of drug-resistant gonorrhea in the United States and around the world.

The CDC recommends retesting if your symptoms don’t go away after you’ve completed the full course of antibiotics.

It’s also important for any partners to get tested and treated for any STIs to which they may have been exposed.

Syphilis is an STI caused by the bacterium Treponema pallidum. It isn’t as common as other STIs.

According to the CDC, there were 115,045 reported new syphilis diagnoses in 2018. Syphilis can affect the mouth, lips, genitals, anus, and rectum. If not treated, syphilis can also spread to affect other parts of the body, including the blood vessels and nervous system.

Syphilis symptoms happen in stages. The first stage (primary syphilis) is characterized by a painless sore (called a chancre) on the genitals, rectum, or in the mouth. The sore may go unnoticed and will disappear on its own even without treatment.

In the second stage (secondary syphilis), you may experience a skin rash, swollen lymph nodes, and fever. The latent stage of the condition, which can last for years, shows no signs or symptoms.

The third stage of the condition (tertiary syphilis) can affect your brain, nerves, eyes, heart, blood vessels, liver, bones, and joints.

It can also spread to a fetus during pregnancy and cause stillbirth or other serious complications for the infant.

Syphilis can be cured with the right antibiotics. If left untreated, the condition will remain in the body and can cause serious health problems such as organ damage and significant neurological outcomes.

The herpes simplex virus type 1 (HSV-1) is one of two types of the common viral STI.

HSV-1 spreads mainly through oral-to-oral or oral-to-genital contact, causing both oral herpes and genital herpes. According to the World Health Organization (WHO), HSV-1 affects an estimated 3.7 billion people under age 50 around the world.

HSV-1 can affect the lips, mouth, throat, genitals, rectum, and anus. Symptoms of oral herpes include blisters or sores (also called cold sores) on the mouth, lips, and throat.

This is a lifelong condition that can spread even when symptoms aren’t present. Treatment can reduce or prevent herpes outbreaks and shorten their frequency.

HSV-2 is transmitted primarily through sexual intercourse, causing genital or anal herpes. According to the WHO, HSV-2 affects an estimated 491 million people ages 15 to 49 around the world.

HSV-2 can spread through oral sex and, along with HSV-1 can cause serious illnesses such as herpes esophagitis in some people, but this is rare. Symptoms of herpes esophagitis include:

  • open sores in the mouth
  • difficulty swallowing or pain with swallowing
  • chills
  • fever
  • malaise (general unwell feeling)

This is a lifelong condition that can spread even when you don’t have symptoms. Treatment can shorten and reduce or prevent herpes outbreaks.

HPV is the most common STI in the United States. The CDC estimates that about 79 million Americans are living with HPV currently.

The virus can spread through oral sex as often as it does vaginal or anal sex. HPV affects the mouth, throat, genitals, cervix, anus, and rectum.

In some cases, HPV won’t show any symptoms.

Certain types of HPV can cause laryngeal or respiratory papillomatosis, which affects the mouth and throat. Symptoms include:

  • warts in the throat
  • vocal changes
  • difficulty speaking
  • shortness of breath

Several other HPV types that affect the mouth and throat don’t cause warts, but may cause head or neck cancer.

HPV doesn’t have a cure, but the majority of HPV transmissions are cleared by the body on its own without causing problems. Warts of the mouth and throat can be removed through surgery or other treatments, but they may recur even with treatment.

In 2006, the FDA approved a vaccine for children and young adults ages 11 to 26 years to prevent transmission from the most common high-risk HPV strains. These are the strains associated with cervical, anal, and head and neck cancers. It also protects against common strains that cause genital warts.

In 2018, the FDA expanded its approval to adults up to age 45.

The CDC estimates that 1.17 million people in the United States were living with HIV in 2018.

HIV is most commonly spread through vaginal and anal sex. According to the CDC, your risk for spreading or acquiring HIV through oral sex is extremely low.

HIV is a lifelong disease, and many don’t see any symptoms for years. People living with HIV may initially have flu-like symptoms.

There’s no cure for HIV. However, people with HIV can live longer, healthier lives by taking antiviral medications and staying in treatment.

For STI screenings, the CDC advises yearly testing (at least) for chlamydia and gonorrhea for all sexually active women younger than 25 years and for all sexually active men who have sex with men (MSM). MSM should also be screened for syphilis at least annually.

People with new or multiple sex partners, as well as pregnant women, should also have annual STI screenings. The CDC also recommends that all people ages 13 to 64 years get tested for HIV at least once in their lifetime.

You can visit your doctor or a health clinic to get screened for HIV and other STIs. Many clinics offer free or low-cost testing options. What you can expect from a test will differ among each condition.

The types of tests include:

  • Chlamydia and gonorrhea. This involves a swab of your genital area, throat, or rectum, or a urine sample.
  • HIV. An HIV test requires a swab from inside your mouth or blood test.
  • Herpes (with symptoms). This test involves a swab of the affected area.
  • Syphilis. This requires a blood test or sample taken from a sore.
  • HPV (warts of the mouth or throat). This involves a visual diagnosis based on symptoms or pap test.

Although STIs are more commonly spread through sexual intercourse, it’s still possible to acquire them during oral sex.

Wearing a condom or other barrier method — correctly and every time — is the only way to reduce your risk and prevent transmission.

You should get tested regularly if you are sexually active. The sooner you know your status, the earlier you can get treatment.