Doctors are being urged to inform patients that sexual activities other than intercourse—such as oral sex——carry some degree of risk for transmitting HIV and other sexually transmitted diseases, Reuters reports. Researchers from the American College of Obstetricians and Gynecologists recently published their findings in the journal, Obstetrics & Gynecology.

“Most people, including adolescents, are unlikely to use condoms during oral sex, which places them at risk for acquiring an STD,” Richard Guido, MD, said in an ACOG statement. This unlikelihood is partly because of a greater perceived safety compared with intercourse.

While researchers note that oral sex is generally safer than vaginal or anal sex, the viruses that cause genital herpes, genital warts and hepatitis can be transmitted via oral sex. Bacterial STDs—including syphilis, gonorrhea and chlamydia—can also be transmitted this way.

ACOG notes that while generally considered low-risk for transmission when compared to receptive anal or vaginal sex, HIV cases have been linked to oral sex.