Several sexually transmitted infections (STIs), including chlamydia, gonorrhea, herpes, human papillomavirus (HPV) and syphilis, can be spread through oral sex, according to the Centers for Disease Control and Prevention.

Herpes simplex virus 1 primarily causes cold sores and fever blisters around the mouth while herpes simplex virus 2 causes genital herpes, but the two viruses can be spread from one location to the other. Oral chlamydia and gonorrhea can sometimes cause a sore throat, but they are often asymptomatic. There are simple tests for chlamydia, gonorrhea and syphilis, and all can be treated with antibiotics.

Using a condom, dental dam or other barrier during oral sex can reduce the risk of acquitting of transmitting STIs. A growing proportion of oral cancers are caused by HPV, which can be prevented with a vaccine.