2. Syphilis
“Syphilis is a highly infectious condition, and one of its hallmarks is the development of sores in the mouth,” board-certified ob/gyn Antonio Pizarro, M.D., tells SELF. The sores, which are usually round and open, “combine to make syphilis transmissible through kissing,” says Pizarro. Kissing isn’t the most common way to transmit syphilis—oral, anal, and punani se_x still rank higher. But syphilis rates are currently on the rise, according to the CDC, so it’s good information to have. If you or your partner has syphilis-related sores in your mouth, they (and the virus itself) should clear up with the help of doctor-prescribed antibiotics.
So, what about other STIs? While the chances of passing infections like gonorrhea, chlamydia, and HIV through saliva aren’t usually worth worrying about, that changes if one of you has a cut or sore in your mouth. “Any time there’s an open sore and/or blood present, theoretically an infection could be transmitted orally,” says Pizarro.
