How unsafe is it for a girl to give oral sex to a guy who's not wearing a condom?

STD risk: There is a risk of transmission of any/all stds via unprotected oral intercourse just as much as other options. Use condom.

STD risks: Oral sex has potential to transmit a number of sti's. Herpes simplex, hiv, hpv, gonorrhea, chlamydia, syphilis ; hepatitis can be spread via oral sex.

Oral Sex: There are lots of versions of oral sex, but in this scenario, the risk carries almost all of the twelve common stds. An infected penis can pass on herpes, hpv, syphilis, gonorrhea and chlamydia. Infected semen can pass on hiv, hepatitis b and c and syphilis. (syphilis is passed from an infected skin lesion early on in infection and then in semen and blood later in the infection).