Oral sex can cause infection what type of infection?

Some STDs, not all: The most common STDs transmitted by oral sex are gonorrhea, nongonococcal urethritis (NGU), and herpes due to type 1 HSV. Chlamydia, HSV2, and human papillomavirus are possible but uncommon. There is little or no risk for HIV. But actual risk depends a lot on whether you mean fellatio (oral-penile contact) or cunnilingus (oral-vaginal). And the risks are different for the giver and receiver.