Chlamydia Chlamydia is another bacterial infection , and it can also result in pelvic inflammatory disease and fertility problems if left untreated. Great question! However, no scientific studies have been done to show whether or not these factors actually do increase the risk of getting HIV or STI from oral sex. There are many treatment options that keep HIV in check, but there is no surefire way to cure it. Receiving: If you are receiving the delightful thing that is oral sex from a mouth that is infected with this virus, you can end up with a genital outbreak. This super low-risk activity gets a bit higher risk if you have cuts or sores like herpes sores in your mouth. When you break down the math, 80 percent of people carry the herpes simplex virus like cold sores , the most commonly transmitted STI from oral sex; 50 percent of sexually active people have genital warts caused by the human papillomavirus HPV , which, when orally transmitted, is thought to be a cause of head and neck cancers. Chlamydia is passed when the mucous membrane that soft little piece of skin covering all openings comes into contact with secretions of semen or vaginal fluids. Nonetheless there are plenty of things you can do to help lower the risk if you're still nervous. There are free and low-cost options for testing in your area. If you are sexually active, you can do the following things to lower your chances of getting an STD: Being in a long-term mutually monogamous relationship with a partner who is not infected with an STD e. According to the CDC , syphilis sores can be in the mouth as well as on the genitals. Risk: While the exact rate is unknown, the CDC has found that a substantial proportion of people with syphilis got it through oral sex. This may not be true for other STDs — in one study of gay men with syphilis, 1 out of 5 reported having only oral sex. Good luck! My patient, like millions of other horny guys, assumed that oral sex is safe sex , but that's not always true. Oral sex refers to using the mouth to stimulate the penis fellatio , the vagina cunnilingus , or the anus anilingus.