YES. Many people mistakenly believe oral sex is a way to practice safe sex, but it’s not. STIs can be spread during oral sex. To be safe, you should use a condom if the penis is going to touch the mouth. Be sure to use a condom that’s labeled effective against STIs. If your mouth touches the outside or inside of your partner’s vagina (cunnilingus) or anus (anilingus), you can reduce your risk of getting an STI by placing a barrier (sometimes called a "Dental Dam") over the vagina or anus.