Why use condoms? Outside of abstinence, condoms are the only form of protection that can both help stop the transmission of sexually transmitted diseases such as HIV and prevent pregnancy. Whether you're engaging in vaginal, anal, or oral sex, condoms are recommended for all sexually active people who are not in monogamous relationships. If you share sex toys, you'll want to cover them with condoms to prevent the spread of STD's. And, never reuse the same condom when engaging in both vaginal and anal intercourse.