While you cannot get pregnant from it, there are still several risks of unprotected oral sex. When you have unprotected oral sex, you risk contracting several STDs, including herpes and HIV. The person performing the act is more likely to get an STD from the person receiving it.
Although the risk is much lower for unprotected oral sex than for unprotected vaginal or anal sex, you can still get HIV/AIDS from oral sex. Your risk increases if you have a partner who is known to have the infection or a partner who uses IV drugs or sleeps with other people. The virus can be transmitted from a person's semen or vaginal fluids into a cut or ulcer in your mouth.
Unprotected oral sex also carries the risk of spreading herpes, another incurable virus. You can give your partner herpes if your practice oral sex on her while you have a cold sore. Likewise, she can spread herpes to you if she has a lesion on her genitals. If either of you have a sore or lesion, you should abstain from oral sex until they clear up.
The risks of unprotected oral sex also include several curable STDs, such as gonorrhea, chlamydia and syphilis. If you have oral sex with a partner who has gonorrhea or chlamydia, you are likely to get the infection in your throat. Symptoms of oral gonorrhea or chlamydia are often similar to strep throat.
You can protect yourself during oral sex by using a condom on the penis or by creating a barrier between the mouth and vaginal or anal areas. Use a dental dam for the barrier or cut up a condom and use that as a barrier. Make sure the condom does not have spermicide on it, which can damage your taste buds.