Though it’s theoretically possible, there are currently no known cases of HIV transmission by oral sex. Some factors that could potentially cause an infection through oral sex is direct contact of seminal fluid (from a person living with HIV) and open sores in your mouth or actively bleeding gums.
Other STIs are more likely to be transmitted through oral sex, including chlamydia and gonorrhea. However, since HIV isn’t transmitted through saliva, the risk of contracting it through receiving or giving oral sex is almost nonexistent.
HIV is most often transmitted during receptive anal and vaginal sex, through the sharing of syringes for injection drug use. However, you can always protect yourself by using a latex condom when giving oral sex to a male partner. You can also use PrEP, a daily pill that is up to 99% effective at preventing HIV in individuals who do not have the virus.