Can you catch hiv by swallowing a drop of blood of someone one else's scab that has been exposed to air?
Hello, and thanks for the question. Taking a drop of blood into your mouth will likely never expose you to HIV and as you note, blood that has been exposed to air will not be infectious.
Saliva contains enzymes that actually break down HIV and if you have no pre-existing sexually transmitted infections, poor overall health, including poor oral; health you should not be worried about HIV from a drop of blood. Taking blood directly into your mouth from a person living with HIV is considered a low risk for infection.