QUESTION
How long does it take for HIV to show up in a blood test?

ANSWER
The HIV test is an antibody test that measures the body's reaction to the HIV virus. It takes up to three months after infection for the antibody to become present. That's why we call the period after exposure before an HIV-positive test the "window period" -- when people can actually be infected but have a negative or normal antibody test.

Doctors recommend a repeat test six months after the first to make sure the "window period" was truly negative. Most sexually active people at risk for HIV have interpreted this as the need to get an HIV test every six months. This is a not a bad idea and should be accompanied by STD tests at the same time.

To your health,
Dr. K