How long should I wait to get tested?

Most HIV tests are antibody tests that measure the antibodies your body makes against HIV. It can take some time for the immune system to produce enough antibodies for the antibody test to detect and this time period can vary from person to person. This time period is commonly referred to as the window period.

Most people will develop detectable antibodies within 2 to 8 weeks (the average is 25 days). Even so, there is a chance that some individuals will take longer to develop detectable antibodies. Therefore, if the initial negative HIV test was conducted within the first 3 months after possible exposure, repeat testing should be considered more than 3 months after the exposure occurred to account for the possibility of a false-negative result. Ninety seven percent will develop antibodies in the first 3 months following the time of their infection. In very rare cases, it can take up to 6 months to develop antibodies to HIV.

Another type of test is an RNA test, which detects the HIV virus directly. The time between HIV infection and RNA detection is 9-11 days. These tests, which are more costly and used less often than antibody tests, are used in some parts of the United States.

For information on HIV testing, you can talk to your health care provider or you can find the location of the HIV testing site nearest to you by calling CDC-INFO 24 Hours/Day at 1-800-CDC-INFO (232-4636) or 1-888-232-6348 (TTY).