No HIV test can detect HIV immediately after infection. That’s because of the window period—the time between HIV exposure and when a test can detect HIV in your body. The window period depends on the type of HIV test. A nucleic acid test can usually detect HIV the soonest (about 10 to 33 days after exposure). Learn more about the window period for each HIV test. If you think you’ve been exposed to HIV in the last 72 hours, talk to a health care provider, an emergency room doctor, or an urgent care provider about post-exposure prophylaxis (PEP) right away. Download and Share