What is the Window Period for HIV Testing?

The HIV testing window period ranges from 10 days to 3 months, depending on the test type used. A laboratory antigen/antibody test using blood from a vein can usually detect HIV 18-45 days after exposure. A rapid antigen/antibody finger-stick test may take 18-90 days., while older antibody-only tests require 23-90 days. A nucleic acid test, which looks for HIV in the blood, can usually detect infection 10-33 days after exposure and is generally more expensive than other HIV tests. The window period exists because it takes time for a test to detect HIV itself, an HIV antigen, or antibodies produced by the immune system. During this time, you may test negative despite being infected and potentially contagious. Testing and repeat-testing times depend on the type of test and whether you have taken HIV prevention medicines, so ask a healthcare provider when your result will be conclusive. If a possible exposure occurred within the past 72 hours, seek urgent medical care to ask about post-exposure prophylaxis (PEP); do not wait to be tested before seeking help.