How HIV testing works
HIV tests look for one of three things: antibodies your immune system makes, a viral protein called p24, or the virus's genetic material. Which one is used decides how soon after exposure a test can detect an infection.
Diagnik Health Library · Updated
The three test types
- Antibody tests detect antibodies to HIV. All over-the-counter self-tests are antibody tests.
- Antigen/antibody tests detect antibodies plus the p24 antigen and are common in labs and clinics.
- Nucleic acid tests (NAT) look for the virus itself and are used for very early detection or to confirm results.
What an at-home oral-fluid test measures
The OraQuick In-Home HIV Test detects HIV-1 and HIV-2 antibodies in oral fluid collected by swabbing your gums. It gives a preliminary screening result at home in 20 to 40 minutes and does not measure viral load.
Reading a result honestly
- Reactive means antibodies were detected — a preliminary positive that must be confirmed by a clinician.
- Non-reactive means none were detected in that sample, at that time.
- Invalid means the test did not run, usually because the control line is missing.
Tests mentioned in this guide
Frequently asked questions
- Are at-home HIV tests reliable?
- Over-the-counter HIV self-tests are FDA-authorized screening tests. They are reliable as a screen when used exactly as instructed and outside the window period, and any reactive result needs confirmatory laboratory testing.
- Why do reactive results need confirmation?
- Screening tests are designed to catch as many true positives as possible, which means a small number of reactive results are not true infections. Confirmatory testing resolves that.
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Sources
Educational information only, not a medical diagnosis or treatment advice. Screening results always need confirmation by a clinician.
This guide is general health information about screening tests. It is not a diagnosis and does not replace care from a clinician. See our medical disclaimer.