What you can expect

HIV is usually diagnosed by testing your blood or a sample of cells taken with a swab from inside your cheek for the presence of antibodies to the virus.

HIV tests vary in how soon they are able to detect infection. The time between when you get the virus and when it can be detected is called the window period. It can take up to three to 12 weeks for your body to make enough antibodies for an antibody test to detect HIV infection.

It usually takes a few days to a few weeks to get results of an HIV test, although rapid HIV tests can produce results in about 20 minutes.

Regardless of the type of screening test used, if you have an initial positive result you'll need follow-up testing to establish an HIV diagnosis.

Rapid HIV testing

Several rapid tests offer highly accurate information within as little as 20 minutes. These tests look for antibodies to HIV using either:

• A sample of your blood, drawn from a vein or a finger prick
• Fluids collected on a treated pad that is rubbed on your upper and lower gums

A positive reaction on a rapid test requires an additional blood test to confirm the results.

Home HIV testing

Home testing involves:

• Collecting an oral fluid sample by swabbing your mouth
• Using a kit to test the sample yourself

You'll get results in 20 minutes. A positive test result means you'll need a follow-up test. The maker of the test offers confidential counseling and referral to follow-up testing sites.

A home blood test is no longer available.

Clinic or lab HIV testing

Doctors' offices or other health care settings will likely follow the CDC recommendations for testing:

• If this is your initial test, you will be given a combination HIV antigen/antibody test.
• If this test is positive, you will then be tested with a second HIV antibody test. This test can tell the difference between the two most common types of HIV, HIV-1 and HIV-2.
• If these two test results conflict, a third test called an HIV-1 RNA test (nucleic acid amplification test) will look directly for HIV in your blood.

No test can confirm HIV infection immediately after you're exposed. Tests that provide the earliest results are those that:

• Look for antigens — proteins that develop within the first few weeks after infection
• Evaluate your blood for genetic material from the virus

Tests that detect antibodies take longer. To get accurate results, you'll need to have been infected for at least three weeks.