(Last updated 9/27/2013; last reviewed 9/27/2013)
HIV testing shows if a person is infected with HIV. HIV is the virus that causes AIDS. AIDS is the most advanced stage of HIV infection.
HIV testing can detect HIV infection but it can’t tell how long a person has been HIV infected or if the person has AIDS.
HIV testing helps protect your health. Whether testing shows you are HIV-negative or HIV-positive, you can take steps to protect your health.
If you are HIV-negative:
Testing shows that you don’t have HIV. Continue taking steps to avoid getting HIV, such as using a condom during sex. For more information read the AIDSinfo fact sheet on HIV prevention.
If you are HIV-positive:
Testing shows that you are infected with HIV, but you can still take steps to protect your health. Begin by talking to your health care provider about antiretroviral therapy (ART). ART is the use of HIV medicines to treat HIV infection. ART involves taking a combination of HIV medicines every day. ART helps people with HIV live longer, healthier lives. ART also reduces the risk of sexual transmission of HIV. Your health care provider will help you decide when to start treatment and what HIV medicines to take.
The Centers for Disease Control and Prevention (CDC) recommends HIV testing for everyone 13 to 64 years old as part of routine medical care.
CDC recommends HIV testing at least once a year for people at high risk of HIV infection. Factors that increase the risk of HIV infection include:
CDC also recommends that all pregnant women get tested for HIV. Women who test HIV positive take HIV medicines during pregnancy and childbirth to reduce the risk of mother-to-child transmission of HIV. Babies born to HIV-infected women receive HIV medicines for 6 weeks after birth to reduce the risk of mother-to-child transmission of HIV.
Because HIV can be transmitted in breast milk, HIV-infected women in the United States should not breastfeed their babies. In the United States, baby formula is a safe and healthy alternative to breast milk.
The three main HIV tests are the HIV antibody test, the HIV RNA test, and the Western blot test.
HIV antibody test
The HIV antibody test is the most common HIV test. The test checks for HIV antibodies in blood, urine, or fluids from the mouth. HIV antibodies are a type of protein the body produces in response to HIV infection.
Once a person is infected with HIV, it generally takes about 3 months for the body to produce enough antibodies to be detected by an HIV antibody test. (For some people, it can take up to 6 months.) This time period between infection with HIV and the appearance of detectable HIV antibodies is called the window period. During the window period, the level of antibodies in the body is too low to be detected by an HIV antibody test. For this reason, the HIV antibody test isn’t used during the window period.
It usually takes a few days to a few weeks to get results of an HIV antibody test. Some rapid HIV antibody tests can produce results within 30 minutes.
HIV RNA test
An HIV RNA test can detect HIV in a person’s blood within 9 to 11 days after the person is infected with HIV—before the body has produced enough antibodies to be detected by an HIV antibody test.
The HIV RNA test is used during the window period when recent infection is suspected—for example, soon after a person has had unprotected sex with a partner infected with HIV. Immediately after infection, the amount of HIV in the body is very high, which increases the risk of HIV transmission. Detecting HIV at the earliest stage of infection lets a person take steps right away to prevent spreading HIV to others. This includes the option to start taking HIV medicines.
Results from an HIV RNA test are usually available within a few days to a few weeks.
Western blot test
HIV is diagnosed on the basis of positive results from two HIV tests. The first test can be either an HIV antibody test (using blood, urine, or fluids from the mouth) or an HIV RNA test (using blood). A positive result on a first HIV test must be confirmed by a second HIV test (always using blood). The confirmatory test typically used is a different type of antibody test called a Western blot test.
Results from a Western blot test are usually available within a few days to a few weeks. A positive Western blot test result confirms that a person is infected with HIV.
There are two HIV tests approved by the U.S. Food and Drug Administration (FDA) for home use. One test involves collecting a blood sample at home and then sending the sample to a lab for testing. The person using the test must wait about 1 week before calling the lab to get the test results.
The other approved home use test doesn’t depend on a lab for test results. Using the test involves swabbing the gums with a test device to get a sample of oral fluids and then inserting the test device into a test solution. Test results are ready in 20 to 40 minutes.
A positive result on a home HIV test must always be confirmed by a Western blot test done in a health care setting.
Learn more about HIV home test kits approved by FDA.
If you get tested at a doctor’s office or clinic, you can ask for a confidential HIV test. This means that only people allowed to see your medical records will see your test results. If your HIV test results show that you are infected with HIV, this information may be reported to your state health department to be counted in statistical reports. Your name will not be attached to the information.
Some states have “anonymous” testing, which means you don’t have to give your name when you take an HIV test. When you take the test, you receive a number. To get your test results, you give the number instead of your name.