https://www.hiv.gov/hiv-basics/hiv-testing/learn-about-hiv-testing/hiv-testing-overview What Can You Expect When You Go in for an HIV Test? If you take a test in a health care setting, when it's time to take the test, a health care provider will take your sample (blood or oral fluid), and you may be able to wait for the results if it's a rapid HIV test. If the test comes back negative, and you haven't had an exposure for 3 months, you can be confident you're not infected with HIV. If your HIV test result is positive, you may need to get a follow-up test to be sure you have HIV. Your health care provider or counselor may talk with you about your risk factors, answer questions about your general health, and discuss next steps with you, especially if your result is positive. How Soon After Exposure to HIV Can an HIV Test Detect If You Are Infected? No HIV test can detect HIV immediately after infection. If you think you've been exposed to HIV, talk to your health care provider as soon as possible. The time between when a person gets HIV and when a test can accurately detect it is called the window period. The window period varies from person to person and also depends upon the type of HIV test. Most HIV tests, including most rapid tests and home tests, are antibody tests. Antibodies are produced by your immune system when you’re exposed to viruses like HIV or bacteria. HIV antibody tests look for these antibodies to HIV in your blood or oral fluid. It takes time for the body to produce enough antibodies for an HIV test to show that a person has HIV. The soonest an antibody test will detect infection is 3 weeks. Most (approximately 97%), but not all, people will develop detectable antibodies within 3 to 12 weeks (21 to 84 days) of infection. If you have any type of antibody test and have a positive result, you will need to take a follow-up test to confirm your result. A combination, or fourth-generation, test looks for both HIV antibodies and antigens. Antigens are foreign substances that cause your immune system to activate. The antigen is part of the virus itself and is present during acute HIV infection (the phase of infection right after people are infected but before they develop antibodies to HIV). Combination tests are now recommended for HIV testing that’s done in labs and are becoming more common in the U.S. Most, but not all people, will make enough antigens and antibodies for fourth-generation or combination tests to accurately detect infection 2 to 6 weeks (13 to 42 days) after infection. A nucleic acid test (NAT) looks for HIV in the blood. It looks for the virus and not the antibodies to the virus. This test is very expensive and not routinely used for screening individuals unless they recently had a high-risk exposure or a possible exposure with early symptoms of HIV infection. Most, but not all people, will have enough HIV in their blood for a nucleic acid test to detect infection 1 to 4 weeks (7 to 28 days) after infection.