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Rapid Tests
URL of this page: https://medlineplus.gov/lab-tests/rapid-tests/

Rapid Tests

What are rapid tests?

Rapid tests, also known as rapid diagnostic tests or RDTs, are easy-to-use tests that provide quick results, usually in 20 minutes or less. Most standard tests have to be sent to a lab, and you have to wait for the results. With a rapid test, you can have the test done and get the results at your provider's office or a clinic. For some of these tests, you can also do them and get the results at home.

Rapids tests usually include the following steps:

  • You provide a sample of your body fluid, such as blood, urine, saliva, or nasal secretions.
  • The sample is mixed with a special substance that will cause a chemical reaction if a disease or other condition is present.
  • The results show on a dipstick or rapid test cassette:
    • A dipstick is a thin, plastic strip coated with chemicals. If the test is positive, the dipstick will change color when placed in the sample.
    • A rapid test cassette is a small plastic case with a well that holds the sample. The well shows a letter or a symbol to indicate the result.

Most rapid tests can provide quick, reliable results, but the results are not always as accurate as standard lab tests. The accuracy of your test results may be affected by:

  • The type of test used
  • How the test is stored and transported
  • The type of specimen taken
  • Your symptoms
  • When your symptoms started
  • What you are testing for
  • Using a test that is past its expiration date

Other names: rapid diagnostic tests, RDT's point-of-care tests

How are they used?

Rapid tests are most often used to diagnose infectious diseases, including:

Rapid tests are also used in certain home-based tests, such as pregnancy tests.

What are the advantages and disadvantages of rapid tests?

The advantages of rapid tests include:

  • Fast results. This may allow you to get treatment faster. Faster treatment can reduce the severity of your symptoms and may help prevent the spread of disease.
  • Easy to use. They can be done by non-medical workers and volunteers who have been trained to do the test. You may even be able to perform a rapid test on yourself.
  • Little or no special equipment is required. This is especially useful in areas with limited resources or access to specialized labs.

The disadvantages of rapid tests include:

  • Lower sensitivity than lab tests. Sensitivity means how well a test can identify a disease or condition. Rapid tests are not as good as lab tests at finding diseases in the earliest stages of infection.
  • False negatives are more common. A false negative result means your test shows you don't have a disease or condition, but you actually do have it.

Because of these possible disadvantages, the instructions for some tests (such as over-the-counter COVID-19 tests) recommend doing the test again after a certain period of time if you got a negative result. A negative result means that the test showed that you don't have the disease.

Your health care provider may take a second sample and send it to a lab for testing to confirm or rule out the results of a rapid test. But you may still be able to get treatment and help prevent the spread of disease while you wait for lab results.

References

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  2. Centers for Disease Control and Prevention [Internet]. Atlanta: U.S. Department of Health and Human Services; COVID-19: Testing for COVID-19; [reviewed 2024 Aug 24; cited 2024 Aug 24]; [about 3 screens]. Available from: https://www.cdc.gov/covid/testing/
  3. Centers for Disease Control and Prevention [Internet]. Atlanta: U.S. Department of Health and Human Services; Influenza (Flu): Rapid Influenza Diagnostic Tests; [reviewed 2016 Oct 25; cited 2024 May 8]; [about 5 screens]. Available from: https://www.cdc.gov/flu/hcp/testing-methods/clinician_guidance_ridt.html
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  7. FDA: U.S. Food and Drug Administration [Internet]. Silver Spring (MD): U.S. Department of Health and Human Services; Coronavirus (COVID-19) Update: FDA Authorizes Antigen Test as First Over-the-Counter Fully At-Home Diagnostic Test for COVID-19; 2020 Dec 15 [cited 204 May 8]; [about 2 screens]. Available from: https://www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-fda-authorizes-antigen-test-first-over-counter-fully-home-diagnostic
  8. FDA: US Food and Drug Administration [Internet]. Silver Spring (MD): U.S. Department of Health and Human Services; COVID-19 Test Basics; [current as of 2023 Sep 7; cited 2024 May 8]; [about 4 screens]. Available from: https://www.fda.gov/consumers/consumer-updates/covid-19-test-basics
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  11. Mayo Clinic [Internet]. Mayo Foundation for Medical Education and Research; c1998-2021. Urinalysis: Overview; [cited 2024 May 8]; [about 6 screens]. Available from: https://www.mayoclinic.org/tests-procedures/urinalysis/about/pac-20384907
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  14. ResearchGate [Internet]. ResearchGate GmbH; c2008-2021. Example of RDT Cassettes; [cited 2024 May 8]; [about 7 screens]. Available from: https://www.researchgate.net/figure/Example-of-RDT-cassettes-Most-of-the-cassettes-have-separated-wells-for-sample-and_fig2_49830148
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  17. Verywell Health [Internet]. New York: About, Inc.; c2024. Why Your Rapid Flu Test Was Negative; [updated 2024 May 3; cited 2024 May 8]; [about 5 screens]. Available from: https://www.verywellhealth.com/why-was-my-flu-test-negative-770309
  18. World Health Organization [Internet]. Geneva (SUI): World Health Organization; c2024. Advice on the use of point-of-care immunodiagnostic tests for COVID-19; 2020 Apr 8 [cited 2024 May 8]; [about 4 screens]. Available from: https://www.who.int/news-room/commentaries/detail/advice-on-the-use-of-point-of-care-immunodiagnostic-tests-for-covid-19#
  19. World Health Organization [Internet]. Geneva (SUI): World Health Organization; c2024. Simple/Rapid Tests; 2014 Jun 27 [cited 2024 May 8]; [about 1 screen]. Available from: https://www.who.int/news-room/q-a-detail/simple-rapid-tests

The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.