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Strep A Test
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Lab Tests

Strep A Test

Strep A tests are used to determine if a sore throat is caused by group A Streptococcus bacteria, which requires antibiotic treatment to prevent serious complications.

What is a strep A test?

Group A Streptococcus is a type of bacteria that causes infections like strep throat. It is most common in children ages 5 to 15. The infection spreads through the air via coughing or sneezing, or by touching contaminated surfaces. There are two types of tests:

  • Rapid strep test: Looks for antigens and provides results in 10–20 minutes.
  • Throat culture: Looks for the bacteria itself; it is more accurate but takes 24–48 hours for results.

Why do I need a strep A test?

Your provider may order a test if you or your child has symptoms such as:

  • Sudden, severe sore throat
  • Pain or trouble swallowing
  • Fever of 101 °F (38 °C) or more
  • Swollen lymph nodes and tonsils
  • White patches or pus on the tonsils
  • Petechiae (tiny red spots on the roof of the mouth)

A rough, red rash spreading from the face may indicate scarlet fever, which also requires antibiotic treatment.

What happens during the test?

A health care professional will use a tongue depressor to hold your tongue down and a special swab to collect a sample from the back of your throat and tonsils. The procedure may cause slight discomfort or gagging.

Understanding Results

If a rapid test is negative but symptoms persist, a throat culture is often performed. If the result is positive, antibiotics are prescribed. It is critical to finish the entire course of antibiotics, even if you feel better, to prevent complications such as:

  • Rheumatic fever (which can damage the heart and joints)
  • Abscesses around the tonsils
  • Sinus or ear infections
  • Glomerulonephritis (a type of kidney disease)

Prevention

To prevent the spread of group A strep, wash your hands frequently, cover your mouth when coughing or sneezing, and disinfect frequently touched objects. Having strep throat once does not protect you from getting it again.

Frequently Asked Questions

ntibiotics should be started as soon as a positive result is confirmed, ideally within 24 hours. Delaying treatment can increase the risk of complications such as rheumatic fever, peritonsillar abscess, or spread of infection.
rapid strep test is ideal for quick decision‑making; it delivers results in 10–20 minutes and is highly useful when symptoms are classic and the likelihood of strep is high. A throat culture is more sensitive and can detect strep even if the rapid test misses it, but it requires 24–48 hours. If the rapid test is negative but symptoms persist, a culture is often ordered to confirm.
negative rapid test does not completely rule out strep. Your clinician may perform a throat culture to double‑check. In the meantime, you can manage pain and fever with acetaminophen or ibuprofen, maintain hydration, and rest. If the culture later turns positive, antibiotics will be prescribed.
Incomplete antibiotic therapy can allow the bacteria to survive, potentially leading to recurrence, antibiotic resistance, and serious complications like rheumatic fever or kidney inflammation. It is essential to finish the entire prescribed course, even if symptoms improve before the medication is finished.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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