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Strep Throat Test: How To Tell You Have It
Updated on November 28, 2022
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Strep Throat Test: How To Tell You Have It

Viral infections are the most common cause of sore throats. An inflamed or swollen throat (pharynx) caused by viruses often only last a day or two.

However, if your sore throat is prolonged, associated with white spots on the tonsils, is severely painful, and/or comes with a high fever, you may have streptococcal pharyngitis or strep throat. The Streptococcus bacteria trigger this infection.

“Strep throat commonly affects children and teenagers. The diagnosis of this infection is crucial because prompt antibiotic usage prevents this bacteria from producing heart complications,” says our in-house expert Dr. Rizza Mira.

A strep throat test can determine if a strep infection causes your sore throat. Medical experts also use it for strep throat diagnosis.

Quick Facts On The Strep Test

  • Detects infection from streptococcus bacteria
  • Has two types — rapid strep test and throat culture

Why Take A Strep Test?

People with symptoms should take the test immediately for quick diagnosis and treatment. Streptococcal bacteria are highly contagious, and anyone can get them.

“There are two methods where a strep infection can be passed on: by inhalation of droplets containing the bacteria and by direct contact with an item infected with the bacteria,” says Dr. Mira.

Infected people can easily spread the bacteria through droplets or mucus when they sneeze or cough. Aside from getting infected, people who come in contact with the bacteria can also easily pass them on.1

You may also develop complications from untreated strep throat, such as rheumatic fever. If left untreated, acute rheumatic fever may even become more severe and cause rheumatic heart disease.2 

Strep bacteria can also potentially injure your kidneys. Acute glomerulonephritis occurs when the tiny filters in the kidney are damaged (glomeruli). This is often a result of untreated strep throat. 3,4

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What Does A Strep Test Check For?

A strep test detects the Streptococcus pyogenes, also known as group A strep (GAS). It’s the leading bacterial cause of acute tonsillopharyngitis or inflammation of the tonsils and pharynx (throat).

A medical expert may need to collect samples from behind your throat or tonsils to test for the bacteria. They'll analyze the specimens through a rapid strep test or a throat culture.

When To Take A Test For Strep Throat

Your doctor or a health care provider orders a strep test when you have a sore throat and other tell-tale signs of a strep throat infection. 

Doctors are also likely to require strep testing in children with sore throats or someone who had close contact with an infected person.

Get yourself tested if you have these symptoms:

  • Recurrent sore throats
  • A fever higher than 101° F
  • Redness in the throat or tonsils with yellow or white patches
  • Difficulty swallowing
  • Loss of appetite
  • Head and body aches 
  • Nausea and vomiting
  • Swollen neck glands
  • Skin rash
  • Hoarseness of voice that lasts more than 2 weeks
  • Signs of dehydration, such as excessive thirst, dry mouth, or decreased urination

Another possible outcome is scarlet fever if your sore throat has a rash or skin redness. Group A strep infection also causes this condition, so strep testing also helps diagnose it.5

However, your doctor may not require testing when you have signs closer to a viral infection instead of a strep infection, such as a runny nose, mouth sores, and cough.6

How Strep Tests Work

You don’t need to do any special preparation prior to testing. However, medical experts must have a diagnosis of strep throat before they prescribe antibiotics.

Rapid Strep Test

Strep tests can determine if the swelling in your throat and tonsils is due to group A strep (GAS) bacteria. 

Doctors use rapid antigen detection tests (RADT), such as rapid strep tests, to detect GAS antigens. Rapid strep testing requires a swab sample from the back of your throat and tonsils. 

The healthcare practitioner will hold down your tongue using a wooden depressor before inserting a cotton swab into your mouth. Then, they'll rub the swab on your throat and tonsils.

Medical technicians usually collect two swab samples. They can use the second specimen for a confirmatory or follow-up test.

This lab test can detect genes, proteins, or other GAS bacteria molecules from your blood specimen within eight minutes. You can get the test results in 10 to 20 minutes. 

A positive result can diagnose strep throat. Your doctor doesn't need further testing to start you on oral antibiotic treatments.

Throat Culture

If your rapid strep test turns out negative, but your doctor believes you have strep infections, they can request a throat culture instead. 

A throat culture is more sensitive than a rapid strep test. It's also more in-depth—sometimes, it finds what rapid tests miss. This is why the results take a little longer and come out in 24 to 48 hours. 

Doctors typically advise a throat culture as a confirmatory test for children or teens with strep throat. They do this to prevent the strep bacteria from causing more serious complications. 

What Your Strep Test Results Mean

A positive rapid strep test result indicates the presence of group A strep. On the other hand, a negative result means the test didn’t find the presence of the bacteria. 

However, doctors usually order a confirmatory throat culture if they still suspect strep throat despite any negative outcomes.

A positive throat culture means you have a strep throat infection. A negative result suggests that a viral infection is likely causing your sore throat instead of a bacterial infection. 

“In the absence of signs and symptoms, a person who tests positive for these strep tests is called a carrier,” says Dr. Mira. 

Can You Take A Strep Test At Home?

Yes, you can take a strep test in the comfort of your home. 

At-home strep tests are similar to the rapid strep tests that doctors use. The test kits include a sterile cotton swab that you’ll use to collect your throat swab specimens.

The test kit usually contains two substances used for analysis (reagents). To test your swab sample, you need to mix the reagents first before adding your cotton swab.

Leave the mixture for a few minutes. Then, take the small stick included in the test kit and soak it in the mixture. 

The stick will indicate your results with a single or a set of lines. If you need help with interpreting the outcome, you may contact your healthcare provider.

However, at-home strep testing shouldn’t replace a doctor’s visit. You must see your doctor for the appropriate use of antibiotic therapy in treating the infection and your symptoms.

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Updated on November 28, 2022
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6 sources cited
Updated on November 28, 2022
  1. Pharyngitis (Strep Throat).” Centers for Disease Control and Prevention.
  2. Rheumatic Fever: All You Need to Know.” Centers for Disease Control and Prevention.
  3. Acute Rheumatic Fever.” Science Direct.
  4. What is Glomerulonephritis?” National Kidney Foundation.
  5. Scarlet Fever: All You Need to Know.” Centers for Disease Control and Prevention.
  6. Don’t Stress Over Strep.” Associates in Family Medicine.
Dr. Rizza Mira
Dr. Rizza Mira
Medical Reviewer
Dr. Rizza Mira is a medical doctor and a general practitioner who specializes in pediatrics, nutrition, dietetics, and public health.

As a pediatrician, she is dedicated to the general health and well-being of children and expecting parents. She believes that good nutrition, a healthy lifestyle, and prevention of illness are key to ensuring the health of children and their families.

When she’s not in the hospital, Rizza advocates and mobilizes causes like breastfeeding, vaccination drives, and initiatives to prevent illness in the community.
Cristine Santander
Cristine Santander
Content Contributor
Cristine Santander is a content writer for KnowYourDNA. She has a B.S. in Psychology and enjoys writing about health and wellness.
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