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Strep Throat Test: How To Tell You Have It
Updated on April 4, 2023
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At Home Health
Strep Throat Test: How To Tell You Have It

Key Takeaways

Viral infections are the most common cause of sore throats that often only lasts a day or two. However, if you have a prolonged sore throat and white spots on the tonsils, you may have streptococcal pharyngitis or strep throat. 

Strep throat is severely painful and may come with a high fever. It’s an infection triggered by the Streptococcus bacteria.

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

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

Quick Facts On The Strep Test

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

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What Does A Strep Test Check For?

A strep test detects the Streptococcus pyogenes, or group A streptococcus (GAS). It’s the leading bacterial cause of acute tonsillopharyngitis

Acute tonsillopharyngitis is the inflammation of the tonsils and pharynx or 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.


Strep throat is a severe bacterial infection caused by Streptococcus bacteria affecting mainly children and teenagers. A strep test can detect the presence of group A streptococcus (GAS) bacteria—the leading cause of acute tonsillopharyngitis, or inflammation of the tonsils and pharynx. The test can be done using either a rapid strep test or a throat culture and is crucial to diagnose the infection promptly.

Why Take A Strep Test?

People with strep throat symptoms should take the test immediately for quick diagnosis and treatment. Streptococcal infections 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. Acute rheumatic fever may become more severe and cause rheumatic heart disease if untreated.2 

Strep bacteria can also potentially injure your kidneys. An untreated strep throat may damage the tiny filters in the kidney— or the glomeruli—leading to acute glomerulonephritis.3,4


Strep throat is a severely painful sore throat caused by the Streptococcus bacteria. A strep throat test can diagnose if the strep throat bacteria is causing your symptoms. It helps your doctor give proper treatment to prevent the bacteria's spread and avoid further health complications.

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 symptoms of strep throat infection

Doctors are also likely to require strep testing in children with sore throats or someone who had close contact or shared personal items 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 or lymph nodes
  • Skin rash
  • Hoarseness of voice that lasts more than two weeks
  • Signs of dehydration, such as excessive thirst, dry mouth, or decreased urination

Scarlet fever is another possible diagnosis if your sore throat comes with a rash or skin redness. Scarlet fever is a bacterial illness following a GAS infection, causing distinct pink-red skin bumps. 

Since GAS bacteria also cause this condition, strep testing helps diagnose scarlet fever.5

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


Doctors typically order a strep test when a person has symptoms of a strep throat infection, including recurrent sore throat, fever, redness in the throat or tonsils, and so on. Strep testing is also required for children with sore throats and those who had close contact with an infected person. However, strep testing may not be necessary when the symptoms suggest a viral infection rather than a strep infection.

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 test (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 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. It 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. 


Your doctor can test you for strep throat using a rapid strep test or a throat culture. If you have a positive result on the rapid strep test, you're doctor can start you on medications. If your results are negative, but you have signs of strep throat, your doctor can request a throat culture to confirm.

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 adverse 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.

Strep Throat Treatments

Once your doctor diagnoses you with strep throat, they’ll prescribe the proper antibiotic, but only when needed. Antibiotics prevent the spread of bacteria. But some people, like carriers, usually don't need antibiotics.

Carriers don't have symptoms, so they are less likely to transmit the infection to others. They also have a low risk of getting health complications.

Antibiotics can help make you feel better quickly by reducing your symptoms. It can also help prevent health complications like rheumatic fever.

You must take your medication strictly as your doctor prescribed. Remember to finish the treatment even when you no longer feel sick. Stop your medication only when advised by your doctor. 

Can You Take A Strep Test At Home?

Yes, you can take a strep test at 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 interpreting the outcome, contact your healthcare provider.

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


A positive rapid strep test result means that group A strep is present, while a negative result means that the test didn't detect the bacteria. Doctors may order a confirmatory throat culture if they still suspect strep throat despite a negative rapid strep test result. Once diagnosed with strep throat, they may prescribe antibiotics to reduce symptoms and prevent health complications.

While at-home strep tests are available and more convenient, they should not replace a doctor's visit. See your doctor if you have symptoms of Strep throat for appropriate treatment and antibiotic therapy.

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Updated on April 4, 2023
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6 sources cited
Updated on April 4, 2023
  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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