How long for strep test to come back

By Quinn PhillipsMedically Reviewed by David L. Causey, MD

Reviewed: August 27, 2022

Strep throat is an infection caused by bacteria known as Group A streptococcus. (1,2) According to the Centers for Disease Control and Prevention (CDC), there are about 14,000 to 25,000 cases of invasive Group A strep per year in the United States, which results in about 1,500 to 2,300 deaths per year.

It is spread when you are exposed to secretions from an infected person’s respiratory tract, often when that person coughs or sneezes. It is most common in the winter and spring, according to the CDC.

While strep throat usually has symptoms that may lead your doctor to suspect it, these symptoms aren’t always specific. They may overlap with symptoms of a viral infection, which is a much more common cause of a sore throat. Only about 5 to 10 percent of adult sore throat cases are Group A strep, according to the CDC.

It’s important to get tested for, and diagnosed with, strep throat before starting any treatment for your infection.

Once you receive a diagnosis of strep throat, it’s important to begin treatment with antibiotics promptly to prevent any complications.

Strep Throat Symptoms and When to See a Doctor

Strep throat typically presents with symptoms two to five days after you catch it from an infected person.

Symptoms can be mild or severe, and typically include:

• Sore throat that comes on suddenly
• Fever that may begin suddenly (often highest on the second day)
• Red appearance to the throat, sometimes with white patches or pus
• Small red spots toward the back of the roof of your mouth
• Chills and body aches
• Painful swallowing
• Tender, enlarged lymph nodes in your neck
• Headache
• Nausea or vomiting (especially in young children)
• Abdominal pain (2,3)

If you also have scarlet fever — which is caused by the same bacteria as strep throat, and which can appear at the same time — you may also experience:

• A red rash that feels like sandpaper
• Bright red appearance to creases of armpits or groin
• Red, swollen tongue (4)

While it’s important to note any of these symptoms and report them to your doctor when making an appointment, your doctor will also be interested in what symptoms you or your child don’t have.

“If you really just have fever, sore throat, and enlarged lymph nodes in your neck, then strep is more likely to be the cause of your symptoms,” says Nipunie S. Rajapakse, MD, a pediatric infectious disease specialist at the Mayo Clinic in Rochester, Minnesota. (1)

• Runny nose (rhinorrhea)
• Cough
• Vocal hoarseness
• Pink eye (conjunctivitis)
• Oral ulcers
  

Rajapakse estimates that 90 percent of sore throats are caused by a virus, so unless you’re experiencing the telltale signs of strep throat, it’s probably not the cause of your symptoms.

Be sure to see a doctor if you or your child experience any of the following:

• Sore throat along with swollen lymph nodes in your neck
• Sore throat lasting more than 48 hours
• Fever above 101 degrees F or lasting more than 48 hours
• Sore throat along with a rash on the neck or body
• Difficulty swallowing or breathing (3)

What Does Strep Throat Look Like?

Some people believe that you can identify strep throat by its appearance, but this is a widespread misconception, says Rajapakse.

“No doctor or parent can tell whether a child has strep just by looking at the throat,” she emphasizes. Even when a doctor strongly suspects that an infection is strep throat, a throat swab is necessary to confirm the diagnosis.

When strep throat is present, it typically gives a very red appearance to the throat and tonsils. There is often also a white coating on some of or all the reddened areas.

“Some people take the white coating to mean that it’s caused by strep for sure,” Rajapakse says. “But we know that with certain viruses, which are a much more common cause of sore throat in kids, you get this white coating as well.”

The red area in an infected person’s throat may extend to the roof of the mouth, sometimes appearing to “trail off” as red dots in that area.

There may also be visible areas of pus — usually bumpy-looking white or yellow secretions — on the tonsils or back of the throat.

How Do Doctors Diagnose Strep Throat?

To diagnose or rule out strep throat, your doctor will first ask about your history of symptoms and perform a physical examination.

This examination will involve looking at the back of the throat, during which your doctor may take a throat swab right away.

It will also include taking your or your child’s temperature and feeling the neck for enlarged or tender lymph nodes. Your doctor will probably also check the neck and body for signs of a rash.

If your doctor suspects strep throat based on this examination, a throat swab will be tested for the presence of strep bacteria.

Typically, doctors will recommend a test for most children but only test adults if they meet two or more strep criteria, such as having white patches on the tonsils (tonsillar exudates), swollen and tender lymph nodes, fever, or an absence of cough.

There are two tests available: a rapid test and a lab culture test. (5)

A rapid strep test can give results within minutes, Rajapakse says, and is the only test needed if someone tests positive for strep throat.

But if rapid test results come back negative for strep, that doesn’t mean for sure that you don’t have it. “A small percentage of people who have a negative rapid test will have a positive culture,” Rajapakse notes — and the lab test is considered definitive.

If your rapid test results are negative, your doctor will probably order a lab culture test. It can take several days to obtain the results from this test.

Your doctor will most likely start you on a course of antibiotics as soon as you test positive for strep. (5)

If your rapid test results are negative but your doctor strongly suspects that this is erroneous, it’s possible that you’ll be told to start on antibiotics right away, before the lab culture results are in.

If strep throat recurs in you or your child, you might consider investing in a Rapid Response strep test kit. This over-the-counter test involves a throat swab that gets placed into a test tube filled with a mixture of reagents. Once the solution has been mixed, you insert a test strip for five seconds; it can detect strep A in five minutes. According to the Food and Drug Administration, this test has a 97 percent accuracy rate. (6)

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Editorial Sources and Fact-Checking

1. Nipunie S. Rajapakse, MD, Pediatrician and Infectious Disease Specialist at Mayo Clinic.
2. Strep Throat. Centers for Disease Control and Prevention. January 13, 2022.
3. Strep Throat: All You Need to Know. Centers for Disease Control and Prevention. June 27, 2022.
4. Scarlet Fever. Mount Sinai Health Library. January 29, 2022.
5. Strep Throat. Mount Sinai Health Library. July 19, 2021.
6. FDA Executive Summary [PDF]. U.S. Food and Drug Administration. August 16, 2016.
   

Additional Sources

• Group A Streptococcal (GAS) Disease: Surveillance. Centers for Disease Control and Prevention. June 27, 2022.
• Antibiotic Prescribing and Use: Adult Outpatient Treatment Recommendations. Centers for Disease Control and Prevention. October 3, 2017.
• Group A Streptococcal (GAS) Disease: Pharyngitis (Strep Throat). Centers for Disease Control and Prevention. June 27, 2022.

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