How Long Does Strep Test Take? Guide

A rapid strep test gives results in about 5 to 10 minutes. A throat culture, which is more accurate, takes 24 to 48 hours to confirm. Which test you get depends on your symptoms, your doctor’s judgment, and whether a quick answer is needed.

What is a strep test?

A strep test checks for group A Streptococcus bacteria, the most common cause of bacterial sore throat (strep throat). There are two main types. The rapid antigen detection test (RADT) looks for pieces of the bacteria in a throat swab. The throat culture swabs your throat and then lets any bacteria grow in a lab dish over a day or two.

Strep throat is not the same as a viral sore throat. A virus causes most sore throats, and antibiotics do not help viral infections. A strep test helps your doctor decide if antibiotics are needed.

How long does the rapid strep test take?

The rapid strep test itself takes about 5 to 10 minutes. The nurse or doctor swabs the back of your throat, then a lab tech or clinician mixes the swab with chemicals that detect strep antigens. Results appear on a test strip or card within minutes.

But the total time in the doctor’s office or clinic may be longer. You still need to check in, wait for the clinician, and get the swab done. The actual test processing time is very short.

If the rapid test is positive, your doctor can start antibiotics at that visit. If it is negative, you may still need a throat culture to rule out strep completely.

How long does a throat culture take?

A throat culture takes 24 to 48 hours to produce a final result. The swab sample is sent to a microbiology lab. Technicians spread it onto a special plate (blood agar) that encourages strep bacteria to grow if they are present. It usually takes overnight for enough growth to be visible.

Some labs may read the plate at 24 hours. If no growth is seen, they often recheck at 48 hours to be sure. Very rarely a lab may hold the culture longer, but 48 hours is the standard cutoff for a negative result.

Your doctor’s office will usually call you or have you check a patient portal for the result.

Why might you need both tests?

Many doctors use a two-step approach. The rapid test gives a fast answer, but it is not perfectly accurate. Research consistently shows the rapid test catches about 85 to 95 percent of true strep cases. That means 5 to 15 percent of people with strep get a false negative rapid test.

Because of this, current guidelines from groups like the Infectious Diseases Society of America suggest that children and teens with a negative rapid test should also get a throat culture. For adults, the risk of strep is lower, so some doctors skip the culture if the rapid test is negative and symptoms do not strongly suggest strep.

If your rapid test is positive, no culture is needed. The result is reliable enough to start treatment. If it is negative but you have classic strep symptoms — fever, swollen tonsils with white patches, tender neck lymph nodes, no cough — your doctor may still send a culture to be safe.

What happens during the test?

The test itself is quick but uncomfortable for a few seconds. You tilt your head back, open your mouth wide, and say “ah.” The clinician presses your tongue down with a wooden depressor and rubs a sterile cotton swab over the back of your throat and both tonsils. This may trigger a gag reflex, but it lasts only a moment.

The same swab can be used for both the rapid test and the culture. Often the clinician does the rapid test in the office and sends the swab to a lab for culture at the same time. This way you get the rapid result right away and the culture result later if needed.

What to do while waiting for results

If you have a rapid test, you will know in minutes, so waiting is not an issue. If your doctor sends a culture, you may have to wait 24 to 48 hours for the answer.

While you wait, you can treat symptoms with over-the-counter pain relievers like acetaminophen or ibuprofen. Warm salt water gargles (half teaspoon salt in 8 ounces warm water) can soothe a sore throat. Drink plenty of fluids. Rest if you feel tired.

Importantly, do not take antibiotics unless they are prescribed. Taking leftover antibiotics or someone else’s medication can be unsafe and may not work against the bacteria causing your infection. Antibiotics also do not help if your sore throat is from a virus.

If your culture comes back positive, your doctor will call in a prescription or ask you to pick up antibiotics. Strep throat is treated with penicillin or amoxicillin in most cases, unless you have an allergy. Treatment shortens the illness, reduces the chance of complications, and makes you less contagious within about 24 hours.

When to see a doctor for a sore throat

Most sore throats are viral and get better on their own. But strep throat needs antibiotic treatment to prevent complications like rheumatic fever or kidney inflammation. You should see a doctor if you have:

• A sore throat that comes on suddenly and is painful when swallowing
• Fever over 101°F (38.3°C)
• Swollen, red tonsils with white or yellow patches
• Tender or swollen lymph nodes on the front of your neck
• No cough, runny nose, or other cold symptoms

Strep throat is most common in children ages 5 to 15, but adults can get it too. Strep is spread by respiratory droplets — coughing, sneezing, sharing cups — so good hand hygiene helps prevent it.

Can a strep test be done at home?

Home strep test kits are sold at pharmacies and online. They work the same way as the rapid test in a doctor’s office. You swab your own throat and mix it with the test solution.

However, home tests have some important limits. Studies show that people often swab the wrong spot or do not get a good sample. This can lead to false negatives. Also, you still need a doctor to interpret the result and prescribe antibiotics if needed. Most doctors recommend seeing a clinician for a sore throat rather than relying on a home test alone.

Comparison of strep test types

Note: Sensitivity means how often the test correctly identifies someone who has the infection. The rapid test’s lower sensitivity is why a negative rapid test may still need a culture.