What Is the Incubation Period for Strep Throat?

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If you have a child or have been a child, you likely know about strep throat. Strep throat is a contagious bacterial infection of the throat that can be quite painful. It is most common in school-age children between the ages of 5 and 15 but can affect anyone. Because it is caused by a bacteria, it nearly always needs to be treated with antibiotics.

Strep often spreads easily in schools because kids aren't the cleanest creatures on the planet and they like to share germs, even when they don't like sharing much else.

Once parents hear that strep throat is making the rounds in school, many wonder how long it will be before they will know if their child has it. What they want to know is how long the incubation period is.

What Does Incubation Period Mean?

The incubation period is defined as the time between exposure to germs and when you first start to have symptoms of an illness. The incubation period of an illness varies depending on the infection and can be anywhere from a few hours to weeks, months or years.

The typical incubation period for strep throat is 2 to 5 days, with the average being 3 days. This means that it will be about 3 days from the time you are exposed to the illness to the time you start having symptoms.

How Long Are You Contagious?

If you are sick with strep throat, you will be contagious until you have been on antibiotics for at least 24 hours. However, your symptoms may last longer than that.

It is important to take all of your antibiotics as prescribed. Stopping them as soon as you feel better can mean the infection is only partially treated and it increases the risk of antibiotic resistance.

If you have been infected with the bacteria and are not on antibiotics, you could be contagious for up to three weeks, even if you don't have symptoms.

Some people are considered carriers of Group A Streptococcus (which causes strep throat). This means they will test positive for the bacteria even if they don't have symptoms. It is typically not necessary to treat strep carriers unless it is suspected that they are spreading the illness to others in the family repeatedly.

It's also important to know the symptoms of strep throat. Most people experience fever, sore throat, and red tonsils. Some may have a red, sandpaper-like rash (known as scarlet fever). Others may have abdominal pain, vomiting, or a headache as well. If you or your child has symptoms of an upper respiratory infection such as congestion and cough, it is highly unlikely that an accompanying sore throat is caused by strep. Some people are incorrectly diagnosed with strep throat when they have these symptoms.


It is very important to seek treatment for strep throat, as leaving it untreated can lead to very serious complications such as rheumatic fever. Although rheumatic fever is rare in the U.S. now, prior to the discovery of antibiotics, it was a leading cause of death among children. It is still common in developing countries around the world.

It's also important to know that not all sore throats are caused by strep.

Many people experience sore throats when they have a viral illness. If your health care provider tests you for strep and the rapid test is negative, it can be sent for culture. Throat culture results should be back in a day or two. If your sore throat is caused by a virus instead of a bacteria like Group A Streptococcus, taking antibiotics will not help.

Strep throat cannot be diagnosed by sight alone. No one should look at your throat and tell you that you have strep. Although some people believe the presence of "white patches" on the tonsils indicates strep throat, this isn't the case. These spots can be present with viruses as well.

If you or your child has a sore throat and additional symptoms of strep throat, contact your health care provider to be tested and treated appropriately. Common antibiotics prescribed to treat strep throat include amoxicillin and penicillin. Antibiotics such a cephalexin, clindamycin, or azithromycin may be prescribed for people that are allergic to penicillin.

A Word From Verywell

Strep throat is a common diagnosis among school-age children. Before you give your child antibiotics, make sure you get an accurate diagnosis. Knowing how long it will take for symptoms to appear and how long your child might be contagious is always helpful, no matter what illness you are dealing with. 


CDC. Group A Strep | Strep Throat | For Clinicians | GAS.

MedlinePlus Medical Encyclopedia. Strep throat.