Is Strep Throat Contagious?

Strep throat is an infection in the throat and tonsils caused by bacteria called group A Streptococcus, also known as Streptococcus pyogenes. This group of bacteria can also cause other infections, including scarlet fever, pneumonia, sepsis, toxic shock syndrome, and necrotizing fasciitis, which can be life-threatening.

While strep throat only accounts for a small number of sore throats, it is generally more common in children (ages 5 to 15) than adults. This article will explore how strep throat is contagious, its causes, risk factors, treatment, and prevention.

Girl with sore throat talks to healthcare provider

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Is Strep Throat Contagious?

Strep throat is highly contagious and can spread quickly from person to person through close contact. Individuals with strep throat can be contagious for a few days before they start showing symptoms. This means that someone who has not gotten sick yet can spread the disease.

How Do I Know If I Have Strep Throat?

Common symptoms of strep throat include a sore throat that comes on quickly and causes pain with swallowing. Other signs include fever, red and swollen tonsils (sometimes with white patches or a streak of pus), swollen lymph nodes in the neck, petechiae (tiny red spots on the roof of the mouth), and more.


Strep throat is caused by a group of bacteria known as Streptococus pyogenes. It is typically transmitted from person to person through saliva or secretions that contain the bacteria. People can also pass strep throat through coughing, sneezing, and touching people or contaminated objects (doorknobs, door handles, utensils, etc.).

The bacteria are less commonly transmitted through food or water. Since you are unlikely to get strep throat from animals, the risk of getting infected from pets is very low.

Risk Factors

Some factors can increase your risk of contracting strep throat. They include:

  • Young age: Strep throat occurs frequently in children ages 5 to 15 and is rare in children under 3).
  • Close contact/spending time in crowded settings: This includes spending time with someone who has strep throat in schools, day care centers, or large venues.
  • The time of year: Strep throat can occur year-round, but it has seasonal variations. Infections are more common in late winter and early spring.
  • Genetics: According to a 2019 study, researchers found that kids with recurring strep throat tended to have smaller germinal centers in their tonsils, which usually recognize and fight infections. They also were more likely to have family members who had tonsillectomies (surgical removal of the tonsils).
  • Weakened immune system: This increases the susceptibility for people to get strep throat.


Antibiotics are the most commonly used medications to treat bacterial infections by preventing them from growing or killing them. To treat strep throat, your healthcare provider may prescribe you penicillin or amoxicillin.

However, if you are allergic to penicillin your doctor may prescribe a cephalosporin such as Keflex (cephalexin) or medication from a different “family” of antibiotic drugs that is unlike penicillin.

Additionally, someone who tests positive for strep throat but has no symptoms (called a carrier) does not typically need antibiotics. This is because carriers are less likely to spread the bacteria to others and very unlikely to get complications.

However, always consult your healthcare professional if you believe you or someone you know may be a carrier for strep throat to determine the best course of treatment.

The list below highlights some of the benefits of antibiotics. They include:

  • Decreasing how long someone is sick
  • Decreasing symptoms
  • Preventing the bacteria from spreading to others
  • Preventing serious complications such as rheumatic fever

It is essential to finish your course of antibiotics even if you are feeling better, as the remaining bacteria can continue to multiply. When this happens, bacteria can become resistant to the antibiotics, and cause further harm to the body. In some cases, it can develop into sepsis (blood infection), which is a life-threatening condition.

Complications of Strep Throat

Although uncommon, complications can occur after a strep throat infection. This can happen if the bacteria spread to other parts of the body. Complications can include:

  • Abscesses (pockets of pus) around the tonsils
  • Swollen lymph nodes in the neck
  • Sinus infections
  • Ear infections
  • Rheumatic fever: An inflammatory condition of the heart, joints, brain, and skin that can develop if a group A Streptococcus infection is not fully treated
  • Post-streptococcal glomerulonephritis: A rare kidney disease

When to See a Doctor

While strep throat is not usually dangerous, it can sometimes cause medical emergencies. However, this is rare. Seek medical care immediately if you have strep throat and experience the following signs and symptoms:

  • Trouble breathing or shortness of breath
  • Dizziness, feeling faint, or passing out
  • Blue or pale lips or fingers
  • Trouble swallowing


People can get strep throat more than once. Having strep throat does not protect someone from getting it again in the future. While there is no vaccine to prevent strep throat, there are things people can do to protect themselves and others. These include:

  • Practicing good hygiene: This includes washing your hands often (with soap and warm water for at least 20 seconds), especially after coughing or sneezing and before preparing food or eating. You should also wash glasses and utensils after a person who is sick uses them. Practicing good hygiene is the best way to keep from getting or spreading group A strep.
  • Stay home and take your antibiotics if you have strep throat: Your healthcare provider will likely prescribe antibiotics for strep throat. Stay home from work or school until you no longer have a fever and have taken antibiotics for at least 12 hours.

Take Your Full Antibiotic Prescription

Do not stop taking antibiotics even if you are feeling better (unless advised to do so by your healthcare provider). This prevents the growth of antibiotic-resistant bacteria.


Strep throat is an infection in the throat and tonsils caused by group A Streptococcus bacteria. It is highly infectious and can be transmitted from person to person through close contact or by touching infected surfaces. It also produces painful symptoms such as sore throat, red and swollen tonsils, fever, and swollen lymph nodes.

There are many risk factors for strep throat, including age, the time of year, genetics, a weakened immune system, and if you do not finish your course of antibiotics. If you have strep throat, antibiotics are the most commonly used medications your healthcare provider will prescribe.

A Word From Verywell

If you have strep throat, it is crucial for you to get plenty of rest, stay hydrated, and eat well, even if swallowing is painful. This will ease the recovery process and help you feel better.

Additionally, it is essential that you discuss with your doctor when you can resume daily activities, such as school or work, without running the risk of infecting others. If your doctor prescribes you antibiotics, make sure to complete your medication even if you're feeling better to prevent the growth of antibiotic-resistant bacteria, which can be harmful to the body.

That said, you should not expect to experience serious long-term consequences with strep throat, and you should expect to improve within a week. If your symptoms do not improve, get worse, or if you are not feeling better after taking antibiotics after 48 hours, consult your doctor as soon as possible.

Frequently Asked Questions

  • How long does strep throat last?

    Once a person has contracted the group A Streptococcus bacteria, they can become ill after roughly two to five days. A person will begin to feel better after taking antibiotics for one to two days. If you do not feel better after taking antibiotics for 48 hours, consult your doctor.

  • What does strep throat look like?

    People with strep throat have red and swollen tonsils (sometimes with white patches or streaks of pus) that can be very painful. Additionally, tiny red spots on the area at the back of the roof of the mouth may also be visible.

  • How long is strep throat contagious?

    You can stay contagious for up to a month if you don't get treated. However, you are no longer contagious after 24 to 48 hours of antibiotic treatment.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Centers for Disease Control and Prevention. Strep throat: all you need to know.

  3. Dan J, Havenar-Daughton C, Kendric K, et al. Recurrent group A Streptococcus tonsillitis is an immunosusceptibility disease involving antibody deficiency and aberrant TFHcellsSci Transl Med. 2019;11(478):eaau3776. doi:10.1126/scitranslmed.aau3776

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  6. Centers for Disease Control and Prevention. Post-streptococcal glomerulonephritis: all you need to know.