What is Strep Throat?

What is Strep Throat?

Strep throat is an infection of the throat or tonsils caused by streptococcus bacteria. Strep throat affects people of all ages and is most common in children. Symptoms of strep throat include throat pain, red and swollen tonsils, and fever. The treatment for strep throat is antibiotics, which help people feel better in a day or two and prevents complications.

Is strep throat contagious?

Strep throat is contagious. Strep bacteria spreads through small drops from an infected person's mouth or nose when the person coughs, sneezes, and talks and enter the mouths and noses of other people nearby. These people may also get infected. It takes a few days for someone exposed to strep bacteria to develop symptoms of strep throat.

Types of Strep Bacteria


Strep is short for a type of bacteria that is called streptococcus. There are several groups of streptococcus bacteria. Group A and group B streptococcus cause most of the strep infections in people.

Groups of streptococcus bacteria that cause strep infections in people are:

  • Group A strep can cause different infections in people. Some of these can be mild infections but some of the group A strep infections can be serious and even deadly. Group A strep infections include:
    • Strep throat which is common in children. Symptoms include a sore, red throat often with fever.
    • Scarlet fever is an illness that sometimes follows strep throat.
    • Impetigo is a skin infection.
    • Cellulitis is a common bacterial skin infection that can be serious. Cellulitis often affects the lower legs but can also affect the arms and the face. The affected skin may become red, swollen, and warm and can cause pain.
    • Necrotizing fasciitis(flesh-eating disease) is a rare bacterial infection that spreads quickly in the body and can be deadly. Group A strep is the most common cause of necrotizing fasciitis. The bacteria enter the body through a wound in the skin caused by injury, burns, and other causes. Necrotizing fasciitis requires urgent medical interventions for diagnosis and treatment.
    • Toxic shock syndrome is a rare, life-threatening complication of certain bacterial infections, including toxins that are produced by group A strep bacteria.
  • Group B strep is bacteria that are often found in the body and can cause serious illness in newborns including blood infections, pneumonia, and meningitis. If a pregnant woman has group B strep, an intravenous antibiotic is given during labor. Group B strep can cause pneumonia, blood, skin, and urinary tract infections in adults especially people who are 65 or older and people of all ages who have other health issues.
  • Groups C and G strep are also commonly found in people and can cause sore throat like group A strep.

Signs & Symptoms of Strep Throat


Strep throat is usually a mild infection, but it can be painful. A primary care doctor can help infected people feel better quickly by diagnosing and treating the infection.

Signs and symptoms of strep throat include:

  • Throat pain
  • Swallowing causes pain
  • Fever
  • Red and swollen tonsils, sometimes with white patches
  • Red spots on the roof of the mouth
  • Swollen lymph nodes in the neck
  • Headache or body aches
  • Nausea or vomiting, typically in children
  • Rash

Strep throat symptoms in children

Strep throat is most common in school-age children who attend daycare centers and schools. People who are infected spread the bacteria by talking, coughing, or sneezing, around other people. Children in daycare centers and schools tend to be in close contact with other children and spreading the bacteria is common.

In addition to the typical symptoms including sore throat, red and swollen tonsils, and fever, children may experience headache, stomach pain, nausea, and vomiting.

A general pediatrician can diagnose untreated strep throat in children and can help them feel better in a short time.

What Causes Strep Throat?


A bacterium called group A streptococcus or streptococcus pyogenes causes an infection in the throat known as strep throat. Streptococcal bacteria are contagious and spread from an infected person to others. When someone with the infection coughs or sneezes, small drops that contain the bacteria come out from the person's mouth and nose and can infect other people nearby who breathe in these small drops.

Risk Factors for Strep Throat

Risk Factors

Factors that increase the risk of strep throat infection are:

  • Age – strep throat occurs most commonly in school-age children around ages 5 through 15 years old.
  • Season – strep throat is more common in the winter and early spring when people spend more time indoors and are in close contact with other people who may be infected.
  • Close contact with many people – strep bacteria spreads when infected people are in close contact with others, including at home, daycare centers, schools, workplaces, public transportation, and other settings.



Strep throat is typically a mild infection, but serious complications can occur and include:

  • Scarlet fever is a strep infection that causes a bright red rash on the body, a sore throat, and a high fever.
  • Sinus infections
  • Ear infections
  • Rheumatic fever is a serious inflammatory disease that can affect the heart, joints, brain, and skin, and can develop after strep throat, scarlet fever, and strep skin infections.
  • Poststreptococcal glomerulonephritis is an infection of the kidney.
  • Poststreptococcal reactive arthritis is an inflammation of the joints.

Strep throat while pregnant

People who are pregnant are at risk for strep throat as other people. Strep throat is treated with antibiotics and a pregnant individual needs to follow the doctor's instructions regarding the dosage to avoid any complications for the mother and fetus.



There is no vaccine to prevent strep throat but there are things people can do to protect themselves and others from getting infected or infecting others. To prevent strep throat spreading, people should:

  • Cover their mouth and nose when they cough or sneeze, if possible, with a tissue. Then through the used tissue in the trash can.
  • Wash their hands often with soap and water. Use an alcohol-based hand rub if soap and water are not available.
  • Wash dishes and laundry in hot, soapy water after someone who is sick uses them.
  • Stay home from work, school, or daycare until they stopped having fever and other symptoms, and have taken antibiotics, as prescribed by the doctor, for at least 12 hours.
  • Take the prescribed medication exactly as the doctor prescribed, even if they feel better before they finish taking antibiotics for the prescribed dosage.
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Trust NewYork-Presbyterian for Strep Throat Care

At NewYork-Presbyterian, we are experienced in caring for a diverse population of patients, offering services for adults, children, adolescents, and older patients of all backgrounds. Our primary care services of family medicine doctors, internists, and pediatricians are available at more than 15 practices throughout Manhattan.

Same-day appointments can be made for urgent needs. Scheduling is easy, we offer early, late, and weekend hours, and we accept most insurance plans. Learn more about treatment for strep throat and other throat infections.

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