Is Strep Throat Contagious?

  • Medical Author:
    Charles Patrick Davis, MD, PhD

    Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

  • Medical Editor: William C. Shiel Jr., MD, FACP, FACR
    William C. Shiel Jr., MD, FACP, FACR

    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

Just a Sore Throat or Strep Slideshow

What is strep throat?

  • Strep throat is a throat infection usually caused by group A streptococcal bacteria.
  • Strep throat is often accompanied by fever.
  • Strep throat is one of many causes of inflammation of the pharynx (pharyngitis), also referred to as sore throat.
  • Streptococcus spp. are the most common bacterial species to cause a sore throat
    • (15%-30% of pharyngitis in children and about 5 to 10% in adults).

Is strep throat contagious?

Strep throat is contagious for about 2-3 weeks in individuals that do not take antibiotics. However, individuals that take antibiotics for strep throat usually are no longer contagious about 24 hours after initiating antibiotic therapy. The bacteria that cause strep throat can be transmitted person-to-person by direct contact, especially from mucus droplets from the mouth and indirect contact, such as kissing and sharing utensils or drinking cups.

How do I know I have strep throat?

The incubation period for strep throat varies about 1-5 days after exposure to the bacteria. If a person develops a sore throat and a fever, they should consider the possibility they have strep throat, especially if another family member or a coworker has been diagnosed with the disease. The pattern of symptoms of strep throat are

  • sore throat,
  • fever (usually greater than 102 F or 38.8 C), and
  • whitish or yellowish pus areas on the tonsils and throat.

Some persons with strep throat also may develop

Strep throat is often accompanied by swollen lymph nodes in the neck.

Rarely, a person with strep throat  can develop a rash.

If a person has a runny nose, constant sneezing and coughing, it actually is less likely that they have strep throat.

Strep throat is diagnosed by the medical history, physical examination of the throat, and with a rapid strep test on a swab of the throat. The rapid strep test can be confirmed by a throat culture. However, most physicians will diagnose and begin treatment before a throat culture test is completed.

There are many other causes of sore throat including many viruses, bacteria other than strep, allergies, acid reflux, and tumors. Your physician can help sort through these causes of sore throat.

Strep Throat Symptoms

Streptococcus infection (strep throat ) symptoms are related to the inflammation of the throat and surrounding tissues.

Common symptoms of strep throat are

  • mild to severe sore throat
  • redness and swelling of the throat
  • white spots or patches on the tonsils, and...

How is strep throat spread?

Strep throat is easily spread by exposure to droplets from an infected person's sneeze or cough. Kissing can also cause person-to-person spread. Moreover, streptococci can survive for a while on toothbrushes, doorknobs, and other objects. If a person does not have strep throat and touches these contaminated objects, and subsequently touch their mouth or nose, they can become infected.

How do I know when I'm cured of strep throat?

Individuals can be cured of strep throat by taking antibiotics. A person taking antibiotics is no longer contagious after about 24 hours. Without taking antibiotics, persons with strep throat are infectious for about three weeks. A person is cured when symptoms are cleared.

When should I seek medical care for strep throat?

If you suspect that you have strep throat, you should contact a primary health-care professional. This is even more urgent if the person has a fever over 102 F or 38.8 C, if the person is dehydrated and has an associated headache, abdominal pain and/or nausea and vomiting. If a person develops symptoms of drooling, difficulty breathing and/or swallowing, they should immediately go to an Emergency Department. Serious strep throat can have very dangerous consequences.

The major reason to seek medical care for strep throat is that if it goes untreated or is not appropriately treated, serious complications can develop, and are

Early treatment of strep throat can help prevent these and other complications.


Khan, ZZ. et al. "Group A Streptococcal Infections." Medscape. Updated: Aug 21, 2014.

National Institute of Allergy and Infectious Diseases. "Is It Strep Throat?" Updated September 24, 2014.

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Reviewed on 10/7/2016

Khan, ZZ. et al. "Group A Streptococcal Infections." Medscape. Updated: Aug 21, 2014.

National Institute of Allergy and Infectious Diseases. "Is It Strep Throat?" Updated September 24, 2014.

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