How Long Is Strep Throat Contagious?

Collecting a throat culture.
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Strep throat is contagious for two to five days before you even start to experience symptoms. During this time, you may unknowingly share your germs with someone else.

The duration of being contagious is dependent upon when you start taking antibiotics (strep throat, also known as Group A Streptococcus (GAS), is caused by the bacteria streptococcus pyogenes, which bacteria can help kill). Despite already having been contagious, once you start to have symptoms (such as a sore throat) and suspect you may have strep throat, you should start taking precautions not to infect those around you.


If your sore throat is accompanied with a runny nose, pink eye, hoarseness, or diarrhea, you likely do not have strep throat and your doctor will not test you for strep throat. In this case you likely have a viral infection and will not need antibiotics.

However, you will need to be tested for strep throat if you do not have signs of viral infection and have the following symptoms:

  • sore throat
  • fever
  • enlarged lymph nodes
  • abdominal pain
  • small red or purple spots on the roof of your mouth
  • redness around your tonsils
  • white patches on your tonsils

Testing and Treatment

Strep throat is most common in children between 5 to 15 years old and only makes up 5 to 10 percent of sore throat cases in adults. This is why your doctor will not just start giving you antibiotics. It is important to help prevent development of "super bugs," or antibiotic resistant bacteria, so your doctor won't give antibiotics until he or she is sure you need them.

To test for strep throat your doctor will need to perform a strep test. If your strep test is negative and your doctor suspects a viral infection, you will not need antibiotics. However if you test positive for strep throat, you can easily be treated with penicillin or amoxicillin being the antibiotic of choice.

Penicillin is often given as a shot in a muscle, but it can also be given orally twice a day over 10 days. Amoxicillin is usually dosed once a day in children and twice a day in adults.

If you have an allergy to penicillin, then the next best type of antibiotic are from the cephalosporin class: Keflex, clindamycin, clarithromycin, or Zithromax. These antibiotics range from once or twice a day dosing over 5 to 10 days. If you have been diagnosed with recurrent strep throat, then you will be started on Augmentin or Omnicef, as these cover a broader range of bacteria.

How Long Will I Be Contagious?

If you are diagnosed with strep, you will stop being contagious approximately 24 hours after starting an antibiotic. Antibiotics should help alleviate your symptoms within one or two days, although in some people the symptoms may last up to a week. Without treatment, strep throat generally resolves on its own in about a week. If you don't have any reduction in fever or other symptoms within 48 hours of starting antibiotics, contact your physician.

If you are on an antibiotic and you do not have a fever the night before returning to school or work, you will not be contagious. If you continue to have a fever the night before, you will not want to return to school or work, as you will likely spread strep to others around you.

Preventing Others From Getting Sick

You may not always be able to avoid others while having strep throat. You can count on being contagious if you still have a fever or have not been on antibiotics for more than 24 hours. If you think you are contagious and will be around others, you can try these tips to reduce your risk of getting them sick as well.

  • Strict and frequent hand washing (wash for about the length of the alphabet song) with soap/water or use a hand sanitizer and let air dry.
  • Cover your mouth when you cough or sneeze. You can use a Kleenex, napkin, or sleeve. Do not cover your mouth with your hands. If you do cover your mouth with your hands, wash them immediately.
  • Do not share eating utensils or drinking glasses with anyone.

Avoiding people altogether is best, however following the above tips can drastically reduce the risk of sharing strep throat with others. Strep throat is passed through droplets that are sneezed, coughed or shared in other ways. Touching contaminated surfaces and then touching your mouth, kissing, or sharing silverware or drinking glasses will increase the risk of spreading strep throat to someone else. Children in the same household have a 50 percent chance of sharing strep throat with their siblings.

Potential Complications 

Treatment with antibiotics should begin within nine days of the onset of your symptoms. If you do not treat your strep throat with antibiotics, or you do not take all the pills as prescribed by your doctor, you will increase your risk for developing complications like recurrent strep or rheumatic heart disease.

If you do not complete your full course of antibiotics, you also increase the risk of creating resistant strains of bacteria, known as superbugs, that are more difficult to treat; this is a public health concern.

A Word From Verywell

In general, you should always practice good hygiene, as described in the prevention section, as you will often be contagious with strep before you feel sick. However, once you determine that you are sick, seeking medical attention to determine whether or not you have strep can help you return to school or work sooner and prevent future complications. Make sure that you complete the full course of antibiotics as your doctor prescribes.


Kalra, MG, Higgin, KE & Perez, ED. (2016). Common Questions About Streptococcal Pharyngitis. American Family Physician, 94:1, 24-31

Medline Plus. Strep Throat.

Schwartz, R.H. (2016). Is it okay to return to school the day after 1 strep throat treatment? Contemp Pediatr. 33 (2): 11-12. (2p)

The Merck Manuals Online Medical Library. Streptococcal Infections.

Wald, ER. (2016). Group A streptococcal tonsillopharyngitis in children and adolescents: Clinical features and diagnosis. (Subscription Required)