Many different factors can cause a sore throat. Viral infections are the most common source of sore throats in young children. These include colds, influenza, measles, mumps, chickenpox, croup and mononucleosis.

Children may become infected with viruses when breathing in particles from someone who is infected, or touching an object contaminated with germs, then transferring those germs into the body by touching the eyes, mouth or nose.

Bacterial infections also can lead to sore throats. For instance, bacterium called group A Streptococcus pyogenes causes strep throat.

If a bacterial infection is believed to be the cause, a physician may perform a throat culture. In this test, a long cotton swab is used to wipe the back of the throat. The swab is wiped onto a special culture dish, which is sent to a laboratory for analysis. An expert examines the sample to see if bacteria are growing there, and to determine the type of the infection. A rapid version of this test may be performed by some physicians, which can identify strep throat in minutes.

Other causes of sore throats include:

• Allergies or hay fever. Pollens, molds, pet dander and other allergens can trigger symptoms in some children that may include sore throat.
  
  
• Breathing in polluted or dry air. Outdoor air pollution and indoor air pollution (such as from tobacco smoke) often cause a child’s throat to feel sore or scratchy. Dry air (especially heated air during winter) can cause soreness in the throat, particularly upon waking.
  
  
• Smoking and other irritants. Older children who smoke or use alcohol may experience a sore throat. Spicy foods also can inflame the throat.
  
  
• Straining throat muscles. Children who yell for long periods of time (such as cheering at a sporting event) may experience soreness.
  
  
• Chronic sinus infections. Drainage from infected sinuses can trigger an infection of the throat, which in turn leads to soreness.
  
  
• Gastroesophageal reflux disease (GERD). This disease causes stomach acid to back up into the food pipe (esophagus) and may be accompanied by a sore throat. GERD is rare in children.
  
  
• Tumors. Growths that develop on the throat, tongue and voice box can sometimes lead to a sore throat.