Most sore throats are caused by viruses. These are often mild and go away in a few days. But strep throat is more serious. It's a throat infection caused by bacteria. Strep throat mainly affects children between 6 and 12 years of age, but can affect adults too. When it isn't treated, it can lead to serious problems including rheumatic fever (an inflammation of the joints and heart) and kidney damage.

Call 911 for trouble breathing or swallowing. Call the doctor about other symptoms of strep throat, such as:
Throat pain, especially when swallowing
Red, swollen tonsils
Fever
Stomachache; sometimes, vomiting in younger children
Pus in the back of the throat
An examination will be done and questions asked about the patient's medical history.
The patient's tonsils will be examined. A sample of fluid may be taken from the back of the throat using a soft swab. The sample can be checked right away for the bacteria that cause strep throat. Another sample may also be sent to a lab for testing.
An antibiotic may be prescribed to kill the bacteria. The patient must take all the medication, even if he or she starts to feel better. (Note that antibiotics will not help a viral throat infection.)
If swallowing is very painful, painkilling medication may also be prescribed.
Call your doctor if the patient has finished the treatment for strep throat and has:
A fever
Joint pain or swelling
Rash