Screening and diagnosis

Most often, your doctor or your child's pediatrician will diagnose the cause of a sore throat on the basis of a physical exam and a throat culture. During the exam, your doctor is likely to check your throat for redness and swelling and for white streaks or pus on your tonsils. Although these signs indicate an infection, there's no accurate way to tell by looking if it's viral or bacterial.

For that reason, your doctor is likely to take a throat culture or perform a rapid strep test to check for the presence of bacteria that cause strep throat. In either case, your doctor will rub a sterile swab over the back of your throat and tonsils to get a sample of the secretions.

In the past, the only way to accurately diagnose strep throat was to have these secretions cultured in a laboratory — a procedure could take up to two days. Now, your doctor may use a rapid test that checks for bacterial infections within hours, but because rapid tests may miss a fair number of infections, your doctor may choose to have additional laboratory testing done as well.