How are viral and bacterial causes of pharyngitis (sore throat) differentiated?

Updated: May 06, 2020
  • Author: John R Acerra, MD; Chief Editor: Jeter (Jay) Pritchard Taylor, III, MD  more...
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It is difficult to distinguish viral and bacterial causes of pharyngitis on the basis of history and physical examination alone. Nevertheless, the following factors may help rule out or diagnose GAS pharyngitis:

  • GAS infection is most common in children aged 4-7 years

  • Sudden onset is consistent with GAS pharyngitis; pharyngitis after several days of coughing or rhinorrhea is more consistent with a viral etiology

  • Contact with others who have GAS or rheumatic fever with symptoms consistent with GAS raises the likelihood of GAS pharyngitis

  • Headache is consistent with GAS infection

  • Cough is not usually associated with GAS infection

  • Vomiting is associated with GAS infection, though not exclusively so

  • Recent orogenital contact suggests possible gonococcal pharyngitis

  • A history of rheumatic fever is important

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