Viruses are the most common cause of pharyngitis in adults. Group-A beta- hemolytic streptococci (Spyogenes) accounts for 50% of pharyngitis cases in children but only 10% of cases in adults. Centor criteria (fever, absence of cough, tonsillar exudate, and tender anterior cervical lymphadenopathy) are widely used to identify patients at risk for group-A streptococcal pharyngitis. Patients with two or three criteria should have a positive rapid streptococcal antigen test or positive throat culture before being given antibiotics. A negative rapid streptococcal antigen test needs to be confirmed by a throat culture. Patients meeting all four Centor criteria should also have either of the previously described confirmatory tests but may be treated empirically while awaiting results. A 10-day course of oral penicillin continues to be the treatment of choice for streptococcal pharyngitis. A 5-day course of azithromycin can be used in penicillin-allergic patients.Trismus, hoarseness, and neck swelling are concerning for more serious infections such as epiglottitis. Runny nose, cough, and myalgia suggest a viral illness such as the common cold.