What is the most common cause of throat pain in a relatively healthy adult?

Most Common Cause of Throat Pain in Adults

Viruses are the most common cause of throat pain in relatively healthy adults, accounting for the majority of acute pharyngitis cases. 1

Viral Etiology Predominates

• Respiratory viruses cause considerably more cases of acute pharyngitis than bacteria. 1
• The most frequent viral culprits include rhinovirus, coronavirus, adenovirus, influenza virus, parainfluenza virus, respiratory syncytial virus, and enteroviruses. 1
• Other important viral causes include Epstein-Barr virus (causing infectious mononucleosis with pharyngitis), herpes simplex virus, coxsackievirus, and cytomegalovirus. 1

Bacterial Causes Are Less Common

• Group A Streptococcus (GAS) is the most common bacterial cause but accounts for less than half of all pharyngitis cases. 1
• GAS is cultured in only 5% to 17% of adults presenting with sore throat. 2
• GAS pharyngitis is primarily a disease of children aged 5-15 years; initial attacks of rheumatic fever are rare in adults (though recurrences can occur). 1

Clinical Clues to Distinguish Viral from Bacterial

Viral pharyngitis typically presents with:

• Cough, nasal congestion (coryza), hoarseness, conjunctivitis, or diarrhea. 1
• Oropharyngeal lesions such as ulcers or vesicles. 1
• These features strongly suggest viral etiology and should not prompt testing or antibiotic treatment. 1

Bacterial (GAS) pharyngitis more commonly presents with:

• Sudden-onset sore throat, pain on swallowing, and fever (101°F-104°F). 1
• Tonsillopharyngeal exudates, tender anterior cervical lymphadenopathy, palatal petechiae, and scarlatiniform rash. 1
• However, clinical findings alone cannot reliably distinguish GAS from viral pharyngitis—even experienced clinicians achieve only 35%-50% accuracy. 1

Critical Diagnostic Principle

• Microbiological confirmation with rapid antigen detection test (RADT) or throat culture is required before diagnosing GAS pharyngitis. 1
• The modified Centor criteria (fever by history, tonsillar exudates, tender anterior cervical adenopathy, absence of cough) help identify patients at low risk who do not need testing: those with <3 criteria should receive symptomatic treatment only. 1, 3
• Patients with ≥3 Centor criteria require testing before any antibiotic prescription. 3

Common Pitfall to Avoid

• Over 60% of adults with sore throat receive antibiotic prescriptions despite most cases being viral. 1, 3
• This represents massive antibiotic overuse, as only GAS pharyngitis warrants antibiotics among common causes of pharyngitis. 1
• Even when GAS is confirmed, antibiotics provide modest benefit (shortening symptoms by only 1-2 days, with number needed to treat of 6 at day 3). 1, 3

Other Uncommon Bacterial Causes

• Groups C and G streptococci can cause pharyngitis (particularly in college students and adults) but do not cause rheumatic fever and have unclear benefit from antibiotic treatment. 1
• Fusobacterium necrophorum may account for 10%-20% of endemic pharyngitis in adolescents and can cause life-threatening Lemierre syndrome. 1
• Rare bacterial causes include Arcanobacterium haemolyticum, Neisseria gonorrhoeae, Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Corynebacterium diphtheriae. 1

Red Flags Requiring Urgent Evaluation

Patients with difficulty swallowing, drooling, neck tenderness or swelling, or unilateral tonsillar bulge should be immediately evaluated for life-threatening complications including peritonsillar abscess, retropharyngeal abscess, epiglottitis, or Lemierre syndrome rather than receiving empiric antibiotics. 1, 4