What are the possible non‑infectious causes of a sore throat persisting for several weeks?

Non-Infectious Causes of Persistent Sore Throat

When a sore throat persists beyond 2–3 weeks without evidence of active infection, the most common non-infectious causes are gastroesophageal reflux disease (GERD), upper airway cough syndrome (post-nasal drip), chronic irritant exposure (smoking, environmental pollutants, vocal strain), and—critically—malignancy, which must be excluded in any persistent case. 1

Duration That Defines "Persistent"

• Viral pharyngitis typically resolves within 7 days, and even streptococcal pharyngitis clears within 3–4 days without treatment 1, 2
• Post-viral cough may persist 3–8 weeks after upper respiratory infection, but the sore throat component should not last this long 1
• Any sore throat lasting beyond 3 weeks warrants mandatory evaluation because this exceeds the expected course of benign viral infections 1

Primary Non-Infectious Causes

Gastroesophageal Reflux Disease (GERD)

• GERD is a leading cause of chronic throat symptoms in specialty clinics 1
• Effective management requires intensive acid suppression with a proton-pump inhibitor for at least 2 months 1
• This is one of the most treatable causes and should be addressed early in persistent cases 1

Upper Airway Cough Syndrome (UACS)

• Formerly termed "post-nasal drip syndrome" 1
• UACS is one of the most common causes of chronic cough and throat irritation in specialist settings 1
• Often results from chronic rhinosinusitis causing persistent post-nasal drainage 1

Chronic Irritant Exposure

• Persistent throat symptoms arise from smoking, environmental exposures (indoor/outdoor air pollutants), or vocal strain 1, 3
• Physico-chemical factors include shouting, medications, temperature and humidity changes, and occupational irritants 3
• Neurogenic inflammation appears to be the underlying pathophysiology 3

Eosinophilic Bronchitis

• Can present with ongoing throat clearing and irritation 1
• Should be considered when other common causes have been excluded 1

Chronic Infectious Causes Mimicking Non-Infectious Disease

Group A Streptococcus Carrier State

• Chronic carriers harbor the organism without active infection, obtain no benefit from antibiotics, and have a low risk of complications 1
• Up to 20% of asymptomatic adolescents may be GAS carriers during winter/spring 2
• Repeated antibiotic courses provide no clinical benefit 1

Pertussis (Bordetella pertussis)

• Pertussis produces ongoing cough and throat irritation; approximately 10% of chronic-cough patients have positive nasal swab for Bordetella 1
• Should be considered when paroxysmal cough accompanies persistent throat symptoms 4

Fusobacterium necrophorum

• Implicated in 10–20% of endemic pharyngitis cases in adolescents and may progress to Lemierre syndrome 1, 2
• Persistent high fever with severe pharyngitis in adolescents/young adults warrants consideration 1

Groups C and G Streptococci

• Can cause severe or recurrent pharyngitis and may lead to complications such as reactive arthritis and glomerulonephritis 1, 4
• Case reports describe subdural empyema and toxic shock-like syndrome 4

Malignancy—The Critical Exclusion

• Cough is the fourth most common presenting symptom of lung cancer, and lung malignancy can manifest as a persistent throat complaint 1
• Laryngeal cancer delays beyond 3 months lead to higher disease stage and worse prognosis 1
• Chest radiography is mandatory when evaluating chronic throat symptoms to exclude malignancy and other pulmonary pathology 1

Diagnostic Evaluation Algorithm

Immediate Red Flags Requiring Urgent Assessment

• New-onset dysphagia, drooling, or neck tenderness/swelling requires urgent evaluation for peritonsillar abscess, retropharyngeal abscess, or epiglottitis 1, 2
• Unilateral tonsillar swelling with uvular deviation suggests peritonsillar abscess 2
• "Hot-potato" voice indicates deep space infection 2

Mandatory Workup for Persistent Cases (>3 Weeks)

• Chest radiography to exclude malignancy and pulmonary pathology 1
• Spirometry to identify underlying airway disease 1
• Laryngoscopy (transnasal flexible fiberoptic scope) is necessary to directly examine the larynx and pharynx 1
• The American Academy of Otolaryngology states symptoms persisting beyond 3 months require laryngoscopy, but earlier evaluation is appropriate when clinical suspicion exists 1

Trial of Empiric Therapy Before Invasive Testing

• If no red flags present, consider 2-month trial of proton-pump inhibitor for presumed GERD 1
• Treat chronic rhinosinusitis and UACS with appropriate medical management 1
• Eliminate irritant exposures (smoking cessation, environmental modifications) 3

Common Pitfalls to Avoid

• Assuming all persistent sore throats are "slow to resolve" viral infections delays diagnosis of serious conditions like cancer 1
• More than 60% of adults presenting with sore throat receive antibiotics that are not indicated 1, 2
• Continuing to prescribe antibiotics without proper evaluation is inappropriate, especially in chronic streptococcal carriers 1
• Waiting the full 3 months before seeking evaluation is not recommended; a 1-month duration already exceeds typical viral illness and warrants earlier assessment 1
• Failing to obtain chest radiography in persistent cases misses the opportunity for early cancer detection 1