Causes of Laryngitis
The vast majority of laryngitis cases are caused by acute viral upper respiratory infections, particularly parainfluenza, rhinovirus, influenza, and adenovirus 1.
Acute Laryngitis (Most Common)
Viral Causes (Primary Etiology)
- Parainfluenza viruses (most common) 2
- Rhinovirus
- Influenza virus
- Adenovirus
These viral infections cause direct inflammation of the vocal cords or irritation from postnasal drainage 3. The condition is self-limited, with symptomatic improvement typically occurring within 7-10 days regardless of treatment 1.
Bacterial Causes (Rare, Specific Circumstances)
Bacterial laryngitis should only be considered in select situations 1:
Immunocompromised patients:
- Laryngeal tuberculosis (renal transplant recipients, HIV patients)
- Atypical mycobacterial infections (patients on inhaled steroids)
Specific bacterial infections:
- Pertussis (waning immunity in adolescents/adults)
- Bacterial laryngotracheitis from S. aureus (presents with mucosal crusting, cough, stridor, increased work of breathing)
- Acute epiglottitis (presents with systemic symptoms and respiratory distress) 3
Critical caveat: Diagnosis must be established before initiating antibiotic therapy 1. Empiric antibiotics are not indicated and cause harm through side effects, costs, and antibiotic resistance 1.
Chronic Laryngitis (>3 Weeks Duration)
Vocal Overuse/Trauma
- Occupational voice users: singers, teachers, chemical workers 3
- Chronic overloading of speech organs (16.5% of professional voice users) 4
- Results in nodules or polyps from stress on vocal cords 3
Inflammatory/Irritant Causes
- Gastroesophageal/laryngopharyngeal reflux disease (LPRD) - regurgitation of acidic gastric content causing hyperemia and edema 5, 4
- Smoking (major factor) 4
- Inhaled corticosteroids - causes laryngeal candidiasis and chronic inflammation 6, 4
- Chemical exposure 3
Infectious Causes
- Fungal laryngitis (laryngeal candidiasis) - often related to inhaled corticosteroids or antibiotic use 1, 6
- Chronic bacterial laryngitis - difficult to differentiate from sicca laryngitis; common pathogens include MSSA (40.3%), MRSA (25.6%), and Klebsiella (33.3%) 7
Systemic/Autoimmune Conditions
- Chronic tonsillitis 4
- Bronchial asthma 4
- Diabetes mellitus 4, 7
- Systemic lupus erythematosus 1
- Sarcoidosis 1
- Granulomatosis with polyangiitis 1
Specific Forms
- Ulcerative laryngitis - rare condition associated with prolonged cough, causing bilateral symmetrical ulcerative defects in middle third of vocal folds 8
- Sicca laryngitis - overlaps with chronic bacterial laryngitis, difficult to differentiate 7
Key Clinical Distinctions
Acute occupational laryngitis in otherwise healthy professional voice users (36.9%) develops from overloading speech organs, while viral/bacterial laryngitis (63.1%) is preceded by acute respiratory symptoms 4.
Common pitfall: The multifactorial nature of chronic laryngitis (smoking, inhaled corticosteroids, reflux, diabetes) makes single-cause attribution inappropriate 6. Address all contributing factors simultaneously for optimal outcomes.