What are the common causes of throat clearing?

Common Causes of Throat Clearing

The most common cause of throat clearing is Upper Airway Cough Syndrome (UACS), previously called postnasal drip syndrome, which accounts for the majority of cases either alone or in combination with other conditions, and should be treated empirically with first-generation antihistamine/decongestant combinations even when patients lack obvious upper respiratory symptoms. 1

Primary Causes

Upper Airway Cough Syndrome (UACS)

• UACS is the leading cause of chronic throat clearing, resulting from postnasal drainage that triggers the sensation of mucus in the throat 2, 1
• The underlying conditions causing UACS include:
  • Allergic rhinitis - characterized by nasal itching, sneezing, clear rhinorrhea, and seasonal patterns 1
  • Perennial nonallergic rhinitis (vasomotor rhinitis) 1
  • Chronic sinusitis - accounts for approximately 31% of postnasal drip cases 3
  • Postinfectious rhinitis following viral upper respiratory infections 2
  • Chronic rhinitis - represents about 22% of cases 3

Viral Upper Respiratory Infections (Common Cold)

• The common cold is the single most common cause of acute throat clearing and cough, with over 200 viruses capable of causing this syndrome 2, 4
• Viral infections cause vasodilation and hypersecretion, producing the clinical syndrome of nasal discharge, postnasal drip, throat clearing, and cough 2
• Rhinoviruses account for 30-80% of common colds, coronaviruses cause approximately 15%, and respiratory syncytial virus causes 10-15% 4
• The mechanism involves direct irritation of upper airway structures and inflammatory mediators that increase sensitivity of afferent sensory nerves 2

Allergic Rhinitis

• Allergic rhinitis causes throat clearing through postnasal drainage, affecting approximately 28% of patients with postnasal drip syndrome 3
• Distinguishing features include nasal itching, sneezing, clear rhinorrhea, and pale nasal mucosa 1
• Diagnosis should be confirmed with specific IgE testing (skin or blood) when uncertain or when empiric treatment fails 1

Anatomic Abnormalities

• Nasal septal deviation and turbinate hypertrophy can lead to postnasal drip and throat clearing 2
• Adenoidal hypertrophy is the most common acquired anatomic cause in infants and children 2
• Nasal polyps occur in 2-4% of the population and may cause throat clearing, though allergy as a direct cause has not been established 2

Ciliary Dysfunction

• Primary ciliary dyskinesia (PCD) is a rare genetic disorder causing ineffective mucociliary clearance, leading to chronic throat clearing 2
• Secondary ciliary dysfunction is more common and results from acute or chronic infections, multiple sinus surgeries, or irritant rhinitis 2
• After infection, resolution of secondary ciliary dysfunction may require weeks 2

Critical Clinical Pearls

Diagnostic Pitfalls to Avoid

• Approximately 20% of patients with UACS have "silent" postnasal drip - they are completely unaware of drainage yet still respond to treatment, so do not rely on patient awareness of postnasal drip 1
• Pharyngeal erythema is non-specific and should not be used alone to diagnose laryngopharyngeal reflux 1
• Throat clearing is unlikely to be GERD-related - research shows low probability of objective association between throat clearing and gastroesophageal reflux, especially when it is the only symptom 5
• Consider aspiration risk in patients with throat clearing during or after swallowing, particularly in elderly or those with neurologic disease - evaluate with water swallow test 1

Multiple Simultaneous Causes

• UACS, allergic rhinitis, asthma, and GERD frequently coexist, and treating all identified conditions simultaneously is crucial for resolution 1
• In studies of acute cough, approximately one-third of patients diagnosed with "acute bronchitis" actually had acute asthma 2

Treatment Algorithm

First-Line Empiric Therapy

1. Initiate first-generation antihistamine/decongestant combination for 2-4 weeks as first-line therapy for UACS, even without obvious upper respiratory symptoms 1

   • First-generation antihistamines are superior to second-generation due to anticholinergic effects that reduce secretions 1
   • Treatment with antihistamine/decongestant (pseudoephedrine plus brompheniramine) leads to more rapid improvement in throat clearing and postnasal drip compared to placebo 2

2. If allergic rhinitis is suspected, add intranasal corticosteroids as primary therapy 1

   • Consider oral antihistamines as adjunctive therapy 1
   • Confirm diagnosis with specific IgE testing if necessary 1

3. For viral upper respiratory infections, treat with first-generation antihistamine plus decongestant combinations, which provide significant symptom relief in 1 in 4 patients 4

   • Intranasal ipratropium bromide is effective for rhinorrhea 4
   • Zinc (acetate or gluconate) reduces symptom duration if started within 24 hours 4

When to Escalate Care

• If no response after 2-4 weeks of empiric therapy, consider specific IgE testing for allergic rhinitis if exposure patterns suggest allergy 1
• Evaluate for aspiration in high-risk patients using water swallow test, with referral for formal evaluation if positive 1
• Refer to otolaryngology if symptoms are persistent, unexplainable, or associated with unilateral obstruction, bleeding, hyposmia/anosmia, pain, or otalgia (warning signs of tumor) 2

Important Warnings

• Never prescribe antibiotics for the common cold - they provide no benefit and increase risk of adverse effects 4
• Avoid prolonged use of topical decongestants (>3-5 days) to prevent rhinitis medicamentosa, which causes rebound congestion 1
• Do not assume GERD is the cause - throat clearing has low probability of objective association with reflux, and empiric proton pump inhibitor therapy is not indicated without other reflux symptoms 5