What is the treatment for a chronic cough caused by postnasal drip?

Treatment for Chronic Cough from Postnasal Drip

Start with a first-generation antihistamine plus decongestant combination (such as dexbrompheniramine with sustained-release pseudoephedrine or azatadine with sustained-release pseudoephedrine) as your first-line therapy for chronic cough caused by postnasal drip, now termed Upper Airway Cough Syndrome (UACS). 1, 2

First-Line Treatment Algorithm

For Non-Allergic Rhinitis-Related Postnasal Drip

• Begin with first-generation antihistamine/decongestant combinations as these are the most effective initial therapy, superior to newer non-sedating antihistamines due to their anticholinergic properties that directly address the cough mechanism 1, 2
• Specific effective combinations include:
  • Dexbrompheniramine maleate plus sustained-release pseudoephedrine sulfate 1, 2
  • Azatadine maleate plus sustained-release pseudoephedrine sulfate 1, 2
• Treat for a minimum of 3 weeks for chronic cases, though most patients improve within days to 2 weeks 1, 2
• To minimize sedation, start with once-daily dosing at bedtime before advancing to twice-daily therapy 1, 2

For Allergic Rhinitis-Related Postnasal Drip

• Start combination therapy immediately: first-generation antihistamine/decongestant PLUS intranasal corticosteroid 3, 2
• The first-generation antihistamine is critical for the cough component, unlike newer antihistamines which are ineffective for UACS-induced cough 3, 2
• Intranasal corticosteroids (fluticasone 100-200 mcg daily) should be given for a 1-month trial 1, 2
• Alternative first-line options include nasal cromolyn or leukotriene receptor antagonists (montelukast 10 mg daily), though these are less effective than intranasal corticosteroids 1, 3

Second-Line and Adjunctive Therapies

If No Response After 1-2 Weeks

• Add ipratropium bromide nasal spray (42 mcg per spray, 2 sprays per nostril 4 times daily) for patients who don't respond to antihistamine/decongestant combinations or have contraindications to decongestants 1, 2
• This provides anticholinergic drying effects without systemic cardiovascular side effects 2

For Moderate-to-Severe Allergic Rhinitis

• Consider combination intranasal fluticasone propionate plus intranasal azelastine, which provides 40% superior symptom reduction compared to monotherapy 3
• This combination is particularly effective for patients with inadequate response to single-agent therapy 3

Adjunctive Nasal Saline Irrigation

• Nasal saline irrigation is more effective than saline spray because it better expels secretions through mechanical removal of mucus and enhanced ciliary activity 2
• Longer treatment duration (mean 7.5 months) shows better results than shorter courses 2

Treatment for Chronic Sinusitis-Related Postnasal Drip

• Initial regimen requires:
  • Minimum 3 weeks of antibiotics effective against H. influenzae, mouth anaerobes, and S. pneumoniae 1
  • 3 weeks of oral antihistamine/decongestant 1
  • 5 days of nasal decongestant (maximum duration to avoid rhinitis medicamentosa) 1
• After cough resolves, continue intranasal corticosteroids for 3 months to maintain symptom control and prevent recurrence 3

Critical Pitfalls and Caveats

Medication Selection Errors

• Never use newer-generation antihistamines as monotherapy for non-allergic UACS—they are ineffective for this indication despite working for allergic rhinitis 1, 2
• Never use topical nasal decongestants (oxymetazoline, xylometazoline) for more than 3-5 consecutive days due to risk of rhinitis medicamentosa (rebound congestion) 1, 2
• Guaifenesin has limited evidence for efficacy despite its FDA indication for loosening phlegm 1

Timing and Duration Mistakes

• Do not discontinue intranasal corticosteroids prematurely—for chronic sinusitis-related UACS, the 3-month continuation after cough resolution is critical for preventing recurrence 3
• For allergic rhinitis, intranasal corticosteroids can be started immediately alongside antihistamines, unlike non-allergic UACS where they may be delayed 3

Diagnostic Considerations

• Approximately 20% of patients have "silent" postnasal drip with no obvious symptoms yet still respond to treatment—don't rule out UACS based on absence of typical symptoms 1, 2
• The diagnosis is confirmed by response to specific therapy, not by symptoms or physical findings alone 2
• Cobblestoning of the posterior pharyngeal wall is a hallmark physical finding when present 2

Side Effects to Monitor

Common Side Effects

• Dry mouth and transient dizziness from first-generation antihistamines 1, 2
• Insomnia, irritability, palpitations from decongestants 1, 2

Serious Side Effects Requiring Monitoring

• Monitor blood pressure after initiating decongestant therapy, as they can worsen hypertension and cause tachycardia 2
• Urinary retention, jitteriness, and increased intraocular pressure in glaucoma patients from first-generation antihistamines 1, 2
• Use decongestants with extreme caution in patients with cardiovascular disease 2

When to Reassess for Other Causes

• If symptoms persist despite adequate upper airway treatment for 2 weeks, proceed with sequential evaluation for other common causes 2:
  • Asthma/non-asthmatic eosinophilic bronchitis (consider bronchial provocation testing if spirometry is normal) 2
  • Gastroesophageal reflux disease (initiate empiric proton pump inhibitor therapy: omeprazole 20-40 mg twice daily before meals for at least 8 weeks) 2
• Maintain all partially effective treatments rather than discontinuing them prematurely, as UACS, asthma, and GERD together account for approximately 90% of chronic cough cases 2
• UACS can be confused with GERD, as both can present with throat symptoms 1, 2