Treatment for Nocturnal Cough from Postnasal Drip
Start with a first-generation antihistamine/decongestant combination taken at bedtime, specifically dexbrompheniramine 6 mg plus pseudoephedrine 120 mg (sustained-release) twice daily, or azatadine 1 mg plus pseudoephedrine 120 mg (sustained-release) twice daily. 1, 2
Why First-Generation Antihistamines Work Best
First-generation antihistamines are superior to newer non-sedating antihistamines because they work through anticholinergic properties that reduce nasal secretions, not through antihistamine effects alone. 1, 2
Newer-generation antihistamines (like loratadine, fexofenadine, cetirizine) are ineffective for postnasal drip cough because they lack anticholinergic activity. 1, 2
The combination with a decongestant (pseudoephedrine) has proven efficacy in randomized controlled trials specifically for upper airway cough syndrome. 1, 2
Dosing Strategy to Minimize Side Effects
Start with once-daily dosing at bedtime for a few days before increasing to twice-daily therapy to minimize daytime sedation. 1, 2
This approach is particularly useful for nocturnal cough, as the sedating effect becomes therapeutic rather than problematic. 3
Most patients see improvement within days to 2 weeks of starting treatment. 1
Alternative First-Generation Antihistamine Options
If the recommended combinations are unavailable, other effective first-generation antihistamines include: 2
- Chlorpheniramine 4 mg four times daily
- Diphenhydramine 25-50 mg four times daily
- Brompheniramine 12 mg twice daily
When to Add Intranasal Corticosteroids
If symptoms persist after 1-2 weeks of antihistamine/decongestant therapy, add intranasal fluticasone 100-200 mcg daily for a 1-month trial. 1
This is particularly important if there's any suspicion of allergic rhinitis as the underlying cause. 1
Important Side Effects to Monitor
Common side effects include: 1, 2
- Dry mouth and transient dizziness
- Sedation (minimized by bedtime dosing)
More serious side effects requiring monitoring: 1
- Urinary retention (avoid in patients with prostatic hypertrophy)
- Tachycardia and worsening hypertension from the decongestant component
- Increased intraocular pressure in glaucoma patients
- Insomnia and jitteriness
Critical Pitfalls to Avoid
Do not use newer antihistamines like cetirizine or loratadine—they are ineffective for postnasal drip cough. 1, 4
Do not assume visible postnasal drainage is required for diagnosis—approximately 20% of patients have "silent" postnasal drip with no obvious symptoms yet still respond to treatment. 3, 1
Do not use over-the-counter cough suppressants (like dextromethorphan alone) as first-line therapy—they are not effective for postnasal drip cough. 3, 5
If Treatment Fails After 2 Weeks
Consider gastroesophageal reflux disease (GERD) as an alternative or coexisting cause, as it can mimic postnasal drip symptoms. 3, 1
Initiate empiric proton pump inhibitor therapy (omeprazole 20-40 mg twice daily before meals) for at least 8 weeks if GERD is suspected. 1
Evaluate for asthma or non-asthmatic eosinophilic bronchitis as alternative diagnoses. 1