OTC Medication for Dry Hacking Cough from Postnasal Drip
For a dry hacking cough caused by postnasal drip, use a first-generation antihistamine combined with a decongestant, such as dexbrompheniramine 6 mg with pseudoephedrine 120 mg twice daily, or diphenhydramine 25-50 mg with pseudoephedrine. 1, 2
Why First-Generation Antihistamines Are Superior
The American College of Chest Physicians specifically recommends first-generation antihistamine/decongestant combinations as the most effective first-line treatment for postnasal drip cough. 1 The key advantage is their anticholinergic properties, not their antihistamine effects, which makes them superior to newer non-sedating antihistamines for this indication. 1, 2
- Older-generation antihistamines work by reducing secretions through anticholinergic mechanisms, making them more effective than newer antihistamines for non-allergic postnasal drip. 1, 2
- Recent research confirms that diphenhydramine significantly inhibits cough reflex sensitivity in patients with acute viral respiratory infections (p < 0.01). 3
- Newer-generation antihistamines (cetirizine, loratadine, fexofenadine) are ineffective for postnasal drip cough and should be avoided for this indication. 1
Specific OTC Combinations That Work
Proven effective combinations include: 1, 2
- Dexbrompheniramine 6 mg + pseudoephedrine 120 mg twice daily 1, 2
- Azatadine 1 mg + pseudoephedrine 120 mg twice daily 1, 2
- Diphenhydramine 25-50 mg + pseudoephedrine four times daily 2, 3
- Brompheniramine 12 mg twice daily (can be combined with decongestant) 2
- Chlorpheniramine 4 mg four times daily (can be combined with decongestant) 2
The decongestant component (pseudoephedrine) enhances efficacy by reducing nasal congestion and drainage. 1, 2, 4
How to Minimize Side Effects
Start with once-daily dosing at bedtime for a few days before increasing to twice-daily therapy. 1, 2 This approach minimizes daytime sedation while still providing therapeutic benefit. 1, 2
Common side effects to expect: 1, 2
- Dry mouth and transient dizziness (most common) 1
- Sedation (though this can be beneficial if cough is disrupting sleep) 5
Monitor for more serious side effects: 1, 2
- Insomnia, urinary retention, jitteriness 1
- Tachycardia and worsening hypertension (from decongestant component) 1, 2
- Increased intraocular pressure in glaucoma patients 1, 2
Expected Timeline for Improvement
Most patients will see improvement within days to 2 weeks of starting therapy. 1, 2 If no improvement occurs within this timeframe, the diagnosis should be reconsidered or alternative causes investigated. 1
Critical Pitfalls to Avoid
Do not use OTC cough and cold medications in children under 6 years of age due to potential toxicity and lack of proven efficacy. 6 Between 1969-2006, there were 123 fatalities associated with these medications in children, with most occurring in those under 2 years. 6
Avoid topical nasal decongestants (like oxymetazoline/Afrin) for more than 3 days as rhinitis medicamentosa (rebound congestion) can develop. 6
Do not use newer antihistamines (cetirizine, loratadine, fexofenadine) for postnasal drip cough—they lack the anticholinergic properties needed for efficacy. 1
Contraindications for first-generation antihistamines include: glaucoma, symptomatic prostatic hypertrophy, and cognitive impairment. 2
Contraindications for decongestants include: uncontrolled hypertension, severe coronary artery disease, and concurrent MAOI use. 2
When Intranasal Corticosteroids May Help
If the postnasal drip is due to allergic rhinitis specifically, intranasal corticosteroids can be used as first-line therapy alongside antihistamines. 6, 1 However, for non-allergic postnasal drip causing dry cough, intranasal corticosteroids are not first-line and should only be added after initial combination therapy if needed for maintenance. 7