What is the drug of choice for an allergic cough?

First-Line Drug Therapy for Allergic Cough

For allergic cough, a first-generation antihistamine-decongestant combination is the first-line drug of choice, followed by intranasal corticosteroids if symptoms persist. 1

Treatment Algorithm for Allergic Cough

First-Line Therapy

1. First-generation antihistamine-decongestant combination
   • Expected to show improvement within days to 1-2 weeks
   • Complete resolution may take several weeks
   • Examples: dexbrompheniramine maleate plus sustained-release pseudoephedrine
   • Maximum duration: 3 weeks
   • Caution: Sedation, dry mouth, urinary retention; use with caution in patients with glaucoma, prostatic hypertrophy, or hypertension 1

Second-Line Therapy (for partial response)

1. Intranasal corticosteroids
   • Examples: fluticasone propionate nasal spray
   • Dosage: 1-2 sprays in each nostril once or twice daily
   • Duration: Initial 1-month trial, may continue for up to 3 months if effective 1
   • Significantly improves daytime cough severity compared to placebo (P = 0.049) 2
   • Most effective medication for treating allergic rhinitis 3

Alternative or Adjunctive Therapies

1. Second-generation antihistamines

   • Loratadine, desloratadine, cetirizine, fexofenadine
   • Better safety profile than first-generation antihistamines 4
   • Loratadine significantly reduces cough in patients with nasal disease and unexplained chronic cough 5
   • Well-tolerated in young children 3

2. Nasal anticholinergics

   • Ipratropium bromide nasal spray for rhinorrhea-predominant symptoms 1
   • Suppresses subjective measures of cough in patients with URI or chronic bronchitis 3

3. Leukotriene receptor antagonists

   • Montelukast may be considered as adjunctive therapy 1, 6
   • Particularly useful in patients with coexisting asthma 6

Important Considerations

Efficacy Assessment

• Evaluate response after 3-5 days of treatment
• If minimal improvement after 10-14 days, consider changing therapy
• For partial response, continue treatment for another 10-14 days 1

Special Populations

• Children under 6 years: First-generation antihistamine/decongestant combinations are not recommended due to safety concerns 1
• Elderly patients: Monitor for dehydration and consider nutritional support if oral intake is poor 1

Common Pitfalls to Avoid

1. Overuse of antibiotics

   • Most cases of rhinosinusitis are viral, with only 0.5% to 2.0% having bacterial etiology 1
   • Relying on mucus color to dictate antibiotic use is not recommended

2. Prolonged use of first-generation antihistamines

   • Can cause significant sedation and cognitive impairment
   • May worsen sleep architecture 4

3. Prolonged use of topical decongestants

   • Not recommended for continuous use due to potential development of rhinitis medicamentosa
   • Development of rhinitis medicamentosa is highly variable; may develop within 3 days of use 3

Non-Pharmacological Approaches

• Adequate hydration
• Warm facial packs
• Sleeping with head elevated
• Avoiding irritants (cigarette smoke, pollution, allergens) 1

Coexisting Conditions

If allergic cough persists despite appropriate treatment, consider:

• Asthma
• Gastroesophageal reflux disease (GERD)
• Upper Airway Cough Syndrome (UACS)

These three conditions account for 90% of chronic cough cases and often coexist, requiring treatment of all causes for cough resolution 1.