What is the drug of choice for an allergic cough?

Drug of Choice for Allergic Cough

For allergic cough specifically due to allergic rhinitis, nasal corticosteroids, oral antihistamines, and/or nasal cromolyn are the initial drug choices, with nasal corticosteroids and second-generation (nonsedating) antihistamines being preferred first-line agents. 1

First-Line Treatment Options

Nasal Corticosteroids (Preferred)

• Nasal corticosteroids are among the initial drug choices for allergic rhinitis-induced cough and have been shown to effectively reduce both nasal inflammation and associated cough symptoms 1
• Mometasone furoate nasal spray significantly improved daytime cough severity scores (P = 0.049) and overall daytime symptom scores (P = 0.005) in patients with seasonal allergic rhinitis-associated cough 2
• These agents work by reducing nasal inflammation that triggers the upper airway cough reflex 2

Second-Generation (Nonsedating) Antihistamines

• Nonsedating antihistamines (loratadine, desloratadine, cetirizine, fexofenadine) are likely to be more effective in treating allergic rhinitis-associated cough than in nonallergic rhinitis 1
• These agents are preferred over first-generation antihistamines because they produce less sedation and impairment while maintaining efficacy 3
• Loratadine 10 mg daily significantly reduced cough frequency (P < 0.05) and cough intensity (P < 0.01) in patients with allergic rhinoconjunctivitis and cough 4

Nasal Cromolyn

• Nasal cromolyn is listed as one of the initial drug choices for allergic rhinitis-induced cough based on controlled studies 1

Alternative and Adjunctive Options

Oral Leukotriene Inhibitors

• Leukotriene blockers (such as montelukast) have been shown to decrease symptoms of allergic rhinitis and may be considered as an alternative or adjunctive therapy 1
• Montelukast works by blocking the CysLT1 receptor, inhibiting the physiologic actions of leukotriene D4 5

First-Generation Antihistamines Plus Decongestant

• First-generation antihistamines combined with decongestants are NOT the preferred choice for allergic rhinitis-associated cough because the anticholinergic effect that makes them useful in nonallergic rhinitis is less relevant when histamine is the primary mediator 1
• However, combinations like dexbrompheniramine 6 mg bid or azatadine 1 mg bid plus pseudoephedrine 120 mg bid may be considered if second-generation agents fail 1

Treatment Algorithm for Allergic Cough

1. Confirm allergic etiology: Positive skin test to allergens, seasonal or perennial pattern, associated rhinitis symptoms 1

2. Initiate first-line therapy with either:

   • Nasal corticosteroid spray (e.g., mometasone furoate) 2, OR
   • Second-generation oral antihistamine (e.g., loratadine 10 mg daily, cetirizine, fexofenadine) 3, 4, OR
   • Nasal cromolyn 1

3. Assess response within days to 2 weeks 1

4. If inadequate response, consider:

   • Adding or switching to combination therapy (nasal corticosteroid + oral antihistamine) 1
   • Adding oral leukotriene inhibitor 1

5. If still inadequate, consider first-generation antihistamine/decongestant combination 1

Critical Pitfalls to Avoid

• Do not use first-generation antihistamines as first-line for allergic cough – they cause sedation, impairment, and worsen sleep architecture without offering superior efficacy for histamine-mediated conditions 3
• Avoid topical decongestants for prolonged use – use only short-term to prevent rebound congestion and rhinitis medicamentosa 6
• Do not use newer-generation antihistamines like terfenadine or loratadine plus pseudoephedrine for postviral cough – these have been shown ineffective for non-histamine-mediated cough 1
• Recognize that cough persisting beyond 3 weeks requires full diagnostic workup rather than continued empiric treatment 7
• Consider that allergic rhinitis itself may cause sedation and impairment, so using sedating antihistamines compounds this problem 3

Special Considerations

• For nocturnal cough disrupting sleep, first-generation sedating antihistamines may be appropriate due to their sedative properties 7, 8
• Allergen avoidance is always desirable but usually not completely possible 1
• Most patients show improvement within days to 2 weeks of initiating appropriate therapy 1
• Second-generation antihistamines are preferred for all patients, particularly those at higher risk for adverse effects from sedation (drivers, machinery operators, students) 3