What is the management for allergic cough?

Management of Allergic Cough

For allergic cough, start with a first-generation antihistamine/decongestant combination (such as dexbrompheniramine plus sustained-release pseudoephedrine) as first-line therapy, and add intranasal corticosteroids if no improvement occurs within 1-2 weeks. 1, 2, 3

Initial Treatment Approach

First-Line Therapy

• Begin with a first-generation antihistamine/decongestant combination as the most effective initial treatment for allergic cough related to upper airway cough syndrome (UACS). 1, 2, 3
• Specific effective combinations include dexbrompheniramine maleate plus sustained-release pseudoephedrine sulfate, or azatadine maleate plus sustained-release pseudoephedrine sulfate. 3
• First-generation antihistamines are superior to newer non-sedating antihistamines due to their anticholinergic properties, which are critical for treating the cough component. 2, 3
• Newer-generation antihistamines (like loratadine) are ineffective for non-allergic causes of cough, though they may provide some benefit specifically for allergic rhinitis-related symptoms. 3, 4

Adding Intranasal Corticosteroids

• If no improvement after 1-2 weeks with the antihistamine-decongestant combination, add intranasal corticosteroids such as fluticasone 100-200 mcg daily or mometasone furoate. 2, 3, 5
• For allergic rhinitis-related cough specifically, intranasal corticosteroids can be started immediately alongside antihistamines rather than waiting. 2
• Continue intranasal corticosteroids for 3 months after cough resolution to prevent recurrence. 2
• A single RCT demonstrated that mometasone furoate nasal spray significantly improved daytime cough severity in patients with seasonal allergic rhinitis (P = 0.049). 5

Treatment Algorithm Based on Severity

Moderate-to-Severe Allergic Rhinitis with Cough

• For moderate-to-severe cases, use combination intranasal fluticasone propionate plus intranasal azelastine, which provides 40% superior symptom reduction compared to either agent alone. 2
• This combination is particularly effective when initial monotherapy fails. 2

Refractory Cases

• Add ipratropium bromide nasal spray (42 mcg per spray, 2 sprays per nostril 4 times daily) if patients don't respond to antihistamine/decongestant combinations, as it provides anticholinergic drying effects without systemic cardiovascular side effects. 2, 3
• Consider oral leukotriene inhibitors (montelukast 10 mg daily) as an alternative, though they are less effective than intranasal corticosteroids. 2

Identifying and Treating Underlying Causes

Non-Asthmatic Eosinophilic Bronchitis (NAEB)

• If cough persists despite adequate upper airway treatment, consider NAEB, particularly in patients with normal chest radiograph, normal spirometry, and no evidence of variable airflow obstruction. 1
• Confirm diagnosis with induced sputum testing for eosinophils or bronchial wash fluid obtained by bronchoscopy. 1
• First-line treatment for NAEB is inhaled corticosteroids (ICSs), except when a causal allergen is identified. 1
• When a causal allergen or occupational sensitizer is identified, avoidance is the best treatment. 1
• If symptoms persist despite high-dose ICSs, add oral corticosteroids. 1

Asthma-Related Cough

• If bronchoprovocation challenge is positive or asthma is suspected, treat with ICSs and β-agonists, with complete resolution potentially requiring up to 8 weeks. 1
• Consider a 5-10 day course of oral corticosteroids (prednisone 40 mg/d) for patients with positive methacholine challenge whose cough remains troublesome and who haven't responded to inhaled medications. 1, 6
• Add leukotriene inhibitors before oral corticosteroids if inhaled medications are ineffective. 1

Critical Pitfalls and Caveats

Medication Selection Errors

• Never use newer-generation antihistamines as monotherapy for allergic cough—they lack the anticholinergic properties necessary for cough suppression. 2, 3
• Never use topical nasal decongestants (oxymetazoline, xylometazoline) for more than 3-5 consecutive days due to risk of rhinitis medicamentosa (rebound congestion). 3
• Do not discontinue intranasal corticosteroids prematurely—the 3-month continuation after cough resolution is critical for preventing recurrence. 2

Monitoring and Safety

• Monitor blood pressure after initiating decongestant therapy, as decongestants can worsen hypertension, cause tachycardia, insomnia, irritability, and palpitations. 3
• To minimize sedation from first-generation antihistamines, start with once-daily dosing at bedtime for a few days before increasing to twice-daily therapy. 3
• Monitor for urinary retention, jitteriness, and increased intraocular pressure in glaucoma patients. 3

Diagnostic Considerations

• Approximately 20% of patients have "silent" upper airway cough syndrome with no obvious postnasal drip symptoms yet still respond to treatment—don't exclude UACS based on absence of typical symptoms. 3
• If cough persists despite adequate upper airway treatment for 2 weeks, proceed with sequential evaluation for asthma/NAEB and gastroesophageal reflux disease (GERD). 1, 3
• Maintain all partially effective treatments rather than discontinuing them prematurely, as multiple causes often coexist. 3

Adjunctive Therapy

Nasal Saline Irrigation

• Add nasal saline irrigation to improve symptoms through mechanical removal of mucus and enhanced ciliary activity—irrigation is more effective than saline spray. 3
• Longer treatment duration (mean 7.5 months) shows better results than shorter courses. 3

Allergen Avoidance

• When a specific allergen is identified, avoidance is the most effective long-term strategy. 1
• Consider allergy testing and evaluation of home/workplace environments if there is potential environmental exposure. 1