What is the recommended medical management for a patient presenting with allergic cough?

Medical Management of Allergic Cough

For patients with allergic cough, first-line treatment is inhaled corticosteroids (ICS), starting with a standard dose equivalent to beclomethasone 200-800 μg daily, combined with allergen avoidance when a specific trigger is identified. 1

Initial Diagnostic Considerations

Before initiating treatment, several key factors must be addressed:

• Exclude ACE inhibitor use immediately, as these medications are one of the most common causes of persistent dry cough and no patient with troublesome cough should continue taking them 2
• Obtain chest radiograph and spirometry to exclude other pathology and establish baseline airway function 1
• Consider smoking cessation counseling if applicable, as smoking is one of the commonest causes of persistent cough and appears dose-related 2

First-Line Treatment: Inhaled Corticosteroids

Initiate ICS immediately upon diagnosis with the following approach:

• Start with beclomethasone 200-800 μg daily equivalent (or fluticasone propionate 100-200 μg daily), administered twice daily with proper inhaler technique using large volume spacers for metered-dose inhalers 1
• Continue treatment for 4-8 weeks while monitoring cough symptoms, as maximum effect may take several days to weeks 1, 3
• Dry powder inhalers can be considered as first-line options due to ease of use and lower environmental impact 1

The evidence strongly supports ICS as first-line therapy because allergic cough often represents cough variant asthma or non-asthmatic eosinophilic bronchitis, both of which respond to corticosteroids even when spirometry is normal 1.

Stepwise Escalation for Inadequate Response

If cough persists after 4-8 weeks of standard-dose ICS:

• Increase ICS dose up to 2000 μg beclomethasone daily equivalent before adding additional agents 1
• Add a leukotriene receptor antagonist (montelukast) if response remains inadequate, as there is specific evidence supporting this combination in cough variant asthma 1
• Consider short-course oral corticosteroids (prednisolone 30 mg daily for 1-2 weeks) only after maximizing inhaled therapy and adding a leukotriene receptor antagonist 1

Adjunctive Treatment for Upper Airway Symptoms

When prominent nasal symptoms accompany the cough:

• Add topical nasal corticosteroids (such as fluticasone propionate nasal spray 100-200 μg daily) for patients with allergic rhinitis contributing to cough 2, 3
• First-generation oral antihistamines/decongestants can be used as initial empiric treatment for upper airway cough syndrome, though second-generation antihistamines (loratadine, cetirizine, fexofenadine) are preferred to avoid sedation and impairment 2, 4

Research evidence suggests that loratadine specifically may reduce cough frequency and intensity in patients with allergic rhinoconjunctivitis and cough 5, 6.

Diagnostic Confirmation and Monitoring

• Bronchial challenge testing (methacholine) should be performed to demonstrate airway hyperresponsiveness and distinguish cough variant asthma from non-asthmatic eosinophilic bronchitis 1
• A 2-week trial of oral prednisolone 30 mg daily serves both diagnostic and therapeutic purposes, as cough is unlikely to be due to eosinophilic airway inflammation if there is no response 2, 1
• Measure sputum eosinophil counts or fractional exhaled nitric oxide (FENO) in refractory cases to assess eosinophilic inflammation and predict corticosteroid responsiveness 1

Allergen Avoidance

• When a specific causal allergen or occupational sensitizer is identified, avoidance is the best treatment and should be implemented alongside pharmacotherapy 2
• Consider occupational causes in all patients with chronic cough due to eosinophilic airway disease 2

Critical Pitfalls to Avoid

• Do not use long-acting beta-agonists at step 3 in cough variant asthma, as there is no evidence supporting their use at this stage 1
• Do not use dexamethasone as a cough suppressant, as it provides no significant benefit for symptomatic relief of non-specific cough and may cause harm 7
• Ensure medication compliance and proper inhaler technique before escalating therapy, as apparent treatment failure is often due to poor adherence 1
• Do not diagnose idiopathic cough until gastroesophageal reflux disease has been excluded with intensive acid suppression (proton pump inhibitors for minimum 3 months), as reflux commonly coexists with or mimics allergic cough 2

Treatment Duration and Follow-up

• Reassess patients in 2-4 weeks after initiating treatment 7
• Once adequate control is achieved, attempt to decrease to maintenance dose (beclomethasone 100-200 μg daily equivalent) 1, 3
• Chronic anti-inflammatory therapy is appropriate given the presence of airway remodeling in cough variant asthma 1