How should I manage a 35-year-old man with a dry cough, normal chest X-ray, brief response to oral steroids, no history of asthma, FeNO 17 ppb, and who has been trialed on inhalers?

Management of Chronic Dry Cough with Low FeNO and Brief Steroid Response

This patient most likely has cough-variant asthma despite the low FeNO of 17 ppb, and should be treated with a diagnostic/therapeutic trial of prednisone 30 mg daily for 1-2 weeks followed by transition to inhaled corticosteroids for 8 weeks, while simultaneously treating for upper airway cough syndrome with a first-generation antihistamine/decongestant combination. 1

Diagnostic Reasoning

The clinical picture strongly suggests cough-variant asthma based on several key features:

• The brief response to oral steroids is highly suggestive of cough-variant asthma, as this response pattern is the diagnostic hallmark of this condition 1, 2
• A FeNO of 17 ppb does not exclude cough-variant asthma—the American College of Chest Physicians recommends testing for bronchial hyperresponsiveness and eosinophilic inflammation, but a therapeutic corticosteroid trial is an acceptable alternative diagnostic approach when these tests are unavailable or inconclusive 1
• The normal chest X-ray and lack of asthma history are typical for cough-variant asthma, which presents with isolated cough without wheezing or dyspnea 2, 3
• The peak flow of 5.8 (assuming L/sec or similar metric) requires spirometry to assess for airflow limitation, but cough-variant asthma can exist with normal spirometry 1, 3

Recommended Treatment Algorithm

Step 1: Confirm Diagnosis with Therapeutic Trial (Weeks 1-2)

• Prescribe prednisone 30 mg daily for 1-2 weeks as both a diagnostic and therapeutic intervention 1, 2
• Complete resolution of cough within this timeframe confirms cough-variant asthma 2
• If cough resolves, immediately transition to inhaled corticosteroids rather than continuing oral steroids 1, 2

Step 2: Transition to Inhaled Corticosteroids (Weeks 2-10)

• Start fluticasone propionate 200 mcg twice daily (or equivalent high-dose inhaled corticosteroid) after the oral steroid trial 1, 4
• Complete resolution may require up to 8 weeks of inhaled corticosteroid therapy 1
• Inhaled corticosteroids are the choice drugs for long-term management as they relieve cough and decrease bronchial hyperresponsiveness, reducing the risk of progression to classic asthma 4

Step 3: Simultaneously Treat Upper Airway Cough Syndrome

• Start a first-generation antihistamine/decongestant combination immediately (e.g., chlorpheniramine with sustained-release pseudoephedrine) 1, 5, 6
• Upper airway cough syndrome accounts for up to 90% of chronic cough cases in combination with asthma and GERD, and multiple causes frequently coexist 5, 6
• Continue this therapy for at least 2 weeks alongside the asthma treatment 5

Step 4: Add PPI Therapy if No Response (Week 2-10)

• If cough persists despite adequate treatment of both cough-variant asthma and upper airway cough syndrome after 2 weeks, initiate omeprazole 20-40 mg twice daily before meals for at least 8 weeks plus dietary modifications 1, 5
• GERD frequently coexists with other causes of chronic cough and may take up to 3 months to show improvement 5

Critical Pitfalls to Avoid

• Do not rely on FeNO alone to exclude cough-variant asthma—the brief response to oral steroids is more diagnostically significant than the low FeNO value 1, 7
• Do not use second-generation antihistamines (cetirizine, loratadine, fexofenadine) as they are ineffective for upper airway cough syndrome due to lack of anticholinergic activity 5
• Do not discontinue partially effective treatments prematurely—maintain all therapies that provide some benefit, as multiple causes frequently coexist 5
• Do not continue oral steroids long-term—transition to inhaled corticosteroids after the diagnostic trial to avoid systemic side effects including immunosuppression, hyperglycemia, and osteoporosis 1
• Avoid inhaled steroid-induced cough by using proper inhaler technique with a spacer device; if cough worsens with inhaled steroids, consider switching from beclomethasone to triamcinolone or fluticasone due to different dispersant components 1

Monitoring and Follow-Up

• Reassess at 2 weeks after initiating the prednisone trial to confirm diagnosis and transition to inhaled therapy 1, 2
• Reassess at 8-10 weeks to evaluate complete response to inhaled corticosteroids 1
• If no improvement after systematic treatment of all three common causes (upper airway cough syndrome, asthma, GERD), consider bronchoscopy or referral to pulmonology for less common etiologies 5, 6
• Monitor blood pressure if using decongestants, as they can worsen hypertension 5