What is the best treatment approach for a patient presenting with a dry cough, considering potential underlying conditions such as asthma or chronic obstructive pulmonary disease (COPD)?

Treatment of Dry Cough

For a patient with dry cough, start immediately with a first-generation antihistamine-decongestant combination to treat upper airway cough syndrome (UACS), then sequentially add inhaled corticosteroids with beta-agonists for asthma if no response in 1-2 weeks, followed by high-dose proton pump inhibitor therapy for GERD if cough persists after 2-4 weeks. 1, 2

Immediate Actions Before Starting Treatment

Stop ACE inhibitors immediately if the patient is taking one, as this alone may resolve the cough within days to 2 weeks (median 26 days). 1, 2

Counsel current smokers on cessation as a priority, as 90% of patients with chronic bronchitis will have cough resolution after quitting. 1, 2

Obtain a chest radiograph to rule out serious pathology such as pneumonia, pulmonary embolism, or lung cancer. 2

Step 1: Treat Upper Airway Cough Syndrome (UACS) First

Begin with a first-generation antihistamine (like chlorpheniramine) combined with a decongestant as initial empiric therapy. 1, 2, 3

• First-generation antihistamines are specifically required; newer non-sedating antihistamines are ineffective for UACS-related cough. 2
• Expected response time is days to 1-2 weeks. 1
• Consider adding an intranasal corticosteroid spray to enhance upper airway control. 1
• The sedation from first-generation antihistamines is valuable, particularly if cough disturbs sleep. 3

Step 2: Add Asthma Treatment if Inadequate Response After 1-2 Weeks

If cough persists after 1-2 weeks of UACS treatment, initiate inhaled corticosteroids (ICS) combined with long-acting β-agonists (LABA). 1, 2

• Continue the UACS treatment while adding asthma therapy, as multiple causes frequently coexist. 1
• Expected response time is 2-8 weeks. 1, 2
• Do not use albuterol alone for chronic cough not due to asthma, as it is ineffective. 1
• Medical history alone is unreliable for diagnosing asthma as a cause of cough; bronchoprovocation challenge testing is ideal if available. 2

Special Consideration for Known Asthma/COPD Patients

For patients with pre-existing asthma or COPD, optimize existing controller medications first before adding new therapies. 1

Spirometry is essential to distinguish asthma from COPD: asthma shows reversible airway obstruction (>12% and >200 mL improvement in FEV1 with bronchodilators), while COPD shows persistent obstruction (FEV1/FVC <70%) that is not reversible. 4

Step 3: Add GERD Treatment if Still No Response After 2-4 Weeks

If cough persists despite treatment for UACS and asthma, initiate high-dose proton pump inhibitor (PPI) therapy with dietary modifications. 1, 2

• Continue previous treatments (UACS and asthma therapies) while adding GERD treatment. 1
• Expected response time is 2 weeks to several months. 1, 2
• GERD can cause cough even without typical gastrointestinal symptoms like heartburn. 1
• Consider adding a prokinetic agent like metoclopramide if initial GERD therapy fails. 5

Symptomatic Antitussive Options (Adjunctive, Not Primary Treatment)

While pursuing the diagnostic algorithm above, symptomatic relief can be considered:

Dextromethorphan or codeine can provide short-term symptomatic relief for dry, bothersome cough, especially at night. 5, 6, 3

• These central cough suppressants have limited efficacy for upper respiratory infection-related cough and should not be used as primary treatment. 1
• Honey may be considered for patients over 1 year of age as a cough suppressant. 6
• Avoid expectorants, mucolytics, and bronchodilators for uncomplicated dry cough, as there is no consistent evidence of benefit. 6

Step 4: Consider Non-Asthmatic Eosinophilic Bronchitis (NAEB)

If cough persists despite adequate trials of UACS, asthma, and GERD treatments:

Perform induced sputum testing for eosinophils, or administer an empiric trial of oral corticosteroids if testing is unavailable. 2

When to Refer to a Cough Specialist

Refer patients to a specialist cough clinic if cough persists beyond 8 weeks despite sequential treatment of UACS, asthma, and GERD. 1, 2

Specialist evaluation may include high-resolution CT chest and bronchoscopy to evaluate for bronchiectasis, occult interstitial disease, endobronchial tumor, sarcoidosis, or eosinophilic/lymphocytic bronchitis. 5, 2

For refractory idiopathic chronic cough, specialists may consider low-dose morphine, gabapentin, or baclofen under close supervision. 2

Critical Pitfalls to Avoid

Do not prescribe antibiotics for dry cough unless clear evidence of bacterial infection exists, as most short-term coughs are viral. 5, 1

Do not suppress productive cough in conditions like pneumonia or bronchiectasis, as clearance is important. 1

Do not use colored sputum as an indicator for antibiotics, as it does not reliably differentiate bacterial from viral infections. 6

Red Flags Requiring Immediate Medical Attention

Patients should see a doctor if they experience: hemoptysis, breathlessness, prolonged fever with feeling unwell, or symptoms persisting beyond 3 weeks. 5, 6

Patients with pre-existing conditions (chronic bronchitis/COPD, heart disease, diabetes, asthma) or recent hospitalization require closer monitoring. 5