How to evaluate and treat nocturnal cough?

Evaluation and Treatment of Nocturnal Cough

Nocturnal cough should be evaluated using the same systematic approach as chronic cough, as the timing of cough (including nighttime occurrence) does not predict its underlying cause and should not be used diagnostically. 1, 2

Key Principle: Timing Is Not Diagnostic

• The presence or absence of nocturnal cough has no predictive value for determining the etiology of chronic cough 1, 2
• Cough from multiple conditions—including chronic bronchitis, gastroesophageal reflux disease (GERD), upper airway cough syndrome (UACS), and asthma—can all present with or without nighttime symptoms 1, 3
• Cough caused by GERD and other conditions is unlikely to occur once patients fall asleep, so absence of nocturnal coughing does not exclude any diagnosis 1

Systematic Evaluation Approach

Initial Assessment

• Determine cough duration: acute (<3 weeks), subacute (3-8 weeks), or chronic (>8 weeks) 1, 3
• Obtain chest radiograph to rule out pneumonia, structural abnormalities, masses, interstitial disease, or heart failure 3, 4
• Review medication list and discontinue ACE inhibitors if present, as they commonly cause persistent dry cough 5, 3, 4
• Assess smoking status and counsel on cessation, as chronic bronchitis is a leading cause in smokers 3, 4

The "Big Three" Causes Account for 90% of Cases

For chronic cough (including nocturnal cough), systematically evaluate and treat the three most common causes sequentially: upper airway cough syndrome (UACS), asthma, and GERD 1, 3

Treatment Algorithm

1. Upper Airway Cough Syndrome (UACS)

• Look for nasal discharge, throat clearing, or postnasal drip sensation 3
• Initiate first-generation antihistamine/decongestant combination as first-line therapy 5, 3, 4
• First-generation sedating antihistamines are particularly suitable for nocturnal cough due to their sedative properties 1
• Allow adequate treatment duration before declaring failure 3

2. Asthma or Nonasthmatic Eosinophilic Bronchitis

• Assess for triggers such as cold air, exercise, or nighttime worsening 3
• Perform spirometry with bronchodilator response or bronchoprovocation challenge 5, 3
• If testing unavailable, initiate empiric trial of inhaled corticosteroids combined with bronchodilators 5, 3, 4
• For nonasthmatic eosinophilic bronchitis, inhaled corticosteroids alone are first-line treatment 5, 4

3. Gastroesophageal Reflux Disease (GERD)

• Assess for heartburn, regurgitation, or sour taste (though these may be absent) 3
• Initiate high-dose proton pump inhibitor (PPI) therapy along with dietary modifications and lifestyle changes 3, 4
• Add prokinetic therapy if little or no response to PPI alone 4
• Treatment duration should be 4-8 weeks before reassessing 1

Symptomatic Relief for Nocturnal Cough

While addressing underlying causes:

• Dextromethorphan 60 mg provides maximum cough reflex suppression with prolonged effect 1
• Menthol by inhalation provides acute but short-lived cough suppression 1
• First-generation sedating antihistamines are particularly appropriate for nocturnal cough 1
• Simple home remedies like honey and lemon may provide symptomatic benefit 1

Critical Pitfalls to Avoid

• Do not assume nocturnal cough indicates psychogenic cough or habit cough—this is diagnostically unreliable 1
• Do not rely on cough character (wet, dry, barking) for diagnosis, as it has no predictive value 1, 3, 4, 2
• Multiple simultaneous causes are present in 59% of chronic cough cases—sequential and additive therapy is often necessary 1, 3, 2
• Avoid stopping treatment prematurely before the expected response time for each condition 3
• Do not use codeine or pholcodine as they have greater adverse effects than dextromethorphan without superior efficacy 1

When Initial Approach Fails

If cough persists despite sequential trials:

• Obtain high-resolution CT scan to evaluate for bronchiectasis, interstitial lung disease, or occult masses 3
• Consider 24-hour esophageal pH monitoring if GERD suspected but empiric therapy failed 3
• Perform bronchoscopy to evaluate for endobronchial lesions, sarcoidosis, or eosinophilic bronchitis 3
• For refractory unexplained chronic cough, consider gabapentin starting at 300 mg once daily, escalating to maximum 1,800 mg daily in divided doses 3
• Multimodality speech pathology therapy is a reasonable alternative for refractory cases 3