What is the cause and treatment of a nocturnal cough?

Causes and Treatment of Nocturnal Cough

Nocturnal cough is most commonly caused by gastroesophageal reflux disease (GERD), asthma, or upper airway cough syndrome, with treatment directed at the underlying cause rather than symptomatic management alone. 1

Common Causes of Nocturnal Cough

1. Gastroesophageal Reflux Disease (GERD)

• Characteristic pattern: Cough worsens after meals and in the morning 1
• Clinical profile suggesting GERD-related cough (91% accuracy):
  • Non-smoker
  • Not taking ACE inhibitors
  • Normal chest X-ray
  • Cough worsening after meals 1
• GERD is one of the three most common causes of chronic cough in non-smokers with normal chest X-rays 1

2. Asthma/Cough Variant Asthma

• May present with nocturnal cough without classic wheezing 2
• Only about one-third of children with isolated nocturnal cough (without wheezing, shortness of breath, or chest tightness) have asthma-like illness 2
• Cough that wakes patients from sleep may suggest asthma 2

3. Upper Airway Cough Syndrome (Post-nasal drip)

• Often associated with frequent throat clearing or sensation of post-nasal drip 2
• May be worse at night due to mucus accumulation in supine position 1

4. Obstructive Sleep Apnea (OSA)

• Recently recognized as a cause of chronic cough 3, 4
• Patients likely to be female and report GERD and rhinitis symptoms 5
• Often presents without daytime somnolence 3
• Consider when cough remains unexplained following investigations for common causes 3

5. Post-infectious Cough

• Can persist for weeks after respiratory infections 2
• Particularly common in children under 4 years 2

6. Medication-induced Cough

• ACE inhibitors can cause persistent cough 2, 1
• Resolves within days to 2 weeks (median 26 days) after discontinuation 1

Diagnostic Approach

1. Detailed history focusing on:

   • Timing of cough (worse after meals suggests GERD) 1
   • Associated symptoms (post-nasal drip, heartburn, wheezing) 1
   • Triggers (cold air, exercise, scents may indicate hypersensitive cough reflex) 2
   • Medication review (especially ACE inhibitors) 1
   • Smoking status 1

2. Initial testing:

   • Chest radiograph to rule out structural disease 1
   • Spirometry if asthma is suspected 1
   • Consider FeNO testing to identify steroid-responsive cough 1

3. For persistent unexplained cough:

   • Consider sleep study if snoring or other OSA symptoms present 3, 4
   • 24-hour esophageal pH monitoring for suspected GERD without response to empiric therapy 1

Treatment Algorithm

First-line treatments based on suspected cause:

1. For GERD-related nocturnal cough:

   • Intensive acid suppression with twice-daily proton pump inhibitor for at least 3 months 1
   • Consider adding alginate if needed 1
   • Lifestyle modifications (avoid late meals, elevate head of bed) 1

2. For asthma/bronchial hyperresponsiveness:

   • Inhaled corticosteroids and bronchodilators for 4 weeks 1
   • Short course of oral corticosteroids for severe symptoms 1

3. For upper airway cough syndrome:

   • First-generation antihistamine/decongestant combination for 2-4 weeks 1
   • First-generation antihistamines particularly helpful for nocturnal cough due to sedative properties 2

4. For OSA-related cough:

   • Continuous positive airway pressure (CPAP) therapy 5, 3
   • Optimize therapy for coexisting GERD if present 3

5. For post-infectious cough:

   • Short course of inhaled corticosteroids if cough affects quality of life 1
   • Consider inhaled ipratropium bromide as first-line therapy 1

Symptomatic treatment for nocturnal cough:

• Dextromethorphan for non-productive cough 1
• Menthol inhalation for short-term cough suppression 2
• First-generation antihistamines specifically for nocturnal cough 2, 1

Important Clinical Pearls

• Sleep normally suppresses cough, so persistent nocturnal cough suggests significant underlying pathology 5
• Cough frequency is typically much lower at night than during the day in healthy individuals 5
• The presence or absence of nocturnal cough is not helpful in establishing etiology but may be useful for monitoring treatment response 5
• Common pitfalls include failing to discontinue ACE inhibitors, not considering GERD as a cause, and inadequate duration of treatment (especially for GERD) 1
• For refractory cases, consider neuromodulators like gabapentin or speech pathology therapy for cough suppression techniques 1

Remember that nocturnal cough is often multifactorial, and treatment may need to address multiple underlying causes simultaneously for optimal symptom control.