What causes a cough that worsens when lying down?

Cough When Lying Down: Causes and Clinical Approach

Gastroesophageal reflux disease (GERD) is the primary cause to consider when cough worsens with lying down, though reflux is known to be related to posture (bending or lying down), and while there is no direct evidence demonstrating a connection between posture and reflux-related cough, the clinical pattern strongly suggests this relationship. 1

Primary Causes of Position-Dependent Cough

Gastroesophageal Reflux Disease (GERD)

• GERD should be your first consideration when patients report cough that worsens when lying down, as reflux is directly related to posture changes 1
• In retrospective reviews of patients with proven reflux cough, 75% had cough associated with food or postprandial symptoms, and 90% had cough with phonation (talking, laughing, singing) 1
• Critical pitfall: Up to 75% of GERD-related cough occurs without typical gastrointestinal symptoms (silent GERD), so absence of heartburn does NOT rule out reflux as the cause 2
• The mechanism involves refluxed stomach contents irritating the throat and airways during recumbency, with symptoms manifesting during or after lying down 2
• Maximum stimulation for transient opening of the lower esophageal sphincter occurs approximately 10 minutes postprandially 1

Congestive Heart Failure

• Pulmonary edema, whether cardiogenic or noncardiogenic, can cause cough and occasionally presents with cough as the sole manifestation 1
• Positional cough (orthopnea-related) should prompt evaluation for heart failure, particularly in patients with risk factors 1

Postnasal Drip/Upper Airway Cough Syndrome

• During sleep, mucus accumulates in the back of the throat and upper airways, leading to coughing upon lying down or waking 2
• This accounts for a significant portion of chronic cough cases (part of the >90% attributed to upper airway cough syndrome, GERD, and asthma) 2, 3

Secondary Considerations

Asthma

• Asthma can cause coughing that worsens at night or when lying down due to circadian variations in airway responsiveness 2
• Look for triggers such as exercise or cold air exposure that worsen symptoms 2
• Cough-variant asthma may present without wheezing 3, 4

Medication-Related

• ACE inhibitors alter cough reflex sensitivity and can aggravate cough from any cause, with incidence as high as 16% 1, 2
• The cough is not dose-related and can occur hours to over a year after starting treatment 1
• Median time to resolution after stopping ACE inhibitors is 26 days, but can take up to 40 weeks 1

Diagnostic Approach

Initial Evaluation

• Obtain a detailed history focusing on:
  • Timing relative to meals (postprandial symptoms suggest GERD) 1
  • Cough with phonation (talking, laughing, singing suggests GERD due to lack of diaphragmatic closure of lower esophageal sphincter) 1
  • Presence or absence of heartburn (remember: absence doesn't rule out GERD) 2
  • Medication review, particularly ACE inhibitors 1, 2
  • Cardiac risk factors and symptoms of heart failure 1

Clinical Testing

• Chest radiography is essential to rule out infectious, inflammatory, and malignant thoracic conditions 3
• Spirometry if asthma is suspected 3
• Consider cardiac evaluation if heart failure is suspected 1

Empiric Treatment Strategy

• For GERD-suspected cases: Trial of proton pump inhibitors and lifestyle modifications (elevate head of bed, avoid late meals) 2, 3
• For asthma-suspected cases: Trial of inhaled corticosteroids 3
• If on ACE inhibitor: Switch to angiotensin II receptor blocker, as most patients with ACE inhibitor-associated cough can tolerate these 1

Important Clinical Pearls

• Sleep suppresses the cough reflex, particularly during deep sleep stages 3 and 4, so true nocturnal cough (during sleep) is less common than cough when lying down or upon waking 1, 2
• A cough that abates overnight may actually be due to reflux, as the lower esophageal sphincter closes during sleep 2
• Women, particularly middle-aged women, have higher prevalence of chronic cough and more sensitive cough reflex 2
• If common causes have been evaluated and treated without success, consider uncommon causes including pulmonary embolism (cough develops in nearly half of patients with documented PE) 1