Differential Diagnosis for a Cough that Only Happens at Night

• Single Most Likely Diagnosis
  • Asthma: This condition often worsens at night due to various factors such as cooler air, increased exposure to allergens like dust mites, and the natural circadian rhythm that can affect lung function. Nocturnal cough is a common symptom of asthma.
• Other Likely Diagnoses
  • Gastroesophageal Reflux Disease (GERD): Stomach acid reflux can trigger coughing, especially when lying down at night. This is because gravity no longer helps keep stomach contents down, and the esophageal sphincter may be more relaxed, allowing acid to rise into the throat.
  • Postnasal Drip: Also known as upper airway secretion syndrome, this condition involves the dripping of mucus from the back of the nose down into the throat, which can trigger coughing, especially at night when lying down.
  • Allergic Rhinitis: Similar to asthma, allergies can cause symptoms to worsen at night, leading to coughing due to postnasal drip or direct irritation of the airways.
• Do Not Miss Diagnoses
  • Heart Failure: Congestive heart failure can lead to pulmonary edema, which may cause a cough that worsens when lying down (orthopnea). This is a critical diagnosis not to miss due to its severe implications.
  • Pneumonia: Certain types of pneumonia can present with a cough that is worse at night. It's crucial to consider this diagnosis, especially in vulnerable populations like the elderly or those with compromised immune systems.
  • Lung Cancer: Although less common, lung cancer can cause a persistent cough, which might be more noticeable at night. Given the severity of this condition, it's essential to rule it out, especially in smokers or those with a significant smoking history.
• Rare Diagnoses
  • Cystic Fibrosis: This genetic disorder leads to the production of thick, sticky mucus that can clog the airways and cause persistent coughing, which might be worse at night.
  • Bronchiectasis: A condition characterized by damaged, widened airways, which can lead to a chronic cough. The cough might be more pronounced at night due to increased mucus production and the effects of gravity on mucus clearance.