What is the cause of a patient's worsening productive cough with clear to yellow sputum, improved for 8 days, then exacerbated at night, despite taking Robitussin (Guaifenesin) and using home remedies including garlic, with no fever and no history of smoking or ill contact?

Differential Diagnosis

• Single most likely diagnosis
  • Acute bronchitis: The patient's symptoms of a productive cough with clear to yellow sputum, worsening at night, and initial improvement followed by deterioration are consistent with acute bronchitis. The use of Robitussin, a cough suppressant, and home remedies like garlic also suggest a self-treated respiratory infection.
• Other Likely diagnoses
  • Postnasal drip: The patient's symptoms of a productive cough and worsening at night could be related to postnasal drip, especially if the patient has allergies or a sinus infection.
  • Asthma: Although the patient denies any ill contact, asthma could be a consideration, especially if the patient has a history of asthma or atopy.
  • Chronic obstructive pulmonary disease (COPD) exacerbation: Although the patient is a never smoker, COPD could still be a consideration, especially if the patient has other risk factors such as secondhand smoke exposure or occupational exposures.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Pneumonia: Although the patient denies fevers, pneumonia is a potentially life-threatening condition that should be considered, especially if the patient's symptoms worsen or if there are any signs of respiratory distress.
  • Pulmonary embolism: This is a rare but potentially life-threatening condition that should be considered, especially if the patient has any risk factors such as recent travel, immobility, or family history.
  • Tuberculosis: Although the patient denies any ill contact, tuberculosis is a potentially life-threatening condition that should be considered, especially if the patient has any risk factors such as recent travel to endemic areas or exposure to someone with TB.
• Rare diagnoses
  • Cystic fibrosis: This is a rare genetic disorder that could present with recurrent respiratory infections and productive cough.
  • Bronchiectasis: This is a rare condition characterized by permanent dilation of the bronchi, which could present with recurrent respiratory infections and productive cough.
  • Allergic bronchopulmonary aspergillosis: This is a rare condition characterized by an allergic reaction to Aspergillus fungus, which could present with recurrent respiratory infections and productive cough.