Causes
Three conditions account for most chronic cough in nonsmokers with a normal chest X-ray, and many patients have more than one:- Upper airway cough syndrome (postnasal drip): Mucus dripping down the back of the throat from allergies or chronic postnasal drip triggers throat clearing and cough.
- Asthma: Cough-variant asthma may cause coughing as the only symptom, often worse at night, with exercise, or in cold air.
- Acid reflux: GERD and its throat-focused form, laryngopharyngeal reflux, can irritate the airway even without heartburn.
- Other causes: Smoking, ACE-inhibitor blood pressure medications (such as lisinopril), chronic bronchitis, infections that leave a lingering cough, and, less commonly, lung disease or tumors.
Diagnosis
Evaluation begins with a careful history — smoking, medications, heartburn, allergies, and the cough's timing — and a physical exam. A chest X-ray is usually obtained to exclude structural lung disease. Because the common causes do not always announce themselves, doctors often treat the most likely culprit first and use the response as a diagnostic clue. Breathing tests (spirometry) check for asthma, and further testing such as CT imaging or specialist referral is reserved for cough that resists initial therapy or comes with warning signs.Treatment
Treatment targets the underlying cause, and improvement may take several weeks:- For postnasal drip: Nasal steroid sprays such as fluticasone, antihistamines, and saline rinses calm the upper airway.
- For asthma: Inhaled corticosteroids and bronchodilators; montelukast is sometimes added for allergic or cough-variant asthma.
- For reflux: Acid-suppressing medication such as omeprazole, along with weight loss, avoiding late meals, and elevating the head of the bed.
- Medication review: If an ACE inhibitor is the trigger, switching to a different blood pressure medication typically resolves the cough within a few weeks.
- Smoking cessation: Essential — a smoker's cough that changes character warrants evaluation, not reassurance.