What is a common cause of cough with variable productivity?

The correct answer is post-infectious cough syndrome, which is characterized by a cough that persists after the resolution of an upper respiratory tract infection. In this condition, individuals may experience a cough that varies in productivity; it can be either dry or associated with sputum production. The underlying mechanism involves irritation or inflammation in the airways that continues even after the infection has cleared.

Post-infectious cough syndrome typically occurs as a result of residual inflammation in the bronchial tubes or throat, which may lead to a chronic cough that can fluctuate from dry to productive. This is particularly common after viral infections, where cough can linger for weeks, reflecting the variability in the presence of sputum due to ongoing airway hypersensitivity.

Allergic rhinitis primarily causes symptoms like sneezing, nasal congestion, and runny nose rather than a cough that varies in productivity. Asthma can also lead to coughing, but it is usually associated with wheezing and is often more consistent in terms of productivity. Acute sinusitis may lead to a cough, primarily due to postnasal drip, but the cough is more likely to be consistently productive due to mucus drainage.

Therefore, post-infectious cough syndrome is the most fitting answer as it characterizes a cough that varies