The eight week mark

A cough that follows a cold is expected to linger for three to eight weeks. Beyond that window the question changes from how long to why, and the answer is usually one of four things. Reflux, post nasal drip, asthma, or a medication effect.

Features that change the plan

Bringing up blood, breathlessness at rest, night sweats, weight loss, or a cough that started suddenly in a smoker are not watchful waiting symptoms. Each one shortens the path to imaging.

What spirometry adds

A short breathing test measures how much air moves and how quickly. It takes minutes, and it separates obstruction from restriction far more reliably than listening with a stethoscope alone.