Why does a cough linger for weeks after you feel better?
Because the infection clearing and the airways recovering are separate processes, and the second takes considerably longer.
What a cough is. A protective reflex clearing the airways, triggered by receptors in the throat, trachea and bronchi responding to irritation, mucus or foreign material.
Why it persists after recovery:
Airway inflammation takes weeks to settle. The infection damaged and inflamed the lining. Even once the virus is gone, inflamed tissue remains and the healing surface is raw.
Cough receptor hypersensitivity. This is the main mechanism. Inflammation lowers the threshold at which cough receptors fire, so triggers that would normally do nothing — cold air, talking, laughing, exercise, a change in temperature, lying down — provoke coughing. The reflex is genuinely over-sensitive rather than responding to anything real.
Damaged cilia. The tiny hairs clearing mucus upward are destroyed by many respiratory infections and take weeks to regenerate. Until they do, mucus is cleared by coughing instead.
Continued mucus production, including post-nasal drip from sinuses that remain inflamed.
A self-perpetuating cycle, where coughing irritates the airway and provokes more coughing.
How long is normal. Post-infectious cough commonly lasts three to eight weeks, and this is well documented. A cough lasting a fortnight after a cold is entirely ordinary, and antibiotics do nothing for it.
What helps: honey has reasonable evidence, particularly in children over one; steam and humidity; avoiding known triggers; and simple demulcents. Over-the-counter cough medicines have weak evidence overall.
When to seek medical advice — and these matter:
Cough lasting more than three weeks warrants review under UK guidance, and more than eight weeks definitely.
Coughing blood, breathlessness, chest pain, unexplained weight loss, fever that returns, or night sweats.
A cough that changes character, or in a smoker.
Wheeze, which may indicate asthma unmasked by the infection.