Persistent Cough

More than two weeks. In India a cough lasting beyond two weeks should always prompt consideration of tuberculosis, and testing for it is free in the government programme.

It can. A dry, tickly cough is a known effect of ACE inhibitors, a common class of blood pressure medicine. Do not stop the tablet yourself — tell your doctor, who can usually switch you to an alternative.

It always needs to be seen by a doctor promptly, whatever the amount. It can come from tuberculosis, a chest infection or other lung conditions, and the cause needs identifying rather than waiting to see whether it settles.

A cough after a cold or viral illness commonly lingers for two to three weeks after the other symptoms have gone, because the airways stay irritated for a while. That is normal and does not mean the infection is still there. Beyond two weeks it should be assessed rather than waited out.

The usual reasons a cough drags on are a post-infectious cough after a viral illness, asthma, acid reflux, COPD in smokers, air pollution or dust exposure, and blood pressure medicines of the ACE inhibitor class. In India, tuberculosis must also be considered for any cough beyond two weeks. Which one applies needs a doctor and usually a chest X-ray or sputum test — it is not something to work out at home.

See a doctor and say clearly how long it has been. A cough of a month or more needs investigation, not another course of syrup. Ask specifically about testing for tuberculosis, which is free in the government programme, particularly if you also have evening fever, night sweats or weight loss.

Usually yes. A cough that comes with a cold or a viral illness is doing a job — clearing the airways — and a few days of it is ordinary. See a doctor sooner than two weeks if you are breathless, have chest pain, are coughing up blood, have a high fever that is not settling, or if the person coughing is a baby, is elderly, or has a lung or heart condition.

A dry cough brings nothing up and often feels tickly or scratchy. A wet or chesty cough brings up phlegm, which may be clear, white, yellow or green. The colour on its own does not decide whether you need an antibiotic — that is a common belief and it is wrong. Both types can follow a viral illness, and both need checking if they last beyond two weeks.

It is the cough left behind after an infection has gone. The airways stay irritated and twitchy for a while, so you keep coughing even though you are otherwise better. It commonly lasts two to three weeks after a cold and settles on its own. If it drags past that, or you also have fever, night sweats or weight loss, it should be looked at rather than waited out.

A cough that settles and then returns is worth mentioning to a doctor, because it points somewhere different from one that simply drags on. Common reasons are asthma, which often comes and goes and may be worse at night or with exercise or cold air; acid reflux; repeated infections, particularly in children; and allergies that follow a season. Keep a rough note of when it comes back and what you were doing — that pattern is genuinely useful to the doctor.