Some coughs are harmless, while others merit medical attention. A cough is a very common, and irritating, symptom. Most often it's part and parcel of a cold or flu and, aside from resting and trying not to spread the infection, there's little you can do. Other coughs, however, may signify a more serious underlying medical condition.
Doctors at the Mayo Clinic point out the situations where a cough needs prompt medical attention. First, if you have a history of lung disease, including cancer, or are a current or past smoker, be wary if you develop a cough. If your cough lasts for four to six weeks, you might have asthma or another lung problem.
And if your cough is accompanied by shortness of breath, or fever, you need urgent medical help. The same applies if you start to bring up blood-coloured sputum. Yellow-coloured sputum may indicate a serious bacterial infection - another indicator for a doctor's care.