<s>[INST] hi .im female 22 years ...im having cough from last two months ...consulted several ent specialist ....but still my cough is there...with irritation in trachea and sometimes yello sputum....it continues for the whole day ....i need to know about its cause [/INST] HI, thanks for using Chat Doctor The most common causes of persistent cough are: (1) post nasal Chat Doctor. The fact that you are noting sputum means that this is the most likely cause for you. This can be treated with oral anti histamines and topical steroid nasal sprays. In most cases it is caused by an allergen. If this can be identified and exposure reduced then symptoms should also reduce.(2)HERD- gastroesophageal reflux is also a common cause. Some persons may not be aware of the reflux and present with the cough only.(3)asthma hope this helps </s>