Always coughing but no sputum, dry cough can be caused by many factors, infectious and non-infectious factors, which can lead to a patient’s long-term enduring dry cough, but with little secretion. The clinical causes of dry cough without sputum are as follows: 1. stimulation by various physical and chemical factors: for example, in patients who have been smoking for a long time, the stimulation by smoke can lead to a long-term dry cough without sputum; 2. allergy: whether it is food allergy, pollen or paint allergy, it can lead to a dry cough. No sputum is due to the stimulation of physical and chemical factors, and allergy does not lead to an increase in respiratory secretions, and if it leads to an increase in secretions, it is impossible to have no sputum. 3, various infections: such as Mycobacterium tuberculosis infection, chlamydia, mycoplasma infection, viral infection, fungal infection, may lead to respiratory tract, and the possibility of an increase in mucus secretion is relatively low, so the patient will also have a dry cough without sputum. 4, bronchial lung cancer: it can also lead to patients to cough for a long time without sputum, or dry cough without sputum. 5. Other diseases: such as gastroesophageal reflux, which can appear as a cough without stopping. If old cough and no obvious coughing sputum occur, you should go to the hospital for further examination to clarify the cause.