Cough belongs to the body’s reflex defense action, determine whether the cough is allergy or inflammation can be combined with medical history, clinical symptoms and related examination results. 1. Allergy: The patient will have a history of allergy, mostly triggered by exposure to pollen, cold air, animal dander, dust, etc., and at the same time there will be symptoms such as itching of the throat or nasal passages, and foreign body sensation. Their allergen skin test results are positive and there is no sign of airway hyperreactivity. The eosinophils in sputum examination are normal, but the peripheral blood eosinophils in routine blood examination are increased. 2. Inflammation: patients will have clinical symptoms such as runny nose, fever, muscle pain, nasal congestion and so on. A significant increase in the number of leukocytes can be found through routine blood tests. However, there may also be normal or decreased white blood cells. Secondly, sputum examination results show elevated eosinophils. In addition to allergies and inflammation, the cough may be caused by other reasons. It is recommended that patients with coughs visit the hospital in time to improve the examination in order to clarify the cause of the cough.