Dry cough can be caused by allergies, bronchitis, bronchial foreign bodies, etc. Patients need to do allergen test, blood test, CT and other tests. 1. Allergy: If the patient comes into contact with allergens, such as pollen, dust, food, etc., or smells irritating odors, such as oil smoke, kerosene, incense smoke, etc.. All may induce dry cough. Patients can be tested by allergens lung function, nitric oxide breath test and immunoglobulin antibody test to determine whether there is an allergic dry cough. 2. Bronchitis: Infection will cause damage to the bronchial wall and mucosa, resulting in congestion and edema, which will further lead to an increase in the exudation of inflammatory secretions, which will irritate the bronchial wall and cause the patient to have a dry cough. It is necessary to improve the blood routine, chest X-ray or otorhinolaryngology local laryngoscopy, rhinoscopy and other examinations to clarify the focus of infection. 3. Bronchial foreign body: after inhalation of foreign body, it will constantly stimulate the local mucosa of bronchial tube, which may cause reflex choking cough, manifested as dry cough. Patients can confirm whether there is a foreign body through CT, bronchoscopy. Clinically, dry cough may also be caused by variant asthma, gastroesophageal reflux and so on. It is recommended that patients should go to a regular hospital in time to identify the cause of the disease, and take targeted treatment under the guidance of a professional doctor.