Chest CT is normal, but frequent coughing may be pharyngitis, allergic cough, gastroesophageal reflux, cough variant asthma, postnasal drip syndrome, etc. 1. Pharyngitis, due to inflammation of the throat, stimulation of the local mucosa, resulting in coughing, at this time the lung CT examination can not clarify the cause of the disease, need to carry out laryngoscopy and other tests. 2. Allergic cough, due to contact with allergic substances without self-awareness, can cause allergic cough, it is recommended to avoid contact with allergens, symptomatic anti-allergy such as loratadine, combined with cotrimoxazole treatment. 3. Gastroesophageal reflux (GERD). Refluxed gastric juices can irritate the esophagus and cause coughing, which requires acid-suppressing treatment. 4. Cough variant asthma is also one of the common causes, there is no clear manifestation in lung CT, complete lung function test, airway provocation test can confirm the diagnosis. 5. Postnasal drip syndrome, due to nasal secretions stimulate the throat, can lead to frequent cough performance. It needs to be treated for rhinitis. 6. Eosinophilic bronchitis, often associated with inhalation of allergens, harmful substances, etc., manifested as a dry cough, checking the induced sputum eosinophil Oh ratio of > 3%. Good response to glucocorticoid therapy. 7. drug side effects, such as angiotensin-converting enzyme inhibitor drugs, captopril, enalapril, etc., commonly used in patients with hypertension, some patients with dry cough side effects, it is recommended to find timely adjustment. There are many reasons other than lung disease that can cause coughing, the specific cause needs to be clarified after medical examination, and at the same time, according to the doctor’s instructions for treatment.