A dry cough after a cold may be caused by post-infectious cough, cough variant asthma, chronic pharyngitis and other reasons. 1. Post-infectious cough: When the acute phase of respiratory infection disappears, the cough is still prolonged, commonly seen after the common cold. This symptom may be related to the incomplete healing of respiratory inflammation caused by colds and increased airway sensitivity. If symptoms are severe, cough suppressants such as dextromethorphan may be used. 2. Cough variant asthma: Colds may induce a cough variant asthma attack with paroxysmal coughing, mainly dry cough. Inhaled glucocorticosteroids, such as budesonide powder inhaler, are commonly used. 3. Chronic pharyngitis: some patients have chronic pharyngitis, when the throat is irritated, there will be itching, dry cough and other symptoms, you can use compound borax solution, compound chlorhexidine gargle gargle or take throat tablets to relieve symptoms. There are other diseases may also appear dry cough symptoms, if the symptoms do not relieve or aggravate, it is recommended to go to the hospital in time through the examination to clarify the diagnosis of the disease, targeted treatment.