The common causes of dry throat and runny nose are acute upper respiratory tract infection, acute rhinitis, allergic rhinitis and so on. 1. Acute upper respiratory tract infection: the mucous membrane of the nose and the mucous membrane of the throat are infected by viruses, which cause congestion and edema of the mucous membrane, resulting in the appearance of runny nose and dry throat. 2. Acute rhinitis: the reaction of nasal mucosa caused by viral or bacterial infection, resulting in runny nose, nasal obstruction causing open-mouth breathing and dry throat. 3. Allergic rhinitis: after the nasal mucosa comes into contact with allergens, nasal congestion and runny nose occur, and open-mouth breathing due to nasal congestion causes dryness of the mucous membrane in the throat. Cause dry throat and runny nose, there may be other reasons, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, under the guidance of the doctor for standardized treatment.