The causes of runny nose and sneezing include: 1, acute upper respiratory tract infection: i.e. cold, including influenza and common cold. When you have a cold, the mucosal secretions of the nasal cavity increase, and sneezing is to discharge nasal secretions; 2. Allergic rhinitis: including variant rhinitis and hay fever; 3. Vasoconstrictive rhinitis: mainly runny nose, also sneezing, reacting to the temperature and humidity of the environment and allergic substances, and sneezing; 4. Non-allergic rhinitis: the allergen test is negative, but the nasal mucosa secretes histamine-like substances, leading to sneezing.