Colds are infectious diseases of the upper respiratory tract caused mainly by viral infections. Patients often experience symptoms such as nasal discomfort, sneezing, runny nose, fever, cough and headache. There are two types of colds: common cold and influenza. A runny nose during a cold is caused by a virus that invades the body’s throat and binds with airway epithelial cells, causing the body’s immune response to produce a large number of protective factors. While these beneficial factors kill the virus and protect themselves, they also increase the permeability of the blood vessel wall in the nasopharynx, and some plasma leaks out into the nasal mucosa, which in turn increases the secretion of glands in the nasal cavity, resulting in more nasal discharge than usual, and symptoms such as runny nose and nasal inaeration. In addition, some patients may also experience cough, phlegm, headache, fever and other symptoms. Runny nose is a common symptom of cold. Drinking water regularly and cleaning in time can relieve nasal congestion and other discomforts. If you feel that the symptoms of cold are heavy or accompanied by high fever, it is recommended to visit the respiratory department in time to avoid aggravation of the condition. In daily life, patients should pay attention to avoid getting cold, avoid straining, strengthen physical exercise and improve their immunity to reduce the chance of catching a cold.