Low immunity is the main reason for frequent colds and runny nose. Colds are generally caused by viral infections of the upper respiratory tract, which can lead to nasal congestion, runny nose, sneezing, coughing and other symptoms. Although the onset of colds is not limited to age and gender, people with low immunity are more susceptible to colds, such as the elderly, infants and young children with immune systems that are not mature enough, and people with underlying medical conditions, all of which are caused by the inability of the immune system to effectively defend against viral invasions, ultimately leading to frequent colds and runny noses. Colds are a self-limiting disease, and the runny nose and other symptoms caused by the disease will disappear as the disease heals itself. It is recommended to have balanced nutrition and exercise to improve one’s physical fitness, enhance one’s immunity and resistance, and reduce the chances of catching a cold.