It is useful to drink salt water for cough. Cough is mainly due to the decrease in the body’s resistance to the invasion of pathogens, and the inflammatory changes in the mucous membrane of the respiratory tract, such as congestion, edema and exudation of inflammatory substances, most commonly upper respiratory tract infections, pharyngitis, bronchitis, pneumonia, etc. Saline is a solution containing a certain concentration of sodium chloride, after local use, such as gargling, gargling throat, can reduce the degree of mucosal congestion and edema in the throat, can relieve cough and other symptoms of pharyngeal discomfort. And the sodium ions contained in the salt water itself have certain effects of inhibiting germs and anti-inflammatory and resisting pathogens. So drinking some salt water is good for relieving the symptoms of cough caused by cold, bronchitis, pneumonia, etc.