Clinically, when using nebulized inhalation to treat respiratory diseases, the main drugs that can be chosen for expectorant are the following, such as amiloride, cysteine, chymotrypsin, etc. The common characteristics of these drugs are that they dilute sputum, promote sputum discharge, reduce the viscosity of sputum, and have the effect of promoting the movement of airway wall cilia. All these effects can promote the body’s sputum excretion and make the airway open. Clinically, it can be used for airway infections with thick and sticky sputum, such as acute bronchitis, acute attacks of chronic bronchitis and bronchial asthma combined with infections, bronchiectasis combined with severe infections and pneumonia, etc.