Dextromethorphan is a central cough suppressant, which is widely used in clinical practice. It is similar to codeine phosphate in its cough suppressant effect, but has no analgesic or hypnotic effect, has no inhibitory effect on the respiratory center, and does not produce dependence or tolerance, but produces central anesthetic effects when taken in high doses. The common clinical practice is to take 15-30 mg orally three times a day. For the application of cough suppressants, the clinical concern is that they are often used in patients with a strong dry cough. For patients with a cough with a lot of sputum or airway secretions that cannot be easily drained, the use of cough suppressants is not suitable, and active anti-inflammatory and phlegm reduction is needed to keep the airway open. For the simple use of cough suppressants, which may not be conducive to the drainage of airway secretions such as sputum or the control of inflammation, they need to be used reasonably under the guidance of a doctor.