There are many kinds of medicines for expectorant and phlegm, mainly including phlegm dissolvers, mucus regulators, phlegm thinner, enzymes, etc. The specific medication should be in accordance with the doctor’s prescription. 1. Phlegm dissolvers: they can decompose the viscous components of phlegm, liquefy phlegm, reduce the viscosity of phlegm, and thus facilitate phlegm coughing out. Representative drugs are acetylcysteine, aminoglutethimide and so on. 2. Mucus regulator: It can regulate the viscosity of sputum, thus diluting the effect of sputum and promoting the discharge of sputum. The representative drugs are Bromhexine Hydrochloride, Ambroxol Hydrochloride, Carbocistein, Erdostein. 3. Sputum-thinning drugs: by stimulating the gastric mucosa, reflexively promote the secretion of respiratory glands to increase, and then play a role in diluting sputum, which is conducive to the discharge of sputum. The representative drugs are ammonium chloride, guaiac glycerol ether and so on. 4. Enzymes: such as chymotrypsin, commonly used in nebulizing phlegm. The application of expectorant drugs should be selected and applied under the guidance of a doctor, and should not be taken blindly by oneself.