The main therapeutic drugs for phlegm but not cough are expectorants, such as nauseating and stimulating expectorants, phlegmolytics, and mucus regulators. In addition to symptomatic treatment, it is also necessary to clarify the causes of phlegm, and follow the doctor’s instructions to actively treat the cause. 1. Nauseating and stimulating expectorants: The use of expectorant drugs such as ammonium chloride and guaifenesin can stimulate the gastric mucosa to cause mild nausea, promote the increase of respiratory gland secretion, effectively dilute phlegm, and make phlegm easier to cough up. These drugs can cause gastrointestinal adverse reactions such as nausea and vomiting. 2. Phlegmolytics: Commonly used phlegmolytics include acetylcysteine, which can reduce the viscosity of phlegm, making it easier to cough up. The drug may cause cough, nausea, vomiting, bronchospasm and other adverse reactions. It is contraindicated in bronchial asthma. 3. Mucus regulator: This kind of expectorant mainly includes bromhexine, carbocysteine and so on. They can dissolve mucus and dilute the viscosity of sputum. These drugs may cause mild dizziness, nausea and stomach upset and other adverse reactions. Many drugs have the efficacy of phlegm expectorant effect, but they must be used in accordance with the indications of the drug, and to do so in accordance with the doctor’s instructions standardized use of drugs, not abuse. In addition to the need to clarify the cause of phlegm but not cough, such as chronic bronchitis, smoking, etc., in accordance with the doctor’s advice on the cause of the treatment or to change the bad habits.