Drugs with the effect of diluting sputum, commonly used sputum thinner such as guaiacol bromine oral solution; mucolytic agent such as acetylcysteine; mucus regulator such as ambroxol, carbocysteine. 1. Sputum thinner: commonly used drugs in the clinic are guaiacol bromine oral solution, this drug can increase the secretion of respiratory glands, so as to make sputum diluted, easy to cough out. Possible adverse reactions to this drug are abdominal distension, nausea, vomiting, dizziness, palpitations, skin rash, etc. Occasionally, transient transaminase elevation, which can disappear after stopping the drug. Women within 3 months of pregnancy, children under 2 years of age and patients with pulmonary hemorrhage are prohibited. 2. Mucolytic agent: it can decompose the viscous components in sputum, reduce the viscosity of sputum, and thus facilitate the coughing out of sputum. The representative drugs are acetylcysteine granules and acetylcysteine solution for inhalation. Some patients may have adverse reactions such as nausea, vomiting, runny nose, gastritis. Occasionally may cause hemoptysis. Asthma patients and children under 2 years old are prohibited. 3. Mucus regulator: the representative drugs are aminobromine hydrochloride capsules, carbocysteine tablets and so on. These drugs mainly act on the secretion of bronchial glands, which can make sputum less viscous and easy to cough out. Possible adverse effects of the drug are occasional rash, stomach upset, abdominal pain, diarrhea, dizziness, headache, etc. In severe cases, anaphylaxis may occur. Ambroxol hydrochloride capsules are contraindicated in women during the first 3 months of pregnancy and in those who are allergic to the drug. Carbocisteine tablets are contraindicated in patients with active peptic ulcers. The above drugs should be taken under the guidance of a doctor, if you are taking other drugs at the same time should be informed to the doctor or pharmacist in advance, do not blindly use their own medication.