Acetylcysteine is an expectorant, which can liquefy phlegm and make it easy to cough up, and promote the recovery of the disease. Acetylcysteine nebulizer has the effect of regulating mucus, often used in clinical practice to help patients cough up sputum, reduce the viscosity of sputum, mainly used in the treatment of respiratory diseases such as bronchitis, chronic obstructive pulmonary disease and bronchiectasis caused by phlegm viscous and not easy to cough up symptoms. Patients need to follow the doctor’s instructions to use, can not be arbitrary use of the drug, the use of the drug process may appear rash, wheezing, dyspnea and other adverse reactions. If the patient is intolerant should immediately follow the doctor’s instructions to stop the drug, bronchial asthma patients are prohibited from using the drug, lactating women, pregnancy, infants and young children should be careful to use the drug.