Acetylcysteine solution may refer to acetylcysteine injection or acetylcysteine solution for inhalation; the former is mainly used for the treatment of early stage liver failure, while the latter is mainly used for expectorant effects. Acetylcysteine injection is mainly used in the early stages of liver failure to reduce bilirubin levels and increase plasminogen activity. It may also cause adverse reactions such as nausea, increased heart rate, leukopenia or allergic reactions. It needs to be contraindicated in people who are allergic to the product and used with caution in people who have a history of asthma or who have gastric ulcers. Inhalation acetylcysteine solution can be applied to cough and sputum symptoms caused by chronic obstructive pulmonary disease, pneumonia and other related diseases, can dilute sputum and promote phlegm expectoration. It can also lead to gastrointestinal reactions allergies and other adverse reactions, allergic to the product is a contraindication. Drugs must be used under the guidance of a doctor, do not self-medication.