The statement of “three common nebulized drugs” is inaccurate, because the common nebulized inhalation drugs in clinical practice include four major categories, namely glucocorticoids, phlegmolytic drugs, β2 agonists and anticholinergic drugs. Among them, glucocorticoids, as the most effective anti-inflammatory drugs, have relatively few adverse reactions and are also the drugs of choice for long-term treatment of asthma; phlegmolytic drugs mainly make sputum lysis and dilution to facilitate sputum discharge; β2 agonists and anticholinergic drugs are bronchodilators, mainly to release bronchospasm. I. Glucocorticoids: 1. Budesonide for inhalation: rapid onset of action, 10-30 minutes to play the airway anti-inflammatory effect, suitable for the treatment of acute attacks of severe bronchial asthma. Adverse reactions are common hoarseness, ulcers, dry mouth, cough, and oral candidiasis may also occur in patients who have used budesonide for a longer period of time, and it should be noted that it should be used with caution in patients with tuberculosis. 2. dexamethasone: dexamethasone has larger particles after inhalation, with large water solubility, in which there is no lipophilic gene, and low affinity for glucocorticoid receptors, and less binding to airway mucosal tissues, resulting in low deposition rate in the lung, which in turn plays local anti-inflammatory effect. However, dexamethasone has a long half-life and tends to accumulate in the body and inhibit the subthalamic-pituitary-adrenal axis, so it is not recommended. Second, phlegmolytic drugs: mainly include acetylcysteine solution for inhalation and aminoglutethimide hydrochloride injection, which can promote the discharge of phlegm in patients with a lot of sputum and sticky sputum that is difficult to be discharged. β2 agonists: 1, short-acting drugs: common salbutamol, terbutaline, etc. Salbutamol has a faster onset of action and stronger tracheal diastolic effect than terbutaline, so it is often used as the drug of choice to relieve the symptoms of acute asthma attacks; 2, long-acting drugs: long-acting drugs are divided into fast-acting formoterol, which takes effect within a few minutes, and slow-acting salmeterol, which takes effect in half an hour. β2 agonists can have an effect on the heart muscle and skeletal muscle. Therefore, they should be used with caution in patients with organic heart disease, hypertension, hyperthyroidism and pregnancy. Anticholinergic drugs: The commonly used drug is ipratropium bromide solution for inhalation, which can diastole the bronchial tubes. Adverse reactions include headache, nausea, dry mouth, palpitations, gastrointestinal motility disorders, increased intraocular pressure, etc. Therefore, it should be used with caution in patients with angle-closure glaucoma and in patients during pregnancy and lactation.