The most common side effects of taking theophylline tablets in general are nausea, vomiting, easy agitation, irritability and even insomnia in the early stage, tachycardia and arrhythmia may occur in the later stage, symptoms of hyperthermia, dehydration and convulsions may occur, and in more serious cases, sudden death due to respiratory and cardiac arrest may occur. Because the serum drug concentration of theophylline tablet treatment is very close to the toxic concentration, it is mainly used for the treatment of bronchial asthma, wheezing bronchitis and the relief of wheezing and shortness of breath caused by chronic obstructive pulmonary and cardiogenic asthma.