Theophylline Extended-Release Tablets function mainly to relieve wheezing symptoms caused by bronchial asthma, wheezing bronchitis, obstructive emphysema, and heart failure. The main ingredient of Theophylline Extended-Release Tablets is theophylline. The drug has a direct relaxing effect on the smooth muscle of the respiratory tract, while theophylline enhances the diaphragm contraction force, which is beneficial to improve respiratory function. In clinical practice, it is mainly used for bronchial asthma, wheezing bronchitis, obstructive emphysema and other relief of wheezing symptoms, but also for wheezing in heart failure. When taking Theophylline Extended-Release Tablets, adverse reactions such as nausea, agitation, insomnia, tachycardia, arrhythmia, fever, and dehydration may occur, and in severe cases, may lead to the patient’s death due to respiratory and cardiac arrest. It should also be noted that theophylline extended-release tablets should not be used by patients who are allergic to the drug, or those with active peptic ulcers and uncontrolled convulsive disorders. Patients are advised to strictly follow their doctor’s instructions when using theophylline extended-release tablets to avoid delays or adverse consequences of improper use of the drug.