Theophylline extended-release tablets can relax the smooth muscle of the respiratory tract and dilate the bronchial tubes. Theophylline extended-release tablets its main effect is to dilate the bronchial tubes, diastolic smooth muscle of the bronchial tubes, so as to achieve the efficacy of antispasmodic and asthma. It is often used in the treatment of patients with bronchial asthma, obstructive emphysema, wheezing bronchitis, cough variant asthma. However, it should be noted that the drug is contraindicated in patients with hypersensitivity to the drug, active peptic ulcers and uncontrolled convulsive diseases. The drug is not indicated for patients with persistent asthma or acute bronchospasm attacks. Adverse reactions such as nausea, vomiting, cardiac arrhythmias, irritability may occur during the use of the drug. Therefore, the drug needs to be used under the supervision of a doctor, and blind self-medication should be avoided to avoid adverse reactions.