Theophylline extended-release tablets are usually taken after meals. Theophylline extended-release tablets are a long-acting theophylline drug, which has the effect of relaxing bronchial smooth muscle, counteracting the contraction and spasm of bronchial smooth muscle, improving the patient’s ventilation and ensuring the smooth flow of the airway. Some patients may experience some adverse reactions after taking this drug, the most common of which is gastrointestinal irritation, manifested as nausea, vomiting, or even abdominal pain, diarrhea, abdominal discomfort and other adverse reactions. Therefore, in clinical practice, it is recommended to take this drug after meals to reduce these gastrointestinal side effects to a certain extent. Because this drug is an extended-release agent with a relatively long duration of action, it is recommended to monitor the drug concentration when available and must be taken after meals.