There is a difference between taking theophylline extended-release tablets before and after meals, and it is usually chosen to be taken after meals. Theophylline extended-release tablets are a kind of long-acting theophylline drugs, which have the function of relieving airway smooth muscle spasm and enhancing diaphragm contraction, and by counteracting the contraction and spasm of bronchial smooth muscle, they can effectively improve the ventilation of patients and ensure that their airways are smooth. Some patients will have some adverse reactions after taking theophylline extended-release tablets, the more common is the stimulation of the gastrointestinal tract, nausea, vomiting, abdominal pain, diarrhea and other adverse reactions, gastrointestinal tract stimulation is aggravated by eating before meals, therefore, it is clinically recommended to take it after meals, which can alleviate the gastrointestinal side effects to some extent. Note that this product should not be used in patients with persistent asthma or spasmodic attacks of acute bronchitis, and patients should be closely monitored for blood concentration during administration.