Theophylline can cause hypokalemia. Theophylline is a class of methylxanthine derivatives, with asthma, cardiotonic, diuretic and vasodilator effects, through the inhibition of phosphodiesterase, so that the intracellular cAMP level increases and diastolic bronchial smooth muscle, and increase the release of endogenous catecholamines, but also inhibit phosphodiesterase and enhance the activity of Na +-K +-ATPase, resulting in hypokalemia. In addition, theophylline’s therapeutic window is narrow, adverse reactions are closely related to its blood concentration, early nausea, vomiting, agitation, insomnia and other symptoms, when the serum concentration of more than 20 μg / ml, tachycardia, cardiac arrhythmia, when theophylline more than 40 μg / ml, fever, convulsions and other symptoms, even severe respiratory and cardiac arrest and death. It should be noted that patients who are allergic to the product, active peptic ulcers and patients with uncontrolled convulsive diseases are prohibited. If you need to use theophylline drugs, patients should follow the doctor’s instructions for medication, avoid self-medication, the treatment process, such as the occurrence of adverse reactions, should be promptly communicated with the doctor in a timely manner, so as not to delay the condition.