Metoprolol is a beta1 receptor antagonist and is often used clinically to treat hypertension, chronic heart failure, and coronary angina pectoris. Metoprolol should be given in the morning on an empty stomach to achieve a better therapeutic effect. Most patients with hypertension have blood pressure that starts to rise in the early morning after waking up, and the blood pressure is high during the day but not at night, so taking metoprolol in the early morning on an empty stomach can reduce the rise in blood pressure after waking up in the early morning as well as the rise in blood pressure during the day. For patients with chronic heart failure and coronary angina, due to sympathetic excitation in the morning, heart rate will be accelerated and myocardial oxygen consumption will be increased, so taking metoprolol in the early morning on an empty stomach can inhibit sympathetic excitability, slow down heart rate and reduce myocardial oxygen consumption, so as to achieve better therapeutic effect.