Metoprolol succinate extended-release tablets are beta-blockers. Patients who take this drug after the weakness, need to determine whether it is due to the side effects of the drug or due to the inappropriate dose of the drug, this drug needs to follow the principle of gradual reduction of the amount of drugs, can not be discontinued without authorization, it is recommended that the patient informed the doctor, the doctor to make a judgment. Metoprolol succinate extended-release tablets are mainly used for the treatment of supraventricular tachyarrhythmia, lowering blood pressure, angina pectoris, coronary heart disease, chronic cardiac insufficiency. The common adverse reactions of this drug are diarrhea, nausea, insomnia, fatigue and so on. 1. Side effects of the drug: Metoprolol succinate extended-release tablets itself may cause dizziness and fatigue in the body of the person taking the drug. 2. Inappropriate dosage: If the dosage of the drug is too high or the body itself is too sensitive to the drug, it may cause the heart rate to slow down too fast and the blood pressure to drop too fast, which may lead to a decrease in the blood flow to the brain, a decrease in the heart rate, a relative decrease in the cardiac output, and so on, resulting in the patient experiencing dizziness and fatigue. The use of this drug needs to follow the principle of incremental increase and decremental decrease, and the drug should not be stopped at once. Patients should seek medical attention as soon as possible after the occurrence of adverse reactions, and adjust the dosage of the drug or stop using the drug after evaluation by a professional doctor, and should not use the drug arbitrarily, so as to avoid serious consequences.