The drug names of Betalock are Metoprolol Tartrate Tablets and Metoprolol Succinate Extended-Release Tablets. The side effects of the former include fatigue and dizziness, while the side effects of the latter include palpitations (rapid heartbeat, often accompanied by panic). 1. Metoprolol tartrate tablets are mainly used in the treatment of angina pectoris, hypertension, hypertrophic cardiomyopathy, myocardial infarction, arrhythmia, aortic coarctation, cardiac neurosis, hyperthyroidism, etc., and in recent years, they have also been used in the treatment of heart failure. Adverse effects of this product include dizziness, headache, fatigue, palpitations, chills in the extremities, vomiting, nausea, abdominal pain, diarrhea, chest pain, sleep disturbances, shortness of breath, tracheal spasm, excessive sweating, alopecia, thrombocytopenia, edema, fainting, tinnitus, and arthralgia. This product is contraindicated in patients with cardiogenic shock, sick sinus node syndrome, unstable decompensated heart failure, symptomatic bradycardia or hypotension, suspected acute myocardial infarction, severe peripheral vascular disease with risk of gangrene, hypersensitivity to any of the components of the product or to other beta-blockers, second-degree atrioventricular block, or third-degree atrioventricular block. 2. Metoprolol succinate extended-release tablets are mainly used for the treatment of angina pectoris, hypertension, stable chronic heart failure with abnormal left ventricular systolic function. The adverse reactions of this product include thrombocytopenia, depression, sleep disorder, hallucinations, anxiety, attention impairment, fatigue, headache, dizziness, taste changes, sensory abnormalities, visual impairment, tinnitus, palpitations, bradycardia, etc. The contraindications of this product are the same as those of Metoprolol Tartrate Tablets. It is recommended that patients go to regular hospitals in time when they feel unwell, and follow the doctor’s instructions for symptomatic treatment.