Metoprolol tartrate comes as an oral tablet. Metoprolol succinate comes as an extended-release (ER) oral tablet. Metoprolol oral tablets are available as the brand-name drugs Lopressor and Toprol XL. Metoprolol is used to treat angina (chest pain) and hypertension (high blood pressure). Learn about side effects, interactions and indications. Metoprolol may worsen the symptoms of heart failure in some patients. Check with your doctor right away if you are having chest pain or discomfort, dilated neck veins, extreme fatigue, irregular breathing or heartbeat, swelling of the face, fingers, feet, or lower legs, trouble breathing, or weight gain. Metoprolol (Lopressor®) is a medication that lowers your blood pressure and heart rate, making it easier for your heart to pump blood to the rest of your body. Metoprolol is used for a number of conditions, including angina, acute myocardial infarction, high blood pressure, supraventricular tachycardia, ventricular tachycardia, congestive heart failure, and prevention of migraine headaches. [5] It is an adjunct in the treatment of hyperthyroidism. [18] Both oral and intravenous forms of metoprolol are available for administration. [19] The different. Metoprolol tartrate is a β1-selective adrenergic blocking agent (β-blocker). Lopressor (Metoprolol Tartrate) may treat, side effects, dosage, drug interactions, warnings, patient labeling, reviews, and related medications including drug comparison and health resources. Read on to learn about the side effects of metoprolol, including common, severe, and long-term side effects, and how to manage them. Find patient medical information for Metoprolol (Lopressor, Toprol XL, others) on WebMD including its uses, side effects and safety, interactions, pictures, warnings, and user ratings Learn how metoprolol works in your body and how long it stays in your system, plus dosing schedules for different conditions.