Metoprolol is in a class of medications called beta blockers. It works by relaxing blood vessels and slowing heart rate to improve blood flow and decrease blood pressure. Overview: Metoprolol is a beta blocker. It is is used to treat high blood pressure, chest pain, heart failure, and lower the risk of a repeat heart attack. Common side effects include tiredness. Metoprolol is used alone or together with other medicines to treat high blood pressure (hypertension). High blood pressure adds to the workload of the heart and arteries. If it continues for a long time, the heart and arteries may not function properly. Metoprolol succinate is a once-daily, extended-release beta-blocker used to treat high blood pressure, angina, and heart failure. It lowers cardiovascular risk, improves exercise tolerance, and reduces hospitalizations. Metoprolol is used to treat angina (chest pain) and hypertension (high blood pressure). Learn about side effects, interactions and indications. Read on to learn about the side effects of metoprolol, including common, severe, and long-term side effects, and how to manage them. The specific agent in on-market formulations of metoprolol is either metoprolol tartrate or metoprolol succinate, where tartrate is an immediate-release formulation and the succinate is an extended-release formulation (with 100 mg metoprolol tartrate corresponding to 95 mg metoprolol succinate). Toprol XL (Metoprolol Succinate) may treat, side effects, dosage, drug interactions, warnings, patient labeling, reviews, and related medications including drug comparison and health resources. Metoprolol is a prescription medication used to treat the symptoms of Hypertension, Acute Myocardial Infarction, Congestive Heart Failure, Angina. Learn about side effects, dosages, drug interactions, and more. 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.