Metoprolol is a beta-blocker medication used to treat high blood pressure, chest pain (angina), and heart failure, and to improve survival after a heart attack. 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 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. Get more information about metoprolol, include how it works, what it can be used for, and what to expect when taking the medication. 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, sold under the brand names Lopressor and Toprol-XL among others, is a medication used to treat angina, high blood pressure and a number of conditions involving an abnormally fast heart rate. [5] 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. Read on to learn about the side effects of metoprolol, including common, severe, and long-term side effects, and how to manage them. 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. Learn about the side effects of metoprolol, from common to rare, for consumers and healthcare professionals.