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. 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. Learn about the side effects of metoprolol, from common to rare, for consumers and healthcare professionals. 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 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 beta blocker that works best to lower blood pressure when combined with dietary and lifestyle changes. Taking metoprolol with food is recommended to increase its absorption, particularly with short-acting tablets. Read on to learn about the side effects of metoprolol, including common, severe, and long-term side effects, and how to manage them. 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 (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.