Known brand names include Lopressor, Toprol, and Kapspargo.
A beta blocker that slows the heart and lowers blood pressure. It treats high blood pressure and angina, is used after a heart attack, and the extended-release form treats heart failure.
Metoprolol blocks beta-1 receptors, which let adrenaline speed up and strengthen the heartbeat. The heart then beats more slowly and with less force, and its electrical signal travels through it more slowly. Blood pressure falls, possibly because the heart pumps out less blood and the brain sends weaker stress signals to the body, though the exact cause is not known. In angina, a slower and gentler heartbeat means the heart needs less oxygen for the same effort.
Taken by mouth, it starts slowing the heart within an hour, and larger doses last longer. People may notice a slower pulse, tiredness, or dizziness, and too much slowing can lead to a very slow heartbeat or low blood pressure. At higher levels it also blocks beta-2 receptors in the airways and blood vessels, which is why it can tighten the airways in people with asthma. Because it blunts adrenaline, it can hide a racing heart, one of the warning signs of low blood sugar.
Metoprolol is a pill that lowers high blood pressure, and lower blood pressure cuts the risk of strokes and heart attacks. It also treats angina, a type of chest pain, over the long term, so attacks come less often and people can exercise longer. The extended-release form treats heart failure, where it lowers the chance of dying or being hospitalized.
It is taken by mouth, and for blood pressure it can be used alone or alongside other blood pressure medicines. After a heart attack, the immediate-release tablets help more people survive when their heart and blood pressure are stable. The immediate-release tablets have not been shown to be safe and effective in children. It controls these conditions without curing them, so people keep taking it even when they feel well.
Tiredness and dizziness are the most common complaints, and some people notice low mood, diarrhea, itching or rash, or shortness of breath. A slow pulse, low blood pressure, confusion, nightmares, and cold hands and feet can also happen. The label treats chest pain or a heart attack after stopping suddenly as dangerous, along with worsening heart failure, heart block, and airway spasm. It also warns that it can hide the warning signs of low blood sugar.