Blood thinners are medicines that help blood flow smoothly through your veins and arteries. They also keep blood clots from forming or getting bigger. They’re used to treat some types of heart disease and heart defects, and other conditions that could raise your risk of getting dangerous clots.
They can protect against heart attacks and strokes. But they also come with risks: For example, they’ll cause you to bleed more than usual when you cut yourself.
The greatest danger from deep vein thrombosis (DVT) is that the clot will break loose, travel through your blood, and damage an organ.
"The place it gets stuck most commonly is the lungs, and that's called a pulmonary embolism (PE)," says Molly Cooke, MD, of the University of California, San Francisco. Less often, another clot can form and travel to the brain and cause a stroke. If a clot travels to the heart, it could cause a heart attack. A clot in the kidneys can cause kidney failure.
The lifesaving benefits of these drugs often outweigh the potential dangers. Still, it's important to learn about both before you start taking them.
Types of Blood Thinners
There are two. The first is called anticoagulants. These keep your blood from clotting, or turning into solid clumps of cells that stick together. Most come in pill form. Some popular ones in this category include:
Other, more powerful types of this blood thinner are given as a shot or through an IV, either in the hospital or at home. Some of the more well-known ones are heparin and fondaparinux.
The second class of blood thinners is called antiplatelets. These target tiny particles in the blood called platelets. They come in pill form, and include:
How They Work
Blood thinners don’t actually make your blood thinner. Nor can they break up clots. But they do keep blood from getting thicker and forming new clots. They can also slow the growth of existing ones.
Some anticoagulants do this by removing vitamin K from the liver. Your body needs this to make proteins called clotting factors. These help blood cells and platelets (tiny pieces of blood cells) bind together.
Antiplatelets keep platelets from sticking to each other and to the walls of blood vessels. These drugs are weaker than anticoagulants. They’re often prescribed to people at risk for future blood clots, rather than to treat existing ones.
Who Needs Them?
About 2 million to 3 million people take blood thinners every year. You may need them if you’ve already had a heart attack or a stroke, since they can lower your risk of having a second one.