This article begins by describing what blood thinners and anticoagulants are in general and how they are used to prevent or treat stroke. The following sections go into detail about specific medications and how they are used. Click on the name of any drug below to skip directly to that section, or just scroll down to start reading from the beginning.
- Antiplatelet medications
- Low Molecular Weight Heparin (LMWH)
- Warfarin (Coumadin)
What are blood thinners?
Blood thinners (anticoagulants) are medications that keep new blood clots from forming and existing clots from growing. Clots are lumps of thickened blood that form when the blood hardens from liquid to solid. When clots form in blood vessels in the brain they can restrict or stop the flow of blood, causing a blocked-vessel (ischemic) stroke. Blood thinners reduce the risk of blocked-vessel stroke by reducing the risk of blood clots.
How are blood thinners used to prevent and treat stroke?
If you have had a blocked-vessel (ischemic) stroke or TIA, you may be given blood thinners for the first few days to prevent blood clotting complications, especially if you have other conditions (such as atrial fibrillation) that make clots more likely to form.1 Blood thinners can increase the risk of dangerous bleeding, including bleeding in the brain, and they do not reduce the chances of dying or having a disability from a stroke, so they are not used routinely in all stroke patients.1, 2 If someone who has had a stroke is having difficulty moving or walking, blood thinners may be given to prevent the development of clots in the veins in your lower legs (deep vein thrombosis) or in the lungs.
Blood thinners are not used to prevent a stroke in patients who have never had a stroke unless you have other conditions that put you at high risk of having problems caused by blood clots, such as replacement heart valves, atrial fibrillation, or a history of blood clotting problems.1, 3
You should not receive blood thinners if you have a bleeding (hemorrhagic) stroke because they increase your chances of dangerous bleeding and can make this kind of stroke even worse.2 Blood thinners should not be used within 24 hours of treatment with tPA.