Patient education: Choosing an oral medicine for blood clots (The Basics)

What is a blood clot? — Normally, your body is protected from bleeding because your blood vessels seal over after an injury. The seal is made by proteins and cells in the blood. The seal that forms is called a clot. It can be small or large depending on the size of the injury.

Sometimes, the blood proteins and cells form a clot inside a blood vessel when there is no injury. If the clot is large, it can cause a blockage and stop the blood from flowing.

●Most often, this happens in the veins in the leg. This is called a "deep vein thrombosis" ("DVT"). It can cause swelling in the leg or in another part of the body.

●These blood clots can also break off and travel in the bloodstream to another part of the body, like the lungs. This is called a "pulmonary embolism" ("PE"). If a PE is large, it can make you pass out or stop breathing.

●Dangerous blood clots can also form in other parts of the body like the heart or the brain. The risk of blood clots in the heart is high in people who have a heart rhythm problem called "atrial fibrillation" ("A-fib").

Medicines used for blood clots are also known as "anticoagulants" or "blood thinners." They do not actually thin the blood. They just make the blood less likely to form clots.

What are the different oral medicines for blood clots? — "Oral" means that the medicine is taken by mouth. There are several medicines for blood clots that come as pills or capsules. They include:

●Apixaban (brand name: Eliquis)

●Dabigatran (brand name: Pradaxa)

●Edoxaban (brand names: Savaysa, Lixiana)

●Rivaroxaban (brand name: Xarelto)

●Warfarin (brand name: Jantoven, also known as Coumadin in some places)

Are there other types of medicines for blood clots? — Yes. In some situations, your doctor might prescribe medicine that comes as an injection (shot) instead of a pill. Examples include:

●"Low molecular weight heparins" such as enoxaparin (brand name: Lovenox) and dalteparin (brand name: Fragmin)

●Fondaparinux (brand name: Arixtra)

Why would I need one of these medicines? — The main reason doctors prescribe these medicines is to prevent blood clots or to treat clots that have already formed. They do not dissolve the clots, but they prevent them from getting bigger.

Doctors prescribe these medicines to prevent blood clots in:

●People who have A-fib – The medicine helps lower the chances of forming a blood clot in the heart. A blood clot in the heart can travel to the brain and cause a stroke.

●People who have had surgery – The medicine helps prevent a blood clot in the legs (DVT). A DVT can travel to the lungs and cause a PE. If this happens, it can cause trouble breathing.

Preventing blood clots is especially important after certain surgeries, like hip or knee replacement, or in people with cancer. But blood clots can happen after many types of surgery.

●People who have a mechanical (metal) heart valve – The medicine helps lower the chances of forming a blood clot in the heart. If this happens, the clot could travel to the brain and cause a stroke.

●Other people who are at high risk of having a blood clot

Nothing can completely prevent all blood clots. But these medicines can make clots less likely to form.

Doctors also prescribe these medicines for people who have already had a clot, to stop it from getting worse. This includes:

●People who have had a stroke related to A-fib

●People who have had a DVT or PE for any reason

●People who have had a blood clot in another part of the body

How do these medicines help? — These medicines do not dissolve clots. But they:

●Keep clots from growing bigger

●Help prevent new clots from forming

What are the differences among these medicines? — There are many differences. These include how often you take the medicine, whether you need to change your diet, which other medicines might affect how it works, and whether you need regular blood tests.

The table answers some common questions about the differences between the oral medicines (table 1). Some of the main differences include:

●What are they used for – Most people with a DVT, PE, or A-fib can take any of these medicines. For people with certain conditions, warfarin is safer and more likely to prevent blood clots. Conditions best treated with warfarin include:

•Mechanical heart valve

•Antiphospholipid syndrome – This is a clotting disorder that can cause DVT, PE, heart attacks, and strokes.

●How often you take the pills – This depends on which medicine you take and why your doctor prescribed it.

•Warfarin, edoxaban, and rivaroxaban are taken once a day. If you have a blood clot, rivaroxaban is taken twice a day for the first 3 weeks, and some people with heart disease take a low dose of rivaroxaban twice a day.

•Apixaban and dabigatran are usually taken twice a day. If you are taking the pills to treat a new blood clot, the first week or more of treatment might be different.

Your doctor, nurse, or pharmacist will tell you how many times you need to take your medicine each day.

●Whether you need to change your diet – Warfarin blocks vitamin K, so if you take warfarin, it is important to get about the same amount of vitamin K each day. Different foods have different amounts of vitamin K (table 2).

●Whether you need regular blood tests – If you take apixaban, dabigatran, edoxaban, or rivaroxaban, you do not need regular blood tests. But you might need a blood test to check your kidney and liver function once in a while.

If you take warfarin, you need to get your blood tested regularly to check how it is clotting. This test is called "PT and INR." This is important to make sure that you are always getting the dose you need.

●The risk of bleeding – Most kinds of bleeding (including bleeding in the brain) are less likely with apixaban, dabigatran, edoxaban, and rivaroxaban than they are with warfarin. But all of these medicines raise your risk of bleeding. This can be serious internal bleeding, like bleeding in the brain or the intestines, or external bleeding, like after you get a cut.

●What happens if I miss a dose – If you miss a dose of apixaban, dabigatran, edoxaban, or rivaroxaban, you might not be as well protected from blood clots because these medicines leave your system quickly. If you miss 1 dose of warfarin, it will still be in your system. Ask your doctor or pharmacist what to do if you miss a dose of your medicine.

●Whether you can take them while pregnant – These medicines are generally not considered safe during pregnancy. Most people who are taking one of these medicines and get pregnant are switched to a different medicine that is given as an injection. Talk to your doctor or nurse if you want to get pregnant or find out that you are pregnant. Do not stop taking your medicine, as this could increase your risk of blood clots.

Which medicine is right for me? — Your doctor will talk to you about your condition, options, and preferences. Many people prefer one of the pills that does not require regular blood tests. For other people, warfarin is the best choice. This includes people with a mechanical heart valve or who have antiphospholipid syndrome.

For more detailed information about your medicines, ask your doctor or pharmacist for the patient handout from Lexicomp available through UpToDate. It explains how to use each medicine, describes its possible side effects, and lists other medicines or foods that can affect how it works.

More on this topic

Patient education: Taking oral medicines for blood clots (The Basics)
Patient education: Stroke (The Basics)
Patient education: Deep vein thrombosis (blood clot in the leg) (The Basics)
Patient education: Pulmonary embolism (blood clot in the lung) (The Basics)
Patient education: Atrial fibrillation (The Basics)
Patient education: Medicines for atrial fibrillation (The Basics)
Patient education: Prosthetic valves (The Basics)
Patient education: Prothrombin time and INR (PT/INR) (The Basics)
Patient education: Warfarin and your diet (The Basics)
Patient education: Lowering the risk of a blood clot (The Basics)

Patient education: Warfarin (Beyond the Basics)
Patient education: Deep vein thrombosis (DVT) (Beyond the Basics)
Patient education: Pulmonary embolism (Beyond the Basics)