What Are Anticoagulants and Antiplatelet Agents?

Updated:Dec 8,2015

Anticoagulants and antiplatelet agents are medicines that reduce blood clotting in an artery, a vein or the heart. Blood clots can block the blood flow to your heart muscle and cause a heart attack. They can also block blood flow to your brain, causing a stroke.

What should I know about anticoagulants?

Anticoagulants (sometimes known as "blood thinners" are drugs that can prevent your blood from clotting or prevent existing clots from getting larger. They can keep harmful clots from forming in your heart, veins or arteries. Clots can block blood flow and cause a heart attack or stroke.

  • Examples are heparin, warfarin, dabigitran, apixaban, and rivoraxaban.
  • You must take anticoagulants just the way your doctor tells you.
  • Regular blood tests tell your doctor how the anticoagulants are working.
  • You must tell other doctors and dentists that you’re taking anticoagulants.
  • Never take aspirin with anticoagulants unless your doctor tells you to.
  • Ask your doctor before taking anything else — such as vitamins, cold medicine, sleeping pills or antibiotics. These can make anticoagulants stronger or weaker, which can be dangerous.
  • Tell your family how you take them and carry an emergency medical ID card.

Could anticoagulants cause problems?

If you do as your doctor tells you, there probably won’t be problems. But you must tell your doctor right away if:

  • Your urine turns red or dark brown.
  • Your stools turn red, dark brown or black.
  • You bleed more than normal when you have your period.
  • Your gums bleed.
  • You have a very bad headache or stomach pain that doesn’t go away.
  • You get sick or feel weak, faint or dizzy.
  • You think you’re pregnant.
  • You often find bruises or blood blisters.
  • You have an accident of any kind.

What should I know about antiplatelet agents?

These drugs, such as aspirin, keep blood clots from forming. Many doctors now prescribe aspirin to heart patients for this reason.

Aspirin can save your life if you have heart problems. You don’t need a prescription to get it, but it’s just as important as any other medicine your doctor tells you to take. You must use it just as you’re told.


  • Helps keep blood from clotting.
  • Has been shown to reduce the risk of a heart attack, stroke or TIA in certain patients.
  • Should not be taken with anticoagulants unless your doctor tells you to.
  • Must be used as your doctor orders — most often in small doses every day or every other day if you already have cardiovascular disease (CVD) or are at high risk for CVD.
  • Might not be taken while you’re having surgery.

Do I need to wear an emergency medical ID?

Yes, always keep it with you. Wear it – on your person or keep it in your purse or wallet. It needs to include:

  • The name of the drug you’re taking.
  • Your name, phone number and address.
  • The name, address and phone number of your doctor.
How can I learn more?
  1. Call 1-800-AHA-USA1 (1-800-242-8721), or visit heart.org to learn more about heart disease and stroke.
  2. Sign up to get Heart Insight, a free magazine for heart patients and their families, at heartinsight.org.
  3. Connect with others sharing similar journeys with heart disease and stroke by joining our Support Network at heart.org/supportnetwork.
We have many other fact sheets to help you make healthier choices to reduce your risk, manage disease or care for a loved one. Visit heart.org/answersbyheart to learn more.

Do you have questions or comments for your doctor or nurse?

Take a few minutes to write your own questions for the next time you see your healthcare provider. For example:

What kind of aspirin should I take, and what is the right dose for me?

©2015, American Heart Association


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