What Is Coumadin?

Coumadin is the brand name for the drug Warfarin. If you have your medication filled with the generic version, Warfarin or Warfarin Sodium will be on the label. These are the same drug. Coumadin is an anticoagulant (blood thinner). It reduces the formation of blood clots. It works by blocking the formation of certain clotting factors. Without these clotting factors, blood clots are unable to form.

How to Take Coumadin or Warfarin:

  • It is important to follow the directions you are given.
  • Let all doctors and dentists know you are on a blood thinner.
  • Because Coumadin dosages may change it is recommend that you use a pill box with sections for each day of the week to make sure you take the medication correctly.
  • You should be familiar with the number of tablets you take and the color, name brand and milligram strength.

Things that can interfere with Coumadin Therapy:

  • Food: Vegetables such as broccoli, collard greens, and spinach, are rich in vitamin K. These can cancel out the effects of Coumadin. We want you to eat healthy foods, but it is important to consume approximately the same amount of these foods on a daily/weekly basis. For example: If you usually do not eat leafy green vegetables, but decide to “eat healthy” and suddenly consume a lot of these types of foods, it can counteract the effects of Coumadin and cause your blood to clot more easily. Your lab tests help us to adjust your Coumadin dosage, so consistent diet helps by not causing unusual spikes or drops in your INR lab value.
  • Alcohol: We do not promote the use of alcohol with this drug; however, if you drink we ask that you limit your alcohol intake to 1 or 2 drinks each day.
  • Drugs: Please tell us about any medication changes, new drugs or drugs that your doctor has told you to stop taking. Drugs such as antibiotics, cholesterol and pain medications are especially important to us. Please let us know if you start or stop any of these medications. It is also important to let us know if you are taking any over the counter medications and/or herbal supplements (ginseng, ginkgo, kava, etc.) as some can interfere with Coumadin.

Lab Tests:

When you come to the clinic you will have a blood test called an INR (International Normalized Ratio). This checks your clotting times and we may adjust your dose of Coumadin based on this result. Low INR increases the risk of clots forming which can cause strokes, clots in the lungs (Pulmonary Embolism) and deep vein thrombosis (DVT). High INR levels cause you to be at risk of bleeding. This is why it is important to consistently monitor INR levels, so that adjustments can be made if necessary.

Side Effects:

Coumadin has some side effects. This drug will make you at risk for bleeding. A common side effect of the drug is bruising. It is important that you consistently make your scheduled appointments for INR testing so that dosage changes can be made if necessary. If you experience any of the following, seek immediate medical attention, go to the Emergency Room or call 911:

  • Prolonged bleeding from a cut or nosebleed
  • Urine is red or orange
  • Stool is black, tarry, or has red blood in it
  • If you vomit material that looks like wet coffee grounds

Clinic Reminders:

Please make all your scheduled appointments. If you cannot make an appointment, please call so we can reschedule your blood test. Bring ALL medication bottles to each visit. If you have any questions or concerns please feel free to call your clinic.


ARC Health Library: Warfarin Sodium

ARC Health Library: Vitamin K

Coumadin, Important Safety Points

So, You Need To Take Coumadin

Blood Thinner Pills: Your Guide to Using Them Safely

Pastillas que diluyen la sangre: Guía para su uso seguro


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This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.