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Coumadin: What you need to know about this blood-thinning drug

Last Modified: 10/17/2019

Warfarin (Coumadin) prescription

Warfarin, better known by its brand name Coumadin®, is a prescription medication that interferes with normal blood clotting and is often referred to as “blood thinners”. If this medication is currently a part of your daily regimen, there are some things you need to know about its potential benefits and possible risks. We invited Yazan Salah, 2020 PharmD Candidate, Manchester University College of Pharmacy, and Stacy Clore, PharmD, BCPS, Parkview Health, to answer questions surrounding this popular prescription medication.

What is Coumadin?

Coumadin is a prescription medication, classified as an anticoagulant, that’s used to thin blood and help prevent blood clots from forming. Once blood clots are formed, they can potentially lead to severe conditions such as heart attack or stroke. That’s why it’s imperative to take Coumadin, if prescribed.

What are some of the main side effects associated with Coumadin?

The primary adverse effect of Coumadin is bleeding. Bleeding can be further broken down into minor and major bleeding. Examples of minor bleeding would include bleeding while brushing teeth or as a result of shaving. Examples of major bleeding include a nose bleed or bleeding that doesn’t stop after 5-10 minutes of pressure, or blood in the urine or stool. It’s important to seek immediate medical attention for any major bleeding.

What should a patient monitor while on Coumadin?

While on Coumadin, it is important to monitor the International Normalized Ratio (INR). INR is a regular blood test that indicates if the blood is too thick or too thin. A normal INR of 1.0 is seen in patients who do not take Coumadin. A typical INR goal for a patient taking Coumadin is 2-3; however, this goal may vary based on why the patient is taking the medication. If the INR is above the goal range, the blood is too thin and there is a higher risk for bleeding. If the INR is below the goal range, the blood is too thick and the chance for clotting is increased.

Coumadin dosing is tailored specifically to each individual patient and is adjusted according to the INR results. When starting Coumadin therapy, the INR is checked frequently, approximately 1-2 times per week, until the proper dose is established, and the INR is stable. Once the INR is stable, less appointments are needed.

Are there any potential interactions patients should be aware of?

Unfortunately, many medications, supplements and even food can affect how Coumadin functions. It is important to take precautions with the following:

  • Diet - specifically foods high in vitamin K, like green leafy vegetables, broccoli, Brussels sprouts, kale, lettuce and spinach. These foods do not need to be avoided while on Coumadin if your diet is consistent regarding vitamin K intake. If there has been a change in diet it is best to inform your healthcare provider.
  • Herbals/over-the-counter products and medications - It is recommended to avoid nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen and naproxen, while on Coumadin due to the increased risk for bleeding. Tylenol (acetaminophen) is the recommended OTC medication for pain while on Coumadin. Always let your healthcare provider know about any medication changes, even if it is an OTC medication or an herbal product; many medications can counteract with Coumadin.
  • Alcohol - It is also recommended to avoid alcohol while on Coumadin.
Who should avoid Coumadin?

Coumadin is not recommended for those who have a high risk of bleeding complications, are pregnant or have an allergy to Coumadin or any of its ingredients.

What do I do if I miss a dose?

Take a missed dose as soon as you think about it on the same day you missed the dose. If it’s the next day or close to your next dose, skip the missed dose and go back to your normal routine. Do not take two doses at the same time or extra doses to make up for missed medication. It is imperative that you do not take more than one dose of Coumadin in the same day.

What other information should I keep in mind when taking Coumadin?

Coumadin is available in many different tablet strengths and colors. When picking up your prescription, always double check that the color of your medication is the same color you have received previously.  It’s also highly recommended to take Coumadin at the same time every day (usually in the evening) with or without food.

Lastly, do not stop or start any medications without first talking to your doctor. For any questions or concerns, call your local Anticoagulation (ATU) Clinic, your physician’s office or your pharmacist.

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