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Warfarin (Coumadin): an Overview

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Blood Clots  related image Photo: Getty Images

If you’ve been diagnosed with atrial fibrillation, then it’s possible that your doctor may prescribe warfarin to help prevent blood clots from forming. Blood clots form for a number of reasons, but they tend to be common among those with heart conditions such as atrial fibrillation. Left untreated, blood clots can lead to heart attack, stroke, and even death.

Warfarin, also known as Coumadin or Jantoven, is the most commonly used anticoagulant drug used to help prevent blood clots. It’s generally prescribed to those with:

• blood clots near the heart (may result in heart attack)
• blood clots in or near the lungs (may result in pulmonary embolism)
• blood clots anywhere in your body (venous thrombosis)
• a history of hearts arrhythmias, atrial fibrillation, or other heart abnormalities
• a risk of stroke

Warfarin is often referred to as a “blood-thinner” which is a misconception. The drug doesn’t thin the blood. Instead, it operates by limiting or reducing the body’s ability to form blood clots.

For many, warfarin can be a life-saving drug. But along with its powerful health benefits, it also has some dangerous side-effects and interactions that you should be aware of when taking it. According to the Mayo Clinic, some of the side effects of warfarin usage include feeling cold, fatigue, pale skin, food taste changes, hair loss, and gas. While bothersome, these side effects are not life threatening. Some side effects, however, are more serious and require immediate treatment by trained medical professionals:

• excessive bleeding (includes bleeding from rectum and black stools which may indicate internal bleeding)
• chest pain
• numbness
• difficulty moving
• muscle/joint aches
• hives, a rash or itching
• swelling of the face, throat, mouth, legs, feet or hands
• nausea, vomiting, or diarrhea
• flu-like symptoms
• fever
• bruising (with no injury)
• numbness
• difficulty moving
• painful erections (may last longer than 4 hours)

Other side effects from warfarin usage may include gangrene and subsequent amputation, or necrosis (tissue skin death).

In addition to the side effects listed above, warfarin also interacts negatively with some food products, supplements, and over-the-counter (OTC) medications. Persons taking warfarin should consult their physician before taking or consuming the following:

• Food products: cranberries and cranberry juice (increases risk of bleeding, also avoid use of cranberry supplements), garlic or black licorice, any food high in vitamin K such as spinach, broccoli, cabbage, lettuce, turnip greens, watercress, Brussels sprouts, soybeans, mayonnaise, or canola oils. Excessive use of alcohol may also lead to excessive bleeding.
• Supplements: omega-3 or fish oil (which may seem counterintuitive since it’s often recommended for heart patients), vitamin K (necessary to form blood clots so it may reduce effectiveness of warfarin), St. John’s wort, glucosamine, cranberry extracts, garlic, dong quai, ginkgo, ginseng, willow bark, primrose oil, coenzyme Q10, wintergreen, bromelain, alfalfa, and danshen.
• OTC medications: aspirin, ibuprofen, acetaminophen, birth control pills, heparin, some antibiotics, and allergy and cold medications.

Because of the increased risk of bleeding, persons taking warfarin should inform their medical care provider before undergoing any dental work, minor surgical procedures, or even routine vaccinations. It’s also a good idea to wear a medical alert bracelet so that medical professionals who may be treating you in an emergency are aware of the possibility of excessive bleeding and can respond accordingly.

For more information about warfarin usage, check out the warfarin page at The Mayo Clinic (http://www.mayoclinic.com/health/warfarin-side-effects/HB00101) or Clot Care Online Resource (http://www.clotcare.com/aboutwarfarin.aspx)

Atrial Fibrillation, The Mayo Clinic, 14 Feb 2009, http://www.mayoclinic.com/health/atrial-fibrillation/DS00291

Warfarin side effects: Watch for dangerous interactions, The Mayo Clinic, 01 15 2009, http://www.mayoclinic.com/health/warfarin-side-effects/HB00101
Henry I. Bussey, Pharm.D., FCCP, FAHA, FAQs About Warfarin (brand name for Coumadin), Clot Care Online Resource, December, 2006, http://www.clotcare.com/aboutwarfarin.aspx

Add a Comment2 Comments


Hello Mellanie,
Thank you so much for sharing the additional information along with alternative treatments. I appreciate it very much and know our readers do as well.


January 3, 2011 - 6:19pm


Good article. Here are a couple of additional resources:

1) One of my favorite resources for those on Coumadin or warfarin is at http://www.ptinr.com (here's a review I did on it a while ago: http://www.stopafib.org/newsitem.cfm/NEWSID/38 )

2) For those who don't want to deal with all the negatives and side-effects of warfarin, there is a newly-approved alternative called Pradaxa (dabigatran) - see https://www.empowher.com/atrial-fibrillation/content/pradaxa-dabigatran-approved-alternative-warfarin-reducing-atrial-fibrill

Mellanie True Hills

January 3, 2011 - 3:40pm
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We value and respect our HERWriters' experiences, but everyone is different. Many of our writers are speaking from personal experience, and what's worked for them may not work for you. Their articles are not a substitute for medical advice, although we hope you can gain knowledge from their insight.

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