If you take warfarin (Coumadin, Jantoven) or other blood thinners, you should be aware of possible side effects and always wear a medical ID bracelet.

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Warfarin (Coumadin) Side Effects to Watch Out For


(March 2014) Taking daily doses of blood thinning medications like warfarin is a fact of life for more than two million Americans. These medicines, often distributed under the brand names Coumadin, Jantoven, Marevan, Uniwarfin or Warf, are commonly prescribed for people at high risk for heart attacks, strokes and other dangerous blood clotting issues. While they certainly save lives, these medications also have the potential to cause severe side effects.

The most common side effects of warfarin are bruising and bleeding. To prevent blood clots within the body, the medication blocks the formation of vitamin K-dependent clotting factors. While this prevents harmful clots from forming within the body’s arteries and veins, it can also prevent blood from clotting at sites of injury or trauma. This is where excessive bruising and/or bleeding can occur, even with a simple cut.

Additional warfarin side effects can result from interactions with certain foods and other prescription or over-the-counter medicines and supplements.

Other serious side effects seen with warfarin include:

  • Black stool or rectal bleeding
  • Hives, rash or itching
  • Swelling of the face, throat, mouth, legs, feet or hands
  • Chest pain or pressure
  • Nausea or vomiting
  • Fever or flu-like symptoms
  • Joint or muscle aches
  • Diarrhea
  • Difficulty moving
  • Numbness or tingling in any part of your body
  • Painful erection lasting four hours or longer

If you experience any of the symptoms above, contact your doctor immediately. Likewise, if you notice any sores, changes in skin color or temperature, or feel severe pain on your skin. These could be signs of a rare reaction that could result in necrosis, dying flesh.

To reduce the risks of warfarin side effects, tell your doctor about any and all medications or supplements you take, prescription or over-the-counter. You may also want to take a warfarin sensitivity test. Some people are genetically predisposed to heavier bleeding and this test will help your doctor make an informed decision about dosage. When it comes to prescription medications, awareness is key, so make sure healthcare providers know you’re on warfarin before scheduling any procedures.

Medical ID bracelets are recommended for anyone who takes warfarin. Medical ID bracelets (or other forms of medical ID jewelry) provide important health information to first responders in the event of an emergency. When you’re not capable of letting others know about your warfarin medication, or other critical medical data, the ID bracelet does it for you.

For more information on warfarin (Coumadin), read this helpful article from the American Heart Association.