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What is Warfarin (Coumadin)?


Warfarin (Coumadin) is an anticoagulant. Anticoagulants are medications that prevent and treat the formation of clots within blood vessels, also called thrombosis

Warfarin can be taken by mouth or crushed and given through a feeding tube. It comes in a tablet form. Several different strengths are available. Each tablet is marked with dose strength and color coded based on strength.

Special Instructions

  • The prothrombin time or PT and the International Normalized Ratio or INR monitor warfarin treatment. Your child will require frequent blood draws to check these levels.
  • It is very important for you to tell your child's dentist and all doctors prior to and at the beginning of each visit that he / she is taking warfarin.
  • Eating certain foods while taking warfarin will change the way the medicine works. Foods that contain vitamin K (such as lettuce, spinach, broccoli, cabbage, liver, soybean containing foods (mayonnaise, soy milk)) may make the medicine less effective in preventing blood clots. Drinking certain juices such as cranberry, grapefruit and mango can increase the risk of bleeding while taking warfarin. Carefully follow your doctor's instruction about any special diet.
  • Consistency is key while taking warfarin. Maintaining a consistent diet and taking warfarin the same way each day is important. Inform your child’s doctor of any major changes.
  • Do not give any other medicine, prescription or over the counter (OTC), without first talking to your child's doctor.
  • Do not use after the expiration date on the bottle / package.
  • Keep this medication out of the reach of children.
  • If too much medication is given by accident, call the Drug and Poison Information Center (DPIC) at 513-636-5111 or 1-800-222-1222, or call your child's doctor immediately.

If Your Child Misses a Dose

For any medicine information related to your child's dosing schedule and / or missed doses, contact the health care provider who prescribed the medicine.

Possible Side Effects of Medication

  • Bleeding
  • Bruising
  • Nausea
  • Headache
  • Light headedness

Call Your Child's Doctor If:

  • Bruises or tender swellings without obvious cause
  • Severe and prolonged headaches
  • Nose bleeds
  • Coughing up blood
  • Bleeding heavily from the gums after brushing his / her teeth
  • Prolonged bleeding from small cuts
  • Heavy bleeding at menstrual periods -- such as twice the usual flow
  • Swelling and tenderness or pain in his / her abdomen
  • Vomiting red blood or material that looks like coffee grounds
  • Bowel movements that are loose or containing blood or that are black and bad smelling
  • Urine that contains blood or that is dark brown or cloudy
  • Severe, prolonged back pain, without obvious cause
  • If your child falls or suffers a blow to the head, even if he / she does not lose consciousness or have a headache
  • Signs or symptoms of illness including fever, vomiting, or diarrhea

Last Updated 04/2022

Reviewed By Rachel Habib, PharmD