Health Library


Warfarin (Coumadin)


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

Warfarin is taken orally. 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

  • Warfarin treatment is monitored by the prothrombin time or PT and the International Normalized Ratio or INR. Your child's physician may want to have blood drawn periodically to check these levels.
  • It is very important for you to tell your child's dentist and / or all doctors prior to and at the beginning of each visit that he / she is taking warfarin.
  • Eating certain foods while you are using warfarin will change the way the medicine works. Foods that contain vitamin K (such as lettuce, spinach, broccoli, cabbage, liver or soybean-containing food such as mayonnaise, soy milk) may make the medicine less effective in preventing blood clots. Drinking certain juices such as cranberry, grapefruit and mango can make the medicine too effective and increase risk of bleeding. Carefully follow your doctor's instruction about any special diet.
  • 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 513-636-511,1 or 1-800-222-1222, or call your child's doctor immediately.

If Your Child Misses a Dose

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

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

Last Updated 11/2019