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Drugs reference index «Warfarin sodium»

Warfarin sodium

Brand names: Coumadin

Why is Warfarin sodium prescribed?

Coumadin is an anticoagulant (blood thinner). It is prescribed to:

Prevent and/or treat a blood clot that has formed within a blood vessel or in the lungs.

Prevent and/or treat blood clots associated with certain heart conditions or replacement of a heart valve.

Aid in the prevention of blood clots that may form in blood vessels anywhere in the body after a heart attack.

Reduce the risk of death, another heart attack, or stroke after a heart attack.

Most important fact about Warfarin sodium

The most serious risks associated with Coumadin treatment are hemorrhage (severe bleeding resulting in the loss of a large amount of blood) in any tissue or organ and, less frequently, the destruction of skin tissue cells (necrosis) or gangrene. The risk of hemorrhage usually depends on the dosage and length of treatment with Warfarin sodium.

Hemorrhage and necrosis have been reported to result in death or permanent disability. Severe necrosis can lead to the removal of damaged tissue or amputation of a limb. Necrosis appears to be associated with blood clots located in the area of tissue damage and usually occurs within a few days of starting Coumadin treatment.

How should you take Warfarin sodium?

The objective of treatment with a blood-thinner is to control the blood-clotting process without causing severe bleeding, so that a clot does not form and cut off the blood supply necessary for normal body function. Therefore, it is very important that you take Warfarin sodium exactly as prescribed by your doctor and that your doctor monitor your condition on a regular basis. Be especially careful to stick to the exact dosage schedule your doctor prescribes.

Effective treatment with minimal complications depends on your cooperation and communication with the doctor.

Do not take or discontinue any other medication unless directed to do so by your doctor. Avoid alcohol, salicylates such as aspirin, larger than usual amounts of foods rich in vitamin K (including liver, vegetable oil, egg yolks, and green leafy vegetables), which can counteract the effect of Coumadin, or any other drastic change in diet.

Note that Coumadin often turns urine reddish-orange.

You should carry an identification card that indicates you are taking Coumadin.

  • If you miss a dose...Take the forgotten dose as soon as you remember, then go back to your regular schedule. If you do not remember until the next day, skip the dose. Never try to "catch up" by doubling the dose. Keep a record for your doctor of any doses you miss.
  • Storage instructions...Coumadin can be stored at room temperature. Close the container tightly and protect from light.

What side effects may occur?

Side effects cannot be anticipated. If any develop or change in intensity, inform your doctor as soon as possible. Only your doctor can determine if it is safe for you to continue taking Coumadin.

  • Side effects may include:Hemorrhage: Signs of severe bleeding resulting in the loss of large amounts of blood depend upon the location and extent of bleeding. Symptoms include: chest, abdomen, joint, muscle, or other pain; difficult breathing or swallowing; dizziness; headache; low blood pressure; numbness and tingling; paralysis; shortness of breath; unexplained shock; unexplained swelling; weakness

Why should Warfarin sodium not be prescribed?

This drug should not be used for any condition where the danger of hemorrhage may be greater than the potential benefits of treatment. Unless directed to do so by your doctor, do not take Warfarin sodium if one of the following conditions or situations applies to you:

A tendency to hemorrhageAlcoholismAn abnormal blood conditionAneurysm (balloon-like swelling of a blood vessel) in the brain or heartBleeding tendencies associated with: ulceration or bleeding of the stomach, intestines, respiratory tract, or the genital or urinary systemEclampsia (a rare and serious pregnancy disorder producing life-threatening convulsions), or preeclampsia (a toxic condition—including headache, high blood pressure, and swelling of the legs and feet—that can lead to eclampsia)Excessive bleeding of brain blood vesselsInflammation, due to bacterial infection, of the membrane that lines the inside of the heartInflammation of the sac that surrounds the heart or an escape of fluid from the heart sacMalignant hypertension (extremely elevated blood pressure that damages the inner linings of blood vessels, the heart, spleen, kidneys, and brain)PregnancyRecent or contemplated surgery of the central nervous system (brain and spinal cord) or eyeSpinal puncture or any procedure that can cause uncontrollable bleedingThreatened miscarriageAllergy to any of the drug's ingredients

Special warnings about Warfarin sodium

Treatment with blood thinners may increase the risk that fatty plaque will break away from the wall of an artery and lodge at another point, causing the blockage of a blood vessel. If you notice any of the following symptoms, contact your doctor immediately:

Abdominal pain; abrupt and intense pain in the leg, foot, or toes; blood in the urine; bluish mottling of the skin of the legs and hands; foot ulcers; gangrene; high blood pressure; muscle pain; "purple toes syndrome" (see below); rash; or thigh or back pain.

If you have any of the following conditions, tell your doctor. He or she will have to consider the risks against the benefits before giving you Coumadin.

An infectious disease or intestinal disorderA history of recurrent blood clot disorders in you or your familyAn implanted catheterDental proceduresInflammation of a blood vesselModerate to severe high blood pressureModerate to severe kidney or liver dysfunctionPolycythemia vera (blood disorder)Severe diabetesSurgery or injury that leaves large raw surfacesTrauma or injury that may result in internal bleeding

Purple toes syndrome can occur when taking Coumadin, usually 3 to 10 weeks after the start of anticoagulation therapy. Symptoms include dark purplish or mottled color of the toes that turns white when pressure is applied and fades when you elevate your legs; pain and tenderness of the toes; and change in intensity of the color over a period of time. If any of these symptoms develop, notify your doctor immediately.

If you are taking Coumadin, your doctor should periodically check the time it takes for your blood to start the clotting process (prothrombin time). Numerous factors such as travel and changes in diet, environment, physical state, and medication may alter your response to treatment with an anticoagulant. Clotting time should also be monitored after your release from the hospital and whenever other medications are started, discontinued, or taken sporadically.

While taking Coumadin, avoid activities and sports that could cause an injury. Remain cautious after you stop taking Coumadin. It will continue to work for 2 to 5 days.

If you have congestive heart failure, you may become more sensitive to Coumadin and may need to have your dosage reduced. Your doctor will have you tested regularly.

Notify your doctor if any illness, such as diarrhea, infection, or fever develops; if any unusual symptoms, such as pain, swelling, or discomfort, appear; or if you see prolonged bleeding from cuts, increased menstrual flow, vaginal bleeding, nosebleeds, bleeding of gums from brushing, unusual bleeding or bruising, red or dark brown urine, red or tarry black stool, headache, dizziness, or weakness.

Possible food and drug interactions when taking Warfarin sodium

Coumadin can interact with a very wide variety of drugs, both prescription and over-the-counter. Check with your doctor before taking ANY other medication or vitamin product.

Be extremely cautious, too, about taking any herbal remedies and supplements. A wide assortment of herbal products—including St. John's wort, coenzyme Q10, bromelains, dan-shen, dong quai, garlic, cranberry products, and ginkgo biloba—are known to interact with Coumadin or otherwise affect coagulation.

Special information if you are pregnant or breastfeeding

Coumadin should not be taken by women who are or may become pregnant since the drug may cause fatal hemorrhage in the developing baby. There have also been reports of birth malformations, low birth weight, and retarded growth in children born to mothers treated with Coumadin during pregnancy. Spontaneous abortions and stillbirths are also known to occur. If you become pregnant while taking Warfarin sodium, inform your doctor immediately.

Coumadin has not been found in the breast milk of mothers taking the drug. Nevertheless, the doctor may test the baby for coagulation abnormalities before recommending that you breastfeed while on Coumadin therapy.

Recommended dosage for Warfarin sodium


The administration and dosage of Coumadin must be individualized by your doctor according to your sensitivity to the drug.

A common starting dosage of Coumadin tablets for adults is 2 to 5 milligrams per day. Individualized daily dosage adjustments are based on the results of tests that determine the amount of time it takes for the blood clotting process to begin.

A maintenance dose of 2 to 10 milligrams per day is satisfactory for most people. The duration of treatment will be determined by your physician.


Although Coumadin has been widely used in children below the age of 18, its safety and effectiveness for this purpose have not been formally established.


Low starting and maintenance doses are recommended for older people, as the drug tends to have a greater effect.


Signs and symptoms of Coumadin overdose reflect abnormal bleeding.

  • Symptoms of abnormal bleeding include:Blood in stools or urine, excessive menstrual bleeding, black stools, reddish or purplish spots on skin, excessive bruising, persistent bleeding from superficial injuries

If you suspect an overdose, seek emergency medical treatment immediately.

  • Warfarin Prescribing Information (FDA)
  • Coumadin Prescribing Information (FDA)
  • Coumadin Advanced Consumer (Micromedex) - Includes Dosage Information
  • Coumadin Consumer Overview
  • Coumadin MedFacts Consumer Leaflet (Wolters Kluwer)
  • Jantoven Prescribing Information (FDA)

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