Drugs A - Z

Warfarin Sodium Oral tablet

It is used to treat or prevent clots in the veins, arteries, lungs, or heart

Generic Name: warfarin  |  Brand Name: Coumadin

Brand Names: Warfarin Sodium, Coumadin, Jantoven

There is an FDA Alert for this drug. Click here to view it.

Special Alerts:

[Posted 08/16/2007] FDA approved updated labeling to include pharmacogenomics information to the CLINICAL PHARMACOLOGY, PRECAUTIONS, and DOSAGE AND ADMINISTRATION sections of the prescribing information for the widely used blood-thinning drug, warfarin (Coumadin). This new information explains that people’s genetic makeup may influence how they respond to the drug. Specifically, people with variations in two genes may need lower warfarin doses than people without these genetic variations. The two genes are called CYP2C9 and VKORC1. The CYP2C9 gene is involved in the breakdown (metabolism) of warfarin and the VKORC1 gene helps regulate the ability of warfarin to prevent blood from clotting.

The dosage and administration of warfarin must be individualized for each patient according to the particular patient’s prothrombin time (PT) / International Normalized Ratio (INR) response to the drug. The specific dose recommendations are described in the warfarin product labeling, along with the new information regarding the impact of genetic information upon the initial dose and the response to warfarin. Ongoing warfarin therapy should be guided by continued INR monitoring. For more information visit the FDA website at: [Web].

[Posted 10/06/2006] FDA and Bristol-Myers Squibb notified pharmacists and physicians of revisions to the labeling for warfarin (Coumadin), to include a new patient Medication Guide as well as a reorganization and highlighting of the current safety information to better inform providers and patients.

The FDA regulation 21CFR 208 requires a Medication Guide to be provided with each prescription that is dispensed for products that FDA determines pose a serious and significant public health concern. Information about all currently approved Medication Guides is available at: [Web]. For more information visit the FDA website at: [Web], and [Web].

What is this medicine?

WARFARIN (WAR far in) is an anticoagulant. It is used to treat or prevent clots in the veins, arteries, lungs, or heart.

What should I tell my health care provider before I take this medicine?

They need to know if you have any of these conditions:
  • alcoholism
  • anemia
  • bleeding disorders
  • cancer
  • diabetes
  • heart disease
  • high blood pressure
  • history of bleeding in the gastrointestinal tract
  • history of stroke or other brain injury or disease
  • kidney or liver disease
  • protein C deficiency
  • protein S deficiency
  • psychosis or dementia
  • recent injury, recent or planned surgery or procedure
  • an unusual or allergic reaction to warfarin, other medicines, foods, dyes, or preservatives
  • pregnant or trying to get pregnant
  • breast-feeding

How should I use this medicine?

Take this medicine by mouth with a glass of water. Follow the directions on the prescription label. You can take this medicine with or without food. Take your medicine at the same time each day. Do not take it more often than directed. Do not stop taking except on the advice of your doctor or health care professional.

A special MedGuide will be given to you by the pharmacist with each prescription and refill. Be sure to read this information carefully each time.

Talk to your pediatrician regarding the use of this medicine in children. Special care may be needed.

What if I miss a dose?

It is important not to miss a dose. If you miss a dose, call your healthcare provider. Take the dose as soon as possible on the same day. If it is almost time for your next dose, take only that dose. Do not take double or extra doses to make up for a missed dose.

What may interact with this medicine?

Do not take this medicine with any of the following medications:
  • agents that prevent or dissolve blood clots
  • aspirin or other salicylates
  • danshen
  • dextrothyroxine
  • mifepristone
  • St. John's Wort
  • red yeast rice

This medicine may also interact with the following medications:

  • acetaminophen
  • agents that lower cholesterol
  • alcohol
  • allopurinol
  • amiodarone
  • antibiotics or medicines for treating bacterial, fungal or viral infections
  • azathioprine
  • barbiturate medicines for inducing sleep or treating seizures
  • certain medicines for diabetes
  • certain medicines for heart rhythm problems
  • certain medicines for high blood pressure
  • chloral hydrate
  • cisapride
  • disulfiram
  • female hormones, including contraceptive or birth control pills
  • general anesthetics
  • herbal or dietary products like cranberry, garlic, ginkgo, ginseng, green tea, or kava kava
  • influenza virus vaccine
  • male hormones
  • medicines for mental depression or psychosis
  • medicines for some types of cancer
  • medicines for stomach problems
  • methylphenidate
  • NSAIDs, medicines for pain and inflammation, like ibuprofen or naproxen
  • propoxyphene
  • quinidine, quinine
  • raloxifene
  • seizure or epilepsy medicine like carbamazepine, phenytoin, and valproic acid
  • steroids like cortisone and prednisone
  • tamoxifen
  • thyroid medicine
  • tramadol
  • vitamin c, vitamin e, and vitamin K
  • zafirlukast
  • zileuton


Last Updated: November 15, 2012
Licensed from
The Healthline Site, its content, such as text, graphics, images, search results, HealthMaps, Trust Marks, and other material contained on the Healthline Site ("Content"), its services, and any information or material posted on the Healthline Site by third parties are provided for informational purposes only. None of the foregoing is a substitute for professional medical advice, examination, diagnosis, or treatment. Always seek the advice of a physician or other qualified healthcare provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on the Healthline Site. If you think you may have a medical emergency, call your doctor or 911 immediately. Please read the Terms of Service for more information regarding use of the Healthline Site.
Advertisement
Advertisement