Coumadin Side Effects Center

What Is Coumadin?

Coumadin (warfarin) is a blood anticoagulant that inhibits the function of Vitamin K dependent coagulation used to inhibit the coagulation of blood to reduce or prevent the chance of developing heart attacks (myocardial infarctions), strokes, and venous and other blood clots (deep venous thromboses, pulmonary emboli and thrombi produced with atrial fibrillation). Coumadin is also used to treat these conditions if they develop. Coumadin is available as a generic.

What Are Side Effects of Coumadin?

Common side effects of Coumadin include

• easy bruising and bleeding,
• nausea,
• vomiting,
• stomach pain,
• bloating,
• gas, or
• altered sense of taste.

Dosage for Coumadin

Coumadin has a wide range of tablets: 2, 2.5, 3, 4, 5, 6, 7.5 and 10 mg tablets are available. An injectable form of the drug (5 mg) is also available. The dose of Coumadin is determined in each individual by administering a trial dose and ten measuring the patient's INR (International Normalized Ratio), a lab test that is standardized by the WHO (world Health Organization) and recognized worldwide. Therapeutic ranges for this test are between 2.0 to 3.0 when a patient is taking Coumadin. INR levels below 2 may allow easier blood clotting to occur while levels above 3 may cause excessive tendency for the patient to bleed.

What Drugs, Substances, or Supplements Interact with Coumadin?

Coumadin may interact with other medications to prevent blood clots, antibiotics, antifungals, sulfa drugs, medicines to treat tuberculosis, antidepressants, herbal (botanical) products (including coenzyme Q10, cranberry, echinacea, garlic, ginkgo biloba, ginseng, goldenseal, or St. John's wort), secobarbital, barbiturates, seizure medications, and other drugs. Tell your doctor all medications and supplements you use.

Coumadin During Pregnancy and Breastfeeding

Pregnant women should not be given Coumadin; lactating women may need to be closely monitored and their breastfed infants should have their INR checked, according to some investigators. Although Coumadin has been used in pediatric patients to prevent clot formations, children under 18 have not been well studied with this drug and some investigators suggest achieving stable INR levels seems more difficult in the pediatric population.

Additional Information

Our Coumadin Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Warfarin increases your risk of bleeding, which can be severe or life-threatening. Call your doctor at once if you have any signs of bleeding such as:

• sudden headache, feeling very weak or dizzy;
• swelling, pain, unusual bruising;
• bleeding gums, nosebleeds;
• bleeding from wounds or needle injections that will not stop;
• heavy menstrual periods or abnormal vaginal bleeding;
• blood in your urine, bloody or tarry stools; or
• coughing up blood or vomit that looks like coffee grounds.

Clots formed by warfarin may block normal blood flow, which could lead to tissue death or amputation of the affected body part. Get medical help at once if you have:

• pain, swelling, hot or cold feeling, skin changes, or discoloration anywhere on your body; or
• sudden and severe leg or foot pain, foot ulcer, purple toes or fingers.

Bleeding is the most common side effect of warfarin.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.