Coumadin (Warfarin Sodium) is prescribed for the prophylaxis and/or treatment of venous thrombosis and its extension, and pulmonary embolism. It is also indicated for the prophylaxis and/or treatment of the thromboembolic complications associated with atrial fibrillation and/or cardiac valve replacement, reducing the risk of death, recurrent myocardial infarction, and thromboembolic events such as stroke or systemic embolization after myocardial infarction.

The dosage and administration of Coumadin must be individualized for each patient according to the particular patient's PT/INR response to the drug and his / her condition. The starting dose is usually 2 to 5 milligrams (mg) per day for two to four days which may later be adjusted depending on the condition and blood test results.

While taking Coumadin, it is very important to avoid sports and activities that may cause injury. Any falls, blows to the body or head or other injuries should be reported to the doctor immediately since serious internal bleeding may occur without the patient becoming aware of it. Patients should also be careful to avoid cutting themselves. This includes special care to be taken in brushing teeth and shaving. It is better to use a soft brush and floss gently as well as to use an electric shave and avoid a blade. Drinking too much alcohol may change the way this anticoagulant affects the body. It is advisable to avoid drinking on a daily basis and also take no more than one or two drinks at any time.

Like all other medicines, Coumadin also has its side effects which include hypersensitivity/allergic reactions, systemic cholesterol microembolization, purple toes syndrome, hepatitis, cholestatic hepatic injury, jaundice, elevated liver enzymes, vasculitis, edema, fever, rash, dermatitis including bulbous eruptions, urticaria, abdominal pain including cramping, flatulence/bloating, fatigue, lethargy, malaise, asthenia, nausea, vomiting, diarrhea, pain, headache, dizziness, taste perversion, pruritus, alopecia, cold intolerance, and paresthesia including feeling cold and chills. Any bleeding while the PT/INR is within therapeutic range should be diagnostically investigated since it could mean a previously unsuspected lesion like a tumor or ulcer. The anticoagulant effect of the medication may also cause fatal or nonfatal hemorrhage from any tissue or organ. The possibility of hemorrhage should be always considered in evaluating the condition of any anticoagulated patient with complaints which do not indicate an obvious diagnosis.

Bleeding during anticoagulant therapy does not always correlate with PT/INR. After the medicine is stopped, the body needs time to recover before it can return to its normal blood clotting ability. It is necessary that the same care be taken during this period as during the treatment in order to ensure that no unexpected complications occur.