Warfarin (Coumadin) is an anticoagulant (blood thinner) that has been on the U.S. market for over six decades since its initial approval by the U.S. Food and Drug Administration (FDA) in 1954.
Warfarin prevents blood clots. The drug is also used to prevent strokes in patients with atrial fibrillation (AF or AFib) (a condition resulting in an irregular heart rate).
An estimated 2.6 million individuals suffer from AF in the U.S. That’s predicted to jump to 12 million by 2050.
This drug has a black box warning for bleeding. Users must regularly test their International Normalized Ratio (INR), a blood-clotting measurement.
The tests help determine dosage. Any changes to diet, the starting or stopping of other drugs, or certain lifestyle choices, such as alcohol intake or cigarette smoking, can all alter a patient’s INR.
What Does Warfarin Treat?
Warfarin fights blood clots. It prevents clots from forming in blood and blood vessels. The drug treats certain types of irregular heartbeats. It is also used in patients who have suffered a heart attack or have prosthetic heart valves.
Coumadin is used to prevent and treat venous thrombosis (a blood clot in a vein), as well as a related condition, pulmonary embolism. A pulmonary embolism happens when part of a blood clot breaks away and becomes lodged in an artery supplying blood to the lungs.
Warfarin is also used to prevent and treat strokes associated with atrial fibrillation (AF or AFib). AF is the most common heart-rhythm abnormality, according to the FDA.
The condition is characterized by an irregular and often rapid heart rate that can increase a patient’s risk of suffering from stroke among other serious and sometimes deadly conditions, such as heart failure and other heart-related complications.
Coumadin may also be prescribed to reduce the risk of death from heart attacks and thromboembolic events, such as stroke or system embolization (a blocked artery often caused by a blood clot) after a heart attack.
Warfarin’s Black Box Warning: Bleeding Risk
Coumadin contains a black box warning for bleeding risks. Since the drug is designed to prevent blood from clotting, it can also take longer than usual for patients to stop bleeding if they are cut or injured.
Bleeding linked to Coumadin-use can also result in increased menstrual flow or vaginal bleeding in women, nosebleeds and bleeding of the gums from teeth brushing.
The drug label advises patients to report any unusual bleeding, bruising or other signs and symptoms of internal bleeding, such as headache, dizziness or weakness to their health care provider.
Additionally, health care providers are urged by the warning label to perform regular monitoring of INR and PT levels for patients treated with Coumadin.
Warfarin Side Effects?
Aside from bleeding, Coumadin-use is associated with several other side effects. These side effects can range from mild adverse reactions, such as nausea or abdominal pain, to serious complications, such as calciphylaxis (calcium build-up in small blood vessels of the fat and skin tissues) and tissue necrosis (death of body tissue).
Serious side effects of Warfarin
- Calciphylaxis (a serious, potentially deadly, condition characterized by calcification of blood vessels) – this condition can lead to blood clots and skin necrosis
- Tissue necrosis or gangrene (death of skin or body tissues)
- Hemorrhage (severe bleeding)
- Acute kidney injury
- Cholesterol embolism (blockage of an artery, typically by a clot) – this condition occurs when cholesterol is released, usually from plaque build-up in the arteries, and travels through the bloodstream becoming lodged in blood vessels in various parts of the body
- Restriction of blood supply to limbs tissue death and gangrene in patients with heparin-induced thrombocytopenia (low blood platelet count) (HIT) and HITTS (heparin-induced thrombotic thrombocytopenia syndrome)
Common side effects
The most common side effects reported in patients taking Coumadin include:
- Hypersensitivity or allergic reaction – can result in hives as well as anaphylaxis. When anaphylaxis occurs, the condition can become deadly and requires immediate emergency medical attention
- Inflammation of the skin (dermatitis), including bullous eruptions (fluid-filled blisters)
- Elevated liver enzymes
- Nausea and/or vomiting
- Changes in the sense of taste
- Abdominal pain
- Hepatitis (inflammation of the liver) – cholestatic hepatitis has been found to occur in patients taking both Coumadin and ticlopidine (a drug that also helps to prevent blood clots), simultaneously
- Vasculitis (an extreme reaction to a drug) – leads to inflammation and damage to blood vessels, primarily in the skin
- Gas and/or bloating
- Itchy skin
- Hair loss
- Feeling cold or chills