LifeBridge Health > Anticoagulation Clinics > Frequently Asked Questions about Anticoagulants

Frequently Asked Questions about Anticoagulants

What is Coumadin®?
How does this medication work?
How much do I take?
When do I take it?
Why are regular blood tests so important?
When will I have to get a PT/INR test?
What can change my PT/INR test results?
Do I have to pay attention to the vitamin K in my diet?
Are there any restrictions on my exercise or activities?
Are there any symptoms that could be related to my condition or warfarin that I should know about?


What is Coumadin®?

Coumadin® is an anticoagulant medicine. It is also known by the generic name warfarin. It is used to prevent unwanted blood clots from forming in your body. Blood clots can cause a stroke or heart attack or can form in the legs or lungs.


How does this medication work?

Warfarin interferes with the body's ability to form clots by blocking the formation of vitamin K-dependent clotting factors in the liver. Although anticoagulants such as warfarin are called blood thinners, warfarin does not actually make your blood thinner.


How much do I take?

Your health care provider determines the amount of warfarin you need by giving you a blood test called a prothrombin time, or PT, test. The prothrombin time is then converted to a standard unit called an international normalized ratio (INR). After each test your dosage may change, so it is important to always follow the instructions from your most recent visit.


When do I take it?

Take your medication at the same time every day. Take it exactly the way your health care provider tells you. If you forget to take a pill, tell your health care provider. Take the missed dose as soon as possible on the same day. Do not take a double dose of medication the next day to make up for the missed dose.


Why are regular blood tests so important?

To benefit from warfarin and lower your chance for bleeding problems, you must get regular blood tests to check your response to warfarin. The PT/INR test checks to see how quickly your blood clots. Your dose of warfarin will be adjusted to keep your PT/INR in the right target range for you. This level may change depending on your health, if you have an illness or if you eat foods rich in vitamin K.


When will I have to get a PT/INR test?

Your health care provider will determine how often you need blood tests. This depends on how stable the blood test results have been, whether your dose of warfarin has been changed recently and whether other factors that may alter your dose of warfarin have happened recently.


What can change my PT/INR test results?

Sickness, diet, other medications (prescription and over-the-counter) or physical activities may affect your PT/INR. Tell your health care provider about changes in your health, medications or lifestyle.


Do I have to pay attention to the vitamin K in my diet?

It is important to maintain a consistent diet with respect to foods high in vitamin K. Vitamin K reverses the effect of warfarin. If you constantly change the amounts you eat, it can greatly affect your warfarin therapy. Vitamin K-rich foods include most green leafy vegetables such as spinach, kale, broccoli, lettuce, cauliflower, cabbage, Brussels sprouts and collard greens, as well as other foods. Do not make any major changes to your diet without first speaking with your health care provider.


Are there any restrictions on my exercise or activities?

While you are taking warfarin, it is important to avoid contact sports and activities that put you at high risk for injuries and bleeding.


What other information should I tell my health care provider?

Before starting warfarin, tell your health care provider about all your health conditions.

You may need to stop taking warfarin before surgery, diagnostic procedures or dental work. It is important that you inform your physician and dentist that you are taking warfarin. Also, please inform the Anticoagulation Clinic of upcoming procedures that may require interruption of warfarin therapy.

It is important not to become pregnant while on warfarin. Please take proper precautions to prevent becoming pregnant. Contact your physician immediately if you believe you may be pregnant.


Are there any symptoms that could be related to my condition or warfarin that I should know about?

Call 911 or your physician immediately if you experience any of the following signs or symptoms:

  • Headaches, dizziness or weakness
  • Red or dark brown urine
  • Red or black, tarlike stools
  • Vomiting or coughing up blood
  • Increased menstrual flow or vaginal bleeding
  • Uncontrolled bleeding or unusual bruising
  • Chest pain
  • One-sided numbness or tingling, blurred or lost vision, slurred speech
  • Fainting, loss of consciousness, any serious fall (especially if you hit your head)
  • Difficulty catching your breath