Warfarin (Coumadin, Jantoven)
Web Based Resources:
UW Health - Anticoagulation Services
Clot Care Online Resource
National Blood Clot Alliance
Patient Dosing Sheet for Warfarin
Warfarin Indication _____________________________ Goal INR __________
Start date __________ Stop Date ___________ Tablet Strength _________ mg
Fill in INR from each lab draw date. Add dose in mg for each day of the week. Make any changes to sheet as needed. Example provided
|1/1||2.0||5 mg||3 mg||5 mg||3 mg||5 mg||3 mg||5 mg|
Tell your warfarin manager of
- Change in diet
- Change in medicines
- Missed or extra doses
- Unusual bruising or bleeding
- Upcoming procedures or trips
What is warfarin?
Warfarin sodium (Coumadin®, Jantoven®) is a drug that is often referred to as a “blood thinner.” It works to prevent the production of clotting factors. This causes the blood to take longer to form a clot and can also prevent a clot from getting bigger.
Why do I need a blood thinner?
It may be used to prevent a clot from forming or it can be used to treat an existing clot. Some risk factors for developing blood clots are listed below.
- Atrial Fibrillation
- Heart Failure
- Heart Valve Replacement
- Treatment or prevention of DVT (deep vein thrombosis)
- Treatment or prevention of PE (pulmonary embolism)
What dose should I take?
There is no standard dose. The amount needed varies for each person. The dose is changed based on a blood test called the INR. It is a test to measure how long it takes for your blood to clot.
How can I tell what dose I am taking?
Both generic (warfarin) and brand (Coumadin®, Jantoven®) will use the same color theme, but tablets may be different shapes and sizes.
What is my target INR range?
Your target INR range depends on why you are taking warfarin. Most people on blood thinners will have a target INR range of 2-3 or 2.5-3.5. Your doctor will tell you your INR range.
How often will my INR be checked?
You will need to be tested 2-3 times per week when you first start. Once your INR and dose become more constant you may be able to test less often, about once per month. Your warfarin manager will tell you how often to have your blood tested.
When should I take my warfarin?
Warfarin should be taken once a day. Take your dose exactly as prescribed and at the same time every day. Most people are told to take their dose in the evening.
What happens if I miss a dose?
If you miss a dose and remember within 12 hours, you may take your dose. If it has been more than 12 hours do not take your missed dose. Take your scheduled dose for the current day and call your clinic. Be sure to report the missed dose to your warfarin manager.
Never double up on your dose to make up for a missed dose. Never change your dose unless your warfarin manager has told you to do so.
What does a warfarin manager do?
The person who manages your warfarin will determine your warfarin dose. To find the dose that is right for you, they will ask you questions about your other medications and lifestyle choices that can change your INR. Based on your answers to these questions and the INR level, they will tell you what warfarin dose to take and when to have the INR checked again.
Keep reading to see how medications, lifestyle and diet can change your INR.
Bleeding is the most common side effect. Minor bleeding can occur even if your INR is within your target range.
- Bleeding gums during tooth brushing
- Bruising more than usual
- Occasional nose bleeds
- Prolonged menstrual bleeding (heavier than normal)
- Prolonged bleeding after minor cuts
You may notice these side effects at times. If you have any question about whether your bleeding is a concern call your warfarin manager.
- Any bleeding that lasts for more than 10 minutes
- Coughing up blood
- Vomiting blood
- Frequent nose bleeds, bleeding gums, or unusual bleeding
- Unexplained bruising
- Red or dark brown urine
- Red, black, or tarry stool
- Severe headache
- Severe stomachache
If you have a serious fall, hit your head or if you are having any of these major bleeding side effects call your doctor or go to the Emergency Department right away.
Interactions with other medicines
Prescription drugs, over-the-counter (OTC) products, herbal products and supplements can affect how your blood thinner works. Any time you start or stop a new medicine, herb, or vitamin you must tell your warfarin manager.
Listed below are some of the medicines that can increase your INR, decrease your INR or put you at an increased risk for bleeding. These are not complete lists.
Medicines and other products that can increase your INR:
- Amiodarone (Pacerone®)
- Alcohol (acute ingestion)
- Ciprofloxacin (Cipro®)
- Fluconazole (Diflucan®)
- Metronidazole (Flagyl®)
- Moxifloxacin (Avelox®)
- TMP/Sulfa (Bactrim®)
- Voriconazole (Vfend®)
If you start any antibiotic you should call your warfarin manager
Medicines and other products that can decrease your INR:
- Carbamazepine (Tegretol®)
- Cholestyramine (Questran®)
- Co-Enzyme Q10
- Dicloxacillin (Dynapen®)
- Green Tea
- Nafcillin (Nafcil®)
- Nutritional Drinks (some)
- Phenytoin (Dilantin®)
- Rifampin (Rifadin®)
- St. John’s Wort
- Tube feeds
Medicines and other products that can increase your risk of BLEEDING:
- Celecoxib (Celebrex®)
- Clopidogrel (Plavix®)
- Fish Oil (omega-3 fatty acid)
- Ibuprofen (Motrin®)
- Indomethacin (Indocin®)
- Naproxen (Aleve®)
- Prasugrel (Effient®)
- Prednisone (Deltasone®)
- Vitamin E
To help prevent interactions, you must let your doctors and pharmacists know you are taking warfarin. Also try to fill all your drugs at the same pharmacy. Your pharmacist can help screen for interactions.
What lifestyle changes could affect my INR?
A change in activity level can affect your INR. Tell your warfarin manager if you either increase or decrease your activity level. You should also avoid activities that may place you at risk for injury, such as contact sports. Do not play contact sports without talking to your doctor first. You may engage in low risk physical activities, such as walking, jogging, or swimming.
If you are planning to travel tell your warfarin manager before your trip. You may need to make plans for INR checks. You should also carry your medicines with you at all times. Luggage may get lost and drugs left in cars may degrade in extreme heat or cold.
Acute illness can change your response to warfarin. Tell your doctor or clinic if you have any of the symptoms listed below.
- Nausea or vomiting
- Severe flu-like symptoms
- Started on an antibiotic
Limit alcohol to no more than 1 drink per day, or no more than 1 to 2 drinks on a special occasion. Drinking more can greatly increase your risk for bleeding. You should tell your warfarin manager about any amount of alcohol you consume.
Surgical, Dental, or other Medical procedures
Tell all members of your health care team (surgeons, dentist, etc.) that you are taking a blood thinner. You may need to stop taking it before certain procedures. Be sure to tell your warfarin manager if you were told to stop or hold your warfarin. They may need to change you to another type of blood thinner before your procedure. See page 13 for more information.
If you are placed on a type of blood thinner that you inject, often called “bridging,” keep taking this until your warfarin manager tells you to stop.
If you think you are or may become pregnant, tell your doctor right away. Taking blood thinners while you are pregnant may cause harm to your unborn baby. You should use a form of birth control. If you become pregnant your doctor will instruct you about other treatment options.
Medical Alert Information
In case of an emergency or accident you will want to wear a medical alert bracelet or necklace or carry an identification card. This will alert the health care team that you are taking a blood thinner. Ask your local pharmacy or doctor how you can obtain these.
How Diet Affects Warfarin
Some foods and other items you take can change the way your warfarin works including:
- Foods that contain Vitamin K (see table)
- Some nutritional drinks or tube feedings
Vitamin K is common to many foods, such as green leafy vegetables. They can reduce the effects of warfarin when eaten in large amounts. You can still eat Vitamin K type foods but you should eat the same amount of these foods from week to week. Be aware of how many times per week and how many servings you eat of food high in vitamin K.
|Foods high in Vitamin K (serving size ½ cup cooked or 1 cup raw)
If these foods are a part of your diet, continue eating the same amounts
|Green Tea Endive lettuce|
|Swiss Chard Romaine lettuce|
|Brussels sprouts Green leaf lettuce|
|Parsley (okay as a garnish) Soy Beans/Edamame|
|Turnip and Mustard Greens|
Other vegetables, fruits, cereals, dairy products, eggs, and meat contain smaller amounts.
• Eat the same amounts of Vitamin K foods from week to week.
• Note: usual serving size ½ cup cooked or 1 cup raw
Nutritional Drinks, Meal Replacement Shakes, and Weight Loss Shakes:
Meal replacement, weight loss, nutritional drinks or shakes may have high amounts of vitamin K per serving. If you will be starting one of these products tell your warfarin manager. The following drinks have vitamin K. This is not a complete list.
- Carnation Breakfast Essentials®
- Slim Fast®
If you plan on changing your diet either short or long term let your warfarin manager know. They may need to watch your INR more closely.
Signs and Symptoms of Blood Clots or Stroke
Warfarin is commonly used to prevent or treat blood clots or to prevent the occurrence of a stroke. Below are common signs and symptoms of each.
Deep Vein Thrombosis (DVT) – blood clot commonly in the leg
- Pain or tenderness in limb
- Swelling or redness in limb
- Skin warm to touch
Pulmonary Embolism (PE) – blood clot in the lung
- Chest pain
- Feeling short of breath
- Cough (with or without blood)
- Fast breathing
- Fast heart rate
- Low grade fever or mild sweating
If you are having any of these above signs or symptoms of a blood clot this could be a medical emergency and you should report to the nearest emergency department immediately.
Stroke – sudden onset of the following:
- Headache (described as the worst headache you ever had)
- Changes in vision
- Feeling weak on one side of the body
- Slurred speech or difficulty speaking words
- Feeling confused
If you are having any of these above signs or symptoms of stroke this is a medical emergency and you should call 911 immediately.
Take Home Points
- Take your warfarin exactly as prescribed.
- Never double up on a dose if missed.
- Tell all of your health care team that you are taking a blood thinner.
- Know the signs and symptoms of bleeding and report them right away.
- Know the signs and symptoms of a blood clot and stroke and seek medical attention immediately.
- Tell your warfarin manager if there are any changes in your medicines, diet, or activity level.
- Tell your warfarin manager if you were told to hold or stop warfarin before a procedure.
- Keep all scheduled visits or call promptly to reschedule.
Vitamin K Content in Food
M = Medium H = High
For more information www.ptinr.com – vitamin K registry
Stopping Warfarin Therapy for Procedures or Surgery
You are on a blood thinning medicine called warfarin. There may be a time when you need to stop taking this drug if you will be having work done which might lead to bleeding. This may include: a dental visit, biopsy, minor or major surgery.
Ask the doctor or dentist if you will need to stop this blood thinner and for how long it should be stopped. If they want you to stop taking your warfarin, please tell them to contact the clinic that manages your warfarin. You should also call the clinic that manages your warfarin to tell them you will need to stop it for a short time.
Before stopping warfarin for a procedure or surgery your doctor will consider the following factors:
• Reason for warfarin
• Your individual risk for clotting or stroke
• The clotting and bleeding risk of the procedure
• How long you will need to off of the warfarin
Please know there are some procedures where warfarin may be continued since bleeding risk is considered low:
• Simple dental procedures – including extractions
• Cataract surgery
• Diagnostic or screening colonoscopies
• Minor skin surgeries
If you need to stop warfarin your doctor may start you on an alternative anticoagulant that you inject into the skin. Follow the directions closely on when to give this new medication and when stop and restart your warfarin. There may be some time when you are taking both the warfarin and injection until your INR returns into goal range.
Select the best answer for each question.
1. What is the name of the blood test used to monitor warfarin levels?
b. Platelet count
c. Red blood cell count
2. How often do you need a blood test?
a. Once a year
b. At regular intervals, decided on by my doctor or clinic
c. Only after a dose changes
3. If your INR is high, you may be at risk for:
b. Serious bleeding
c. Heart attack
4. What should you do if you miss a dose of warfarin?
a. Take my dose as soon as I remember on the same day. If it is the next day, I will just resume my normal dosing and tell my healthcare provider.
b. Nothing- it is okay to skip one dose
c. Take an extra pill to "catch up"
5. What should you do if you want to take an over-the-counter medicine or
a. I can't take any over-the-counter medicines or vitamins while on warfarin
b. Go ahead and start the new medicines, your provider does not need to know.
c. Call my provider and ask if the new item will be safe with warfarin.
6. What should you do if you really enjoy eating spinach or other green, leafy
a. Stop eating them altogether
b. Only eat them if INR is high
c. Be constant with the amount that I eat
d. Just eat 1 big bowl per month
7. Who should you tell that you take warfarin?
a. All my doctors
b. My dentist
c. My pharmacist
d. All of the above
1. Ageno W, Gallus AS, Wittkowsky A, et al. Oral Anticoagulant Therapy: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed. American College of Chest Physicians Evidence Based Clinical Practice Guidelines. CHEST. 2012;141:e44s-88s.
2. Holbrook A, Schulman S, Witt D, et al. Evidence Based Management of Anticoagulant Therapy: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed. American College of Chest Physicians Evidence Based Clinical Practice Guidelines. CHEST. 2012;141:e152s-184s.
3. Holbrook AM, et al. Systematic overview of warfarin and its drug and food interactions. Arch Intern Med. 2005; 165:1095-1106.
4. Wittkowsky AK. Drug interactions update: drug, herbs and oral anticoagulation. J Thromb Thrombolysis. 2001; 12:67-71.
5. Warfarin [package insert]. Princeton, NJ: Bristol-Meyers Squibb Pharma Company; revised Jan 2009.
Warfarin Emergency Pocket Card
Keep this card in your wallet or purse in case of emergencies. It allows emergency personnel to know that you are on warfarin.
The information provided should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Any duplication or distribution of the information contained herein is strictly prohibited.
Last Updated: 06/12/2013
Copyright © 06/12/2013 University of Wisconsin Hospitals and Clinics Authority. All rights reserved. Produced by the Department of Nursing. HF#6900
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