Read this important information before taking:
Warfarin
Brought to you by the Institute for Safe Medication Practices
[ Extra care is needed because warfarin is a high-alert medicine. ]
High-alert medicines have been proven to be safe and effective. But these medicines can cause serious injury if a mistake happens
while taking them. This means that it is very important for you to know about this medicine and take it exactly as directed.
When taking warfarin (blood thinner)
1 Take exactly as directed. Take your medicine at the same time each day. Do not take
extra doses or skip any doses.
Top 10 List of Safety Tips for Warfarin
When the doctor changes your dose
2 Keep a record of telephone calls. When your doctor, nurse, or pharmacist calls to
change your dose: write down the dose and any other instructions; read the dose and in-
structions back to him or her to make sure you understand them; and date the instructions
so they won’t be mixed up with older instructions.
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3 Know your dose. Always tell your doctor the strength of warfarin tablets that you have on
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hand. Then ask him or her how much warfarin to take, and how many tablets in that strength
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to take to equal the dose. If you are running low on tablets, ask for a new prescription.
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4 Keep instructions nearby. Keep the dated instructions near the medicine, and read
them every time before taking your warfarin.
5 Restart your medicine. If your doctor told you to stop taking warfarin until your next blood
test, call him or her if you don’t hear anything within 24 hours of the test to find out your new
dose or when to restart your prior dose.
To avoid serious side effects
6 Keep to your regular habits. Keep your eating habits and exercise regular. Know the
foods high in vitamin K to avoid or eat consistently (see other side of this page). Tell your doc-
tor if there has been a recent change in your level of exercise, diet, or how often you smoke.
7 Take precautions. Because serious bleeding can occur, take precautions. Use an elec-
tric razor, avoid sharp objects, and keep away from fall risks (climbing ladders, for example).
8Get regular blood tests. Keep all appointments for regular blood tests (called INR).
Call your doctor for your test results if you are not contacted within 24 hours of the test.
When you should call your doctor
9 Signs of bleeding or clot. Call your doctor immediately if you experience any signs of
bleeding or clot formation, which are listed on the other side of this page.
10 New medicines. Do not start or stop any prescription or nonprescription medicines,
Call herbals, or vitamins without telling your doctor. Common nonprescription medicines to
avoid can be found on the other side of this page in the Fast Facts table.
ISMP © 2021
Warfarin tablets may come in different shapes. But each
strength comes in just one color. Make sure the color of
1 mg 2 mg 2.5 mg 3 mg 4 mg 5 mg 6 mg 7.5 mg 10 mg
your tablets matches the strength your doctor prescribed. Pink Purple Green Tan Blue Peach Teal Yellow White
For more information to help keep you safe, visit: www.consumermedsafety.org.
Report these signs to your doctor right away!
Warfarin
Too little, too much!
Too little warfarin can cause a blood clot, too much can lead to bleeding
Some foods high in vitamin K
Signs of bleeding Unusually heavy/long menstrual flow
Unusual pain, swelling, discomfort Coughing up blood Do not eat
(may also be a sign of a clot) Vomit that is bloody or looks like coffee Cranberries/cranberry juice
Unusual or easy bruising grounds
Pink or brown urine Feeling very dizzy, weak, faint, tired Eat the same amouont of foods th
Prolonged bleeding of gums or cuts Bad headache have high vitamin K day to day
Repeated nosebleeds that don’t Bloody or black poop Beef or pork liver
stop within 7 minutes Pain in joints or back Green tea
Parsley, basil, thyme
Signs of a clot Chickpeas
In the lung: chest pain, fast heart rate, coughing, shortness of breath, fever Green leafy vegetables, such as
In the arm or leg: sudden leg, arm, or back pain, swelling, redness, warmth, soreness spinach, kale, turnip greens,
In the brain: headache, vision changes, seizure, slurred speech, weakness on one Swiss chard, cabbage
side of body, dizziness Broccoli and Brussels sprouts
In the heart: chest pain, shortness of breath, sweating, nausea and vomiting Many cooking oils
In the abdomen: abdominal pain, vomiting, diarrhea For more information: www.ismp.org/ext/650
Topics Fast Facts
Generic name warfarin (pronounced WAR far in) (generic available)
Common brand names Coumadin and Jantoven
Common uses Prevent and treat blood clots in certain conditions that increase the risk of clots, such as: surgery,
heart attack, heart rhythm problem, heart valve replacement, immobility after an accident
Prevent transient ischemic attacks (mini strokes, short episodes of low oxygen to the brain)
Normal dose Up to 10 mg daily for adult patients. Your dose may be based on a lab test that
shows how sensitive you are to the medicine
Doses are changed from time to time based on INR blood test results
What to do if you miss a dose If it is still the same day, take the dose as soon as you remember it
If it is the next day, skip the missed dose and take your normal dose
Do not take two doses to catch up
Call your doctor if you miss two or more doses in a row
Special instructions and precautions Take exactly as prescribed. Take at the same time each day
Do not drink alcohol. Keep eating habits and exercise regular
You may start bleeding easily. Use a soft toothbrush, waxed dental floss, electric razor. Do
not use sharp objects. Be careful with fall risks, like climbing a ladder
Do not start or stop any medicine without talking to your doctor or pharmacist. These
include medicines with no prescription, herbals, and vitamins
Safety during pregnancy/breastfeeding Do not take when pregnant. It may cause fetal bleeding or abnormalities
May take while breastfeeding. Let the infant’s doctor know for proper monitoring
Tell your doctor if you have: Diseases: bleeding disorders, kidney disease, liver disease, thyroid disease, severe
high blood pressure, diabetes
Conditions: surgery, history of falls or if you are at risk for falls, open wound
Storage and how to throw away Keep at room temperature, protect from light and moisture (do not keep in bathroom)
Throw away tablets securely in the trash; do not flush down the toilet
Side effects to report to your doctor Signs of bleeding or clot (see top of page), skin irritation, painful red-purple patches on skin
right away (toe, breast, abdomen), unusual fever, unhealed wounds, yellow eyes or skin
Other conditions to report to your doctor Accidents or falls (even if you feel fine), new or stopped medicines (including antibiotics,
medicines with no prescription, herbals, vitamins), changes in smoking/eating habits, infection
Nonprescription Aspirin (unless prescribed by your doctor), nonsteroidal anti-inflammatory drugs (ibuprofen
medicines/herbals/vitamins that should [Advil, Motrin], naproxen [Aleve]), most herbals (particularly cranberry, fenu-greek, garlic, ginkgo
not be taken with warfarin biloba, glucosamine, American ginseng, ginger, goldenseal, coen-zyme Q10, St. John’s wort,
alfalfa, anise, bilberry), cimetidine (Tagamet), vitamins A or E
Prescription medicines you should not Check with your doctor, as many prescription medicines interact with warfarin
take with warfarin Tell your doctor and pharmacist about all the medicines you take
Special tests your doctor may prescribe You must have blood tests (called INR) checked regularly
Your doctor will decide the right INR level (usually between 2 and 3.5) for you
This information does not replace the need to follow your doctor’s instructions. Read the medicine drug information leaflet provided with your prescription.
This project was supported by grant number R18HS017910 from the Agency for Healthcare Research and Quality.
