Medicines to prevent blood clots: Dabigatran, rivaroxaban, apixaban.) � �
Medicines that help prevent clots are also known as "blood thinners " � and "anti-clotting medicines. " � � �
Why do I need to take warfarin? " � Doctors prescribe warfarin to people who are at risk of forming clots or who have already had them. For example, doctors prescribe warfarin to people with atrial fibrillation, a heart rhythm problem that can cause clots and lead to stroke. Doctors also prescribe it to people who have had heart valve or hip or knee replacement, because these people can develop dangerous clots. � �
If you take warfarin, there are certain things you should do, listed below. Getting your blood tested is especially important. � �
- Know the amount of warfarin you are supposed to take, what the pills look like, and why your doctor prescribed it for you " � Warfarin pills come in different strengths. Each strength is usually a different color, with the amount of warfarin (in milligrams) printed on the tablet. If the color, shape, or dose of your warfarin pills looks different from those you have taken before, check with your doctor or pharmacist.
- Take your medicine exactly as your doctor tells you to " � Take warfarin at the same time each evening and do not skip any doses. Do not change the dose or stop taking warfarin without talking to your doctor. Always refill your prescription before you run out of pills. If you forget or miss a dose, call your doctor to find out what to do.
- Use a weekly pill box " � Refill the pill box at the beginning of every week with the amount of warfarin you are told to take each day. A pill box is a big help, because sometimes you have to take a different amount depending on what day of the week it is. Also, you can check the pill box to see if you already took your pills that day. Bring the pill box with the warfarin pills inside it to your doctors appointments or pharmacist so it can be checked.
- Get your blood tested " � When you start taking warfarin, you will need to have your blood tested often to check how your blood is clotting. This is important to get the right dose for you. You will need a blood test anywhere from once a week to once a month. If you missed any warfarin doses in the last week before your blood test, tell your doctor. Based on your blood test results, your doctor will tell you if you need to change your dose and when you will need the next blood test.
- Ask your doctor before taking any new medicines " � A LOT of medicines can change the way warfarin works, so tell your doctor about ALL of the medicines you take. That includes prescription or over-the-counter medicines, herbs, and vitamins. Do not take any pain relievers without talking to your doctor. Also, make sure every doctor who prescribes anything to you knows that you take warfarin. That way the doctor can check for drug interactions before putting you on a new medicine.
- Eat about the same amount of vitamin K each day " � The amount of vitamin K you eat affects the dose of warfarin you need. Leafy greens and other vegetables are high in vitamin K and can make warfarin not work as well if the amount you eat changes from day to day. DO NOT avoid these healthy foods. Instead, eat similar amounts of vitamin K each day. That way, your vitamin K level will stay about the same, and warfarin can work as it should. This Table shows you how to do this (table 1).
- Limit alcohol " � If you drink alcohol, limit yourself to 1 to 2 servings per day. Drinking a lot of alcohol at once or drinking often while on warfarin increases your risk of bleeding. If you have more than 1 to 2 servings per day, talk to your doctor.
- If you get sick, tell your doctor " � If you get diarrhea, a fever, or an infection, or if you cannot eat, tell your doctor. These illnesses can change the way warfarin works and you might need a blood test and a change in warfarin dose. If you can't eat much because you are sick, or you go on a diet, also let your doctor know.
- Avoid risky sports and activities " � You should exercise for good health. But avoid activities that could easily lead to injury. If you get injured, you could have a serious bleed.
- Wear an alert tag " � Always wear a bracelet, necklace, or another kind of alert tag that warns people that you take warfarin and why. That way, if you are in an accident and are unable to explain your condition, people will know how to care for you. Your alert tag should also have the name and phone number of an emergency contact person.
What are the side effects of warfarin? " � The most common side effect is bleeding from any part of your body. This even includes inside your body, where you cannot see it. � �
Call your doctor RIGHT AWAY or get emergency care if you have any serious symptoms that could mean you are bleeding, such as you: � �
- Feel sick to your stomach or throw up blood or something that looks like coffee grounds
- Have headaches, dizziness, weakness, or cannot move part of your face
- Have nosebleeds or any bleeding that does not stop
- Have dark red or brown urine
- See blood in your bowel movements, or have dark-colored bowel movements
- Are in an accident or have a bad injury
- Develop unusual bruises (black and blue skin) for unknown reasons
You should also call your doctor if you: � �
- Bleed from the gums after you brush your teeth
- Swell or have pain where you got an injection
- Have heavy menstrual periods or bleeding between periods
- Have diarrhea, vomit, or are unable to eat for more than a day
- Have a fever (temperature higher than 100.4 � � � or 38 � � �)
Is there anything I can do to lower the risk of bleeding? " � Yes. You should: � �
- Use a soft bristle toothbrush
- Floss with waxed floss (not unwaxed floss)
- Shave with an electric razor rather than a razor blade
- Take care when using sharp objects, such as knives and scissors
- Avoid doing things might make you likely to fall, such as walking on slippery surfaces or climbing on a high stool
- Let all your doctors, dentists, and nurses know that you take warfarin before they give you a shot, do surgery or dental work, or start you on a new medicine
For more detailed information about your medicines, ask your doctor or nurse for information from Lexicomp available through UpToDate. The Lexicomp hand-outs explain how to use and store your medicines. They also list possible side effects and warn you if your medicines should not be taken with certain other medicines or foods. � �
All topics are updated as new evidence becomes available and our peer review process is complete. � �
This topic retrieved from UpToDate on: Nov 04, 2014. � �
Topic 16265 Version 4.0 � �
Release: 22.8 - C22.206 � �
� � 2014 UpToDate, Inc. All rights reserved. � �
� �
table 1Amount of vitamin K in different foodsView Largetable 1Amount of vitamin K in different foods
Vitamin K is found in healthy foods like leafy greens. Vitamin K helps blood to clot, so it can change the way warfarin works. This does NOT mean you need to stop eating foods with vitamin K.
Your goal is to eat about the same amount of vitamin K each day. You can do this by eating the same amount of high and medium level vitamin K foods each day using the list below.
If you are not able to eat for a few days or are making big changes in your diet, call your doctor.
Vitamin pills, herbs, or other supplements such as calcium soft chews can have vitamin K in them or can interact with warfarin. Always show your doctor the label of ALL vitamins, herbs, or other supplements that you take.
Food name
Serving size
Vitamin K (micrograms)
High vitamin K foods
Brussels sprouts, fresh (cooked, drained)
1/2 cup
110
Brussels sprouts, frozen (cooked, drained)
1/2 cup
150
Greens, beet fresh (cooked, drained)
1/2 cup
350
Greens, collard frozen (cooked, drained)
1/2 cup
530
Greens, collard fresh (cooked, drained)
1/2 cup
365
Greens, mustard fresh (cooked, drained)
1/2 cup
415
Greens, turnip fresh (cooked, drained)
1/2 cup
265
Greens, turnip frozen (cooked, drained)
1/2 cup
425
Kale, fresh (cooked, drained)
1/2 cup
530
Kale, frozen (cooked, drained)
1/2 cup
565
Spinach, fresh (cooked, drained)
1/2 cup
444
Spinach, frozen (cooked, drained)
1/2 cup
514
Spinach, fresh (raw)
1 cup
150
Medium vitamin K foods
Asparagus, frozen (cooked, drained)
1/2 cup
72
4 spears
48
Asparagus, fresh (cooked, drained)
4 spears
30
Beans, green or yellow, fresh (cooked, drained)
1/2 cup
10
Broccoli, fresh (cooked, drained)
1 spear
26
Broccoli, frozen (cooked, drained)
1/2 cup
80
Broccoli, raw
1/2 cup
45
Cabbage (cooked, drained)
1/2 cup
80
Cabbage, chinese bok-choi (cooked, drained)
1/2 cup
28
Cabbage, green (raw)
1/2 cup
26
Cabbage, red (raw)
1/2 cup
14
Cabbage, savoy (raw)
1/2 cup
24
Calcium soft chews (brand name Viactiv with D) see above about other vitamin pills
1 chew
40
Carrots, fresh or frozen (cooked, drained)
1/2 cup
10
Cauliflower, fresh or frozen (raw or cooked, drained)
1/2 cup
10
Celery, raw
1/2 cup
17
Coleslaw (fast food-type)
1/2 cup
37
Endive
1/2 cup
60
Lettuce (butterhead, Boston, bibb)
1/2 head
80
Lettuce (iceberg, crisphead)
1/2 head
65
Lettuce (romaine, cos)
1 cup
57
Lettuce (green leaf)
1 cup
97
Oil, canola
1 tablespoon
17
Okra, fresh (cooked, drained)
1/2 cup
32
Okra, frozen (cooked, drained)
1/2 cup
44
Peas, frozen, with pod (cooked, drained)
1/2 cup
24
Peas, fresh, with pod (cooked, drained)
1/2 cup
20
Peas, green, frozen (cooked, drained)
1/2 cup
18
Pickle relish, sweet
1 tablespoon
13
Pickles, cucumber dill or kosher dill
1 pickle
25
Sauerkraut, canned
1/2 cup
56
Vegetables, mixed frozen or canned (cooked, drained)
1/2 cup
20
Low vitamin K foods
Avocado
1 ounce
All of these foods have less than 10 micrograms of vitamin K per serving
Bananas
1 banana
Chickpeas (garbanzo beans)
1/2 cup
Corn
1/2 cup
Fruit (fresh, frozen or canned including apples, nectarines, peaches, watermelon)
Whole piece of fresh fruit, 1 wedge of watermelon, or 1/2 cup
Mayonaise
1 tablespoon
Oil, olive
1 tablespoon
Oil, other (including peanut, sesame, safflower, corn, sunflower, soybean)
1 tablespoon
Peppers, green or red
1/2 pepper or 1/2 cup
Potatoes
1 potato or 1/2 cup
Seaweed, kelp (raw)
1 tablespoon
Tomatoes
1 tomato or 1/2 cup
Very low vitamin K foods, but MIGHT change how warfarin or other medicines work
Cranberry juice
4 ounces juice
If you eat these foods, limit the amount to one or two servings per day
Grapefruit
4 ounces juice
1/2 grapefruit
Green tea, brewed
4 ounces
Graphic 65279 Version 2.0
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