Version July 2025
Please read the Disclaimer at the end of this page.
What is warfarin? —
Warfarin (brand name: Jantoven) is a medicine used to prevent or treat blood clots. It is also known as Coumadin, an old brand name.
The advice below also applies to other medicines that work like warfarin. Examples include acenocoumarol and phenprocoumon.
What is vitamin K? —
This helps the body make proteins that are important for blood clotting and bone health. Most vitamin K comes from foods, especially plant foods like green, leafy vegetables.
Why do I need to watch how much vitamin K I eat? —
If you take warfarin, you need to eat about the same amount of vitamin K each day. That's because the amount of vitamin K in your diet affects the amount of warfarin you need. Do not take vitamin K supplements unless your doctor tells you to.
A dietitian (food expert) can help you manage the amount of vitamin K in your diet.
What can I eat and drink while taking warfarin? —
It is OK to eat foods with vitamin K in them. Many of these foods are a part of a healthy diet. It is important to get about the same amount of vitamin K from foods every day.
To keep a steady amount of vitamin K in your diet:
●Know how much vitamin K you are taking in each day. Try to eat the same number of servings each day, and each week, from the list of foods that are "high" and "medium" in vitamin K. Portion sizes can affect how much vitamin K you are getting.
●Be aware if you are eating more foods from the "high-vitamin K" group than you normally do.
●Vitamin K can also be found in some nutrition supplement drinks, natural products, multivitamins, and calcium supplements. If you use any of these, check the labels of each product so you know how much vitamin K is in them. If you are not sure, ask your doctor, nurse, pharmacist, or dietitian. It's OK to take the same multivitamin every day.
●If you make a big change in the amount of vitamin K foods you eat, or if you cannot eat for 2 or more days, tell your doctor, nurse, or pharmacist. They might want to do a blood test to find out if you need to change your warfarin dose.
What foods have vitamin K? —
The table has examples of foods that are high, medium, and low in vitamin K (table 1).
What else should I know? —
Many medicines and herbal supplements, as well as alcohol, can change how warfarin works in unpredictable ways.
●Tell your doctor, nurse, and pharmacist about all your medicines. This includes prescription and over-the-counter medicines, natural products, and vitamins.
●It's also important to tell them about any health conditions you have. They can make sure it is safe for you to take warfarin.
●Do not start, stop, or change the dose of any medicine or supplement without checking with your doctor.
●How much alcohol you drink in a day can affect your warfarin dose. If you choose to drink, limit alcohol to no more than 2 drinks a day (for males) or 1 drink a day (for females). Do not binge drink (have many drinks at once).
Your doctor, nurse, pharmacist, or dietitian will tell you if you should follow other specific guidelines.
Patient education: How to take anticoagulants safely (The Basics)
Patient education: Anticoagulant medicines – Uses and kinds (The Basics)
Patient education: Diet and health (The Basics)
Patient education: Warfarin (Beyond the Basics)
Patient education: Diet and health (Beyond the Basics)
