Treatments and tests

Your lifestyle choices with warfarin

Along with other medications, some of your lifestyle choices may affect your International Normalised Ratio (INR), which in turn may affect your warfarin dose.


Some foods interact with warfarin and affect your treatment and dose.

It is important to:

  • maintain a regular balanced diet
  • reduce alcohol intake to a maximum of 1 to 2 standard drinks per day.

Do certain foods affect warfarin?

Some foods can interact with and affect warfarin.

Foods high in vitamin K are the most important to be aware of because the body uses vitamin K to help clotting. Vitamin K is not the same as potassium which is also called K or K+ in food and vitamins.

What foods are high in vitamin K?

Food high in vitamin K includes dark green leafy vegetables, for example spinach, broccoli, cabbage, brussel sprouts and some offal such as liver.

Do I need to avoid vitamin K?

Don’t avoid foods high in vitamin K as you need it for a healthy diet.

You should:

  • have a healthy balanced diet including lots of different types of food
  • eat about the same amount of dark leafy green vegetables and other food high in vitamin K weekly
  • consult your doctor before you change your diet.

What happens if I change my diet?

You may need extra blood tests if you make any big changes to your diet. Contact your doctor if your diet has changed.


Avoid heavy or binge drinking while taking warfarin as drinking alcohol can affect the way warfarin works.

Drinking small amounts of alcohol (1 to 2 standard drinks per day) is unlikely to cause problems.

Standard drinks

Learn more about what is considered a standard drink in Australia.

One standard drink is equal to:

  • 1 small glass of wine
  • 1 nip of spirits
  • 1 middy of normal strength beer.

Where to get help


  • Some foods interact with warfarin and affect your treatment and dose.
  • You will need to watch your intake of foods containing vitamin K.
  • Alcohol can also affect how much warfarin you need to take, so consider how much you drink.


Western Australian Therapeutic Advisory Group | The WA Medication Safety Group

This publication is provided for education and information purposes only. It is not a substitute for professional medical care. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your healthcare professional. Readers should note that over time currency and completeness of the information may change. All users should seek advice from a qualified healthcare professional for a diagnosis and answers to their medical questions.

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