Warfarin Advice Leaflet


Is it safe to take this with WARFARIN tablets?

Advice on foods, vitamins and herbal products
Many people are prescribed WARFARIN tablets to increase the time taken for their blood to clot.

  • Too much WARFARIN may cause excessive bleeding whilst too little can lead to blood clots.
  • The dose that you take is determined by a blood test called an INR test. (lNR stands for International Normalised Ratio)
  • It is very important to have regular blood tests as many factors can alter your INR levels.

What can cause these changes?

Changes in health, drug treatment, diet and alcohol intake can affect your INR levels.

There are also certain foods, herbal medicines and vitamin supplements that may affect your INR level.

It is very important that you take care in situations where you have been injured. You must seek medical help if you have had a hard blow to your head.

lf you are already taking regular medication and/or any of the listed food/herbal/vitamin products, do not make sudden or drastic changes to your routine unless you have discussed them with your GP, Nurse or Pharmacist.



  • If any changes are made to your regular prescription e.g. the drug or the dose is changed, please make sure that the prescriber is aware that you take WARFARIN.
  • lf you are prescribed any new drugs e.g. a course of antibiotics, tell the prescriber that you take WARFARIN.

Food and Drink

The list below of common foods and drinks that may affect your INR levels is not a complete list, so always check with your GP, Nurse or Pharmacist before making dietary changes.

  • Alcohol
  • Asparagus
  • Avocado
  • Bilberry
  • Cranberry Juice I tablets
  • Fenugreek
  • Flaxseed Oil
  • Garlic
  • Ginger
  • Grapefruit Juice
  • Green Tea
  • Dark Green Leafy Vegetables e.g. Broccoli, Brussels sprouts, Cabbage, Watercress, Kale, Spinach (No more than three portions per week of dark green leafy vegetables are recommended and these should not be eaten on the same day, but spread over the week). 

Herbal medicines

The list below of common herbal remedies that may affect your INR levels is not a complete list so always check with your GP, Nurse or Pharmacist before taking any herbal remedies.

  • Alfalfa
  • Arnica
  • Aniseed
  • Chamomile
  • Chondroitin
  • Coenzyme Q10
  • Echinecea
  • Devils Claw
  • Dong quai
  • Evening Primrose Oil
  • Feverfew
  • Fish oils
  • Ginko Biloba
  • Ginseng
  • Glucosamine
  • Honse Chestnut
  • Red Clover
  • St. Johns Wort

Vitamin Supplements

Always ask your GP, Nurse or Pharmacist before taking any Vitamin Products.


Always carry your yellow book and alert card with you and make sure the book is updated with your latest INR Test Result

Make sure that you show the card and book when you:

  • Visit your GP
  • Attend a clinic or are admitted to hospital
  • Request a new prescription
  • Buy new medicines or supplements over the counter
  • Visit your dentist or other healthcare professional

If you feel unwell and are booked for a blood test, do not cancel your appointment. When you are ill it is even more important to get your INR checked.


Where can I get advice if the surgery and pharmacy are closed?