Licorice and Warfarin

Publication Date: 
Fri, 09/06/2013
By: Alere Staff


Next time you have a sweet tooth and you are craving candy, take a minute to think about how some sweets may affect your INR. Warfarin is used to slow blood clotting and licorice may influence the effectiveness of warfarin. This in turn could increase the chance of a blood clot forming or lead to an increased risk of bleeding. Since the average person does not eat large quantities of licorice, there is a relatively low risk this candy would have an effect on your INR.

There is a component however, in licorice root (cytochrome p450) that does influence the way your body clears warfarin. The potential is there for a slight increase influence of warfarin clearance.1

Like anything else you eat, when you are on warfarin, you need to have a consistent diet. So, first check with your doctor to see how they feel about you eating licorice. If they give you the “ok”, just make sure you eat the same amount of the same kind of licorice every day (black licorice may have a different effect than red).

Be sure to check your INR regularly as prescribed by your doctor as your warfarin dosage may need to be changed. Increasing testing frequency is recommended when starting or stopping any new medication, dietary supplements, or trying new foods. Home INR monitoring will help improve your control of warfarin.

Increasing testing frequency is recommended when making any changes to your diet, medication, etc. Studies have shown that increasing testing frequency with weekly testing of INR improves patient safety and helps keep the drug in its therapeutic effective zone.2,3 Weekly testing was shown to be the most effective testing frequency.2 Medicare and many private/commercial insurance reimburse patients for weekly patient self-testing.4 Go to the Getting Started page or call Alere at 1.800.504.4032 for more information about testing your INR at home.

  1. Drug Metabolism and Disposition. American Society for Pharmacology and Experimental Therapeutics. 2002. 30(6): 709-715.
  2. Am J Manag Care. 2014;20(3):202-209.
  3. Heneghan C., et al. Self-monitoring of oral anticoagulation: a systematic review and meta-analysis. 2006. Lancet, 367, 404-11.
  4. Center for Medicare and Medicaid Services. Decision Memo for Prothrombin Time (INR) Monitor for Home Anticoagulation Management  (CAG-00087R) [Memorandum]. 2008. Baltimore, MD.