Parsley and Warfarin

Publication Date: 
Tue, 11/08/2011
By: Alere Staff

The golden rule in leafy green vegetables is they will normally decrease the effect of warfarin or lower a your INR test result when consumed over time. Parsley is the anomaly.

While parsley has the same enzymes that make warfarin thin the blood, it also has a high concentration of vitamin K which helps the body make clots. According to the USDA, 10 sprigs of raw parsley has 164 micrograms and 1 tablespoon (tbsp) of dried parsley has 17.7 micrograms of vitamin K.1 Individuals may react differently to parsley with respect to a possible influence on their INR. The best strategy would be to evaluate parsley during stable INR tests and have your blood checked 3-5 days following consumption of parsley (greater than ¼ cup over several days).

Evaluating the effects of parsley should be done in cooperation with your healthcare provider team. INR results higher than a your target range increases the risk of bleeding while lower INR test results increase the risk of clotting which could lead to a potential stroke.


  1. U.S. Department of Agriculture, Agricultural Research Service. 2004. USDA National Nutrient Database for Standard Reference, Release 17. Nutrient Data Laboratory Home Page,