Possible Interactions with Vitamin K

Overview

Vitamin K counteracts the effects of the blood-thinning medication warfarin, rendering the medication ineffective. When taking this medication, do not take vitamin K supplements and avoid foods with high quantities of this nutrient.

Antibiotics, particularly a class known as cephalosporins, reduce the absorption of vitamin K. This is a particular problem for people who already have low levels of vitamin K or are at risk for deficiency (such as those who are malnourished, elderly, or taking warfarin).

The cholesterol-lowering medication cholestyramine may also reduce the absorption of vitamin K.

Taking anticonvulsants (such as phenytoin) during pregnancy or while breastfeeding may deplete vitamin K in newborns; consult your obstetrician and/or pediatrician for advice on nutrient replacement therapy.

Drug Interactions

• Anticonvulsants
• Cephalosporins
• Warfarin