 Coenzyme Q10 has potential to inhibit the effects of theophylline as well as the anticoagulant warfarin; coenzyme Q10 may interfere with warfarin's actions by interacting with cytochrome p450 enzymes thereby reducing the INR, a measure of blood clotting.The structure of coenzyme Q10 is very similar to that of vitamin K, which competes with and counteracts warfarin's anticoagulation effects.Coenzyme Q10 should be avoided in patients currently taking warfarin due to the increased risk of clotting.