Question: Does CoQ10 interact with blood thinners? Answer: There are studies with conflicting results on whether CoQ10 may interfere with warfarin treatment or decrease the effectiveness of warfarin (Coumadin). There are studies that suggest that CoQ10 may increase the risk of bleeding when on warfarin and other studies that suggest CoQ10 may decrease the risk of bleeding when on warfarin. Other studies indicate that there is no effect so long as your INR (bleeding time) is stable. It’s not clear whether CoQ10 affects Plavix treatment. Consult with your doctor before taking any supplement or medication.

Source: ConsumerLab Q&A