Garlic Interactions

Clopidogrel blocks the platelet P2Y12 ADP receptor to prevent clots. Concentrated garlic supplements also have a mild antiplatelet effect through sulfur compounds such as allicin and ajoene. Taken together, the antiplatelet effects can add up and may modestly raise bleeding risk, especially before procedures. Culinary garlic in food amounts is not a meaningful concern.

Concentrated garlic supplements may add to warfarin's blood-thinning effect, mainly through a mild antiplatelet action, though the clinical evidence for important bleeding is weak.

Garlic and hawthorn each modestly lower blood pressure on their own, and both have mild blood-thinning activity, so taking them together can add up to a slightly larger drop in blood pressure and a small increase in bleeding tendency. There is no human trial of the two taken together, so any true 'synergy' beyond simple additive effects is unproven. The practical concern is layering them on top of antihypertensive, antiplatelet, or anticoagulant medication.