Garlic Interactions

Concentrated garlic supplements have antiplatelet activity (mainly via ajoene and allicin) and have been associated with elevated INR and bleeding when added to warfarin in case reports and herbal-interaction reviews. The Vaes & Chyka review in Annals of Pharmacotherapy classified garlic as a potential potentiator of warfarin via additive antithrombotic effect.

Garlic supplements, especially aged garlic extract, inhibit platelet aggregation through reduced thromboxane B2 and altered platelet membrane function. Combined with clopidogrel's P2Y12 blockade, this adds antiplatelet effect and can increase bleeding risk, particularly with concentrated supplement doses.

Aged garlic extract lowers blood pressure through endothelial nitric oxide release, mild ACE inhibition, and antioxidant effects, while hawthorn flavonoids provide vasodilation, mild positive inotropy, and improved coronary flow. Together they act on complementary aspects of vascular tone and cardiac function in mild hypertension.