Abstract

Herbal and dietary supplement use is increasingly common, making awareness of herb-drug interactions an important component of patient counseling and medication safety. In stroke care, anticoagulant and antiplatelet agents such as warfarin and aspirin are widely used for prevention and treatment, yet many commonly consumed herbs and supplements may alter hemostasis and increase bleeding risk. This narrative review summarizes the literature on five commonly used herbs with potential blood-thinning properties: garlic, turmeric, cinnamon, cayenne pepper, and ginger. For each, the origin, pharmacologic effects, mechanisms of action, and reported interactions with warfarin and aspirin were examined. The reviewed literature suggests that these herbs may affect coagulation and platelet function through differing mechanisms, resulting in variable levels of clinical risk when used concurrently with standard antithrombotic therapies. Some may potentiate warfarin activity and increase bleeding complications, whereas others may act through alternative pathways with less direct influence on INR but continued relevance to hemorrhagic risk. The findings of this review support the need for clinicians to routinely inquire about herbal and supplement use in patients taking blood-thinning medications. Incorporating herbal counseling into routine stroke care may improve medication safety and reduce preventable adverse events. Additional research is needed to clarify the magnitude and clinical significance of these interactions and to better inform evidence-based counseling practices.

Keywords:Herbal supplements; Herb-drug interactions; Stroke care; Warfarin; Aspirin; Turmeric; Garlic; Ginger; Cinnamon; Cayenne pepper bleeding risk; Hemostasis; Platelet function; Anticoagulants; Antiplatelet therapy

Abbreviations: INR: International Normalized Ratio; PTT: Partial Thromboplastin Time; PT: Prothrombin Time; vWF: Von Willebrand Factor; GPIb: Glycoprotein Ib Receptor; GPIIb/IIIa: Glycoprotein IIb/IIIa Receptor; 12-HETE: 12-Hydroxyeicosatetraenoic Acid; DOACs: Direct Oral Anticoagulants; CIM: Complementary and Integrative Medicine; aPTT: Activated Partial Thromboplastin Time