Supplements Affecting Blood Clotting
Introduction to High-Risk Supplements
- The American College of Cardiology recommends that garlic, ginkgo biloba, ginger, turmeric, vitamin E, and fish oil/omega-3 fatty acids be considered for discontinuation before surgical procedures due to their antiplatelet effects 1
Supplements with Documented Antiplatelet Effects
- Garlic inhibits platelet function through multiple mechanisms, particularly at doses of 12g daily, and has been documented to cause spontaneous bleeding events when combined with SSRIs, with a clinically significant antiplatelet effect 1
- Ginkgo biloba affects platelet function and should be held for 2 weeks before surgery due to increased bleeding risk 1
- Ginger inhibits platelet aggregation in vitro and has been associated with case reports of elevated INR and epistaxis, requiring caution in patients at bleeding risk, through inhibition of thromboxane synthesis 1
- Turmeric/Curcumin inhibits platelet aggregation via thromboxane metabolism and calcium channel inhibition, also inhibiting generation of thrombin and factor Xa, with anti-inflammatory and antiplatelet effects 1
- Vitamin E has antiplatelet effects related to inhibition of protein kinase C, which are worsened when taken with aspirin, with higher serum levels associated with bleeding in non-valvular atrial fibrillation patients on warfarin 1
Additional Supplements with Coagulation Effects
- St. John's wort may decrease platelet aggregation and can cause serotonin syndrome when combined with other serotonergic agents, and strongly induces CYP3A4, affecting warfarin metabolism 1
- Saw palmetto may increase bleeding time leading to increased risk of hematuria and operative bleeding through cyclooxygenase inhibition 1
- Vanadium (sodium orthovanadate) prolongs clotting time via inhibitory effects on both factor Xa and thrombin 1
Perioperative Management
- The American Heart Association recommends that all supplements with antiplatelet effects should ideally be discontinued 1-2 weeks before elective surgery to minimize bleeding risk 1
- Patients taking supplements with antiplatelet effects should be carefully monitored for bleeding complications, particularly in the perioperative setting or when combined with antiplatelet medications 1
Over-the-Counter Supplements and Platelet Function
Supplements with Antiplatelet Effects
- The American Society of Anesthesiology recommends that supplements with antiplatelet effects, such as Ginkgo biloba, should be held for 2 weeks before surgery due to their effect on platelet function, which can increase the risk of bleeding in patients undergoing surgery 2, 3.
- Ginger has been shown to inhibit platelet aggregation in vitro, with case reports of elevated INR and epistaxis, and should be used with caution in patients at risk of bleeding 2, 3.
- Garlic has been documented to inhibit platelet function, particularly at doses of 12g daily when combined with SSRIs, and may increase the risk of spontaneous bleeding events 2.
- Flaxseed oil has been associated with decreased platelet aggregation in healthy men and may increase the risk of bleeding 2, 4.
- Green tea extract, containing EGCG, inhibits platelet aggregation and decreases binding of fibrinogen to platelet surface GPIIb/IIIa, but may be continued until surgery despite bleeding risk, according to the 2021 Mayo Clinic guidelines 2, 3.
- Fenugreek aqueous extracts inhibit the coagulation process in vitro and significantly prolong prothrombin time, indicating a potential risk of bleeding 2, 4.
- Turmeric/Curcumin has anti-inflammatory and antiplatelet effects, with prolongation of activated partial thromboplastin time, and may increase the risk of bleeding 3, 4.
- Fish oil/Omega-3 fatty acids inhibit platelet-to-platelet adhesion and platelet-stimulated thrombin generation in vitro, but a large placebo-controlled trial showed no increase in perioperative bleeding, and the 2021 Mayo Clinic guidelines recommend continuation 3, 4.
Perioperative Management
- The American Society of Anesthesiology and multiple surgical societies recommend that all supplements with antiplatelet effects should ideally be discontinued 1-2 weeks before elective surgery to minimize the risk of bleeding 2, 3, 4.
- A survey found that 19% of surgical patients were taking supplements with potential coagulation effects, and 12.5% of these patients had actual intraoperative hemorrhage, highlighting the importance of supplement history in preoperative evaluation 2, 4.