Vitamin C and Anticoagulation: No Direct Blood-Thinning Effect

Vitamin C (ascorbic acid) does not possess anticoagulant or antiplatelet properties. It does not alter INR, aPTT, platelet function, or the pharmacokinetics of warfarin, DOACs (apixaban, rivaroxaban, dabigatran, edoxaban), heparin, or antiplatelet agents (aspirin, clopidogrel).

Evidence

• Clinical trials and pharmacokinetic studies show no clinically significant interaction between vitamin C (even high-dose IV) and anticoagulants.
• Vitamin C is a water-soluble antioxidant; its metabolic pathways (renal excretion, oxidation to dehydroascorbate) do not intersect with coagulation cascades.

Caveats

• High-dose IV vitamin C may interfere with point-of-care glucose meters (falsely elevated readings) and some lab assays—irrelevant to coagulation.
• Vitamin E, omega-3 fatty acids, garlic, ginkgo, ginseng do have mild antiplatelet effects and can potentiate bleeding with anticoagulants.

Patients on anticoagulants can safely consume dietary vitamin C or standard supplements (75–90 mg/day RDA; UL 2000 mg/day). Always inform clinicians of all supplements.