antiplatelet
14 interactions related to antiplatelet
warfarin + dong quai
Dong quai (Angelica sinensis) contains coumarin derivatives (ferulic acid, osthole) and has documented antiplatelet activity. A widely cited case report (Page & Lawrence, Pharmacotherapy 1999, PMID 10417036) described a woman whose INR rose to 4.9 within four weeks of adding dong quai 565 mg once to twice daily to stable warfarin.
warfarin + feverfew
Feverfew (Tanacetum parthenium) inhibits platelet aggregation in vitro via its parthenolide sesquiterpene lactones. There are no robust human case reports of bleeding with warfarin specifically, but standard herbal-interaction references (StatPearls, Australian Prescriber) recommend avoidance based on the pharmacologic plausibility of additive bleeding risk.
aspirin + ginkgo
Ginkgo biloba can inhibit platelet-activating factor (PAF) and platelet aggregation, which can add to aspirin's irreversible inhibition of cyclooxygenase-1 and thromboxane A2. The combination may modestly increase minor bleeding events, with case reports of more serious bleeds in vulnerable patients.
aspirin + fish oil
Omega-3 fatty acids in fish oil reduce platelet aggregation and prolong bleeding time slightly, theoretically adding to aspirin's antiplatelet effect. Clinical trials, however, consistently show no clinically significant increase in major bleeding even with high-dose fish oil added to aspirin.
warfarin + ginger
Ginger inhibits thromboxane synthase and reduces platelet aggregation; case reports describe elevated INR after addition of oral ginger to stable warfarin therapy. A 2019 case report (Rubin et al., Case Reports in Medicine) and the Tan 2021 BJCP systematic review document the signal, though controlled trials in healthy volunteers have been mixed.
warfarin + ginkgo
Ginkgo biloba inhibits platelet-activating factor and can prolong bleeding time, adding an antiplatelet effect on top of warfarin's vitamin-K-antagonist anticoagulation. A 2025 PLOS One analysis of 2,647 prescriptions found ginkgo co-prescription was associated with a significantly higher rate of bleeding adverse events (hazard ratio ~1.38) and abnormal coagulation profiles.
warfarin + turmeric
Curcumin, the main active in turmeric, has antiplatelet activity and may also inhibit CYP2C9 metabolism of warfarin, raising warfarin levels. New Zealand Medsafe issued an alert in 2018 after a patient's INR rose above 10 within weeks of starting a turmeric/curcumin product on previously stable warfarin therapy.
clopidogrel + ginkgo
Ginkgo biloba inhibits platelet-activating factor and may add to clopidogrel's blockade of the platelet P2Y12 ADP receptor. While a healthy-volunteer study did not detect additive platelet inhibition, observational and case-report data link the combination to increased bleeding, including intracranial hemorrhage.
turmeric tea + warfarin
Curcumin, the principal active compound in turmeric, has antiplatelet and anticoagulant activity in vitro (inhibiting thrombin and factor Xa) and inhibits CYP enzymes involved in warfarin metabolism. Case reports describe INR rising above 10 within weeks of starting turmeric in patients on stable warfarin.
clopidogrel + garlic
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.
alcohol + aspirin
Alcohol and aspirin together significantly increase the risk of gastrointestinal bleeding because aspirin irreversibly inhibits platelets for their entire 7-10 day lifespan while alcohol damages the gastric lining and impairs clot formation. The risk is particularly elevated for daily low-dose aspirin users who drink regularly.
acai + warfarin
Acai berries contain polyphenols, salicylate-like compounds, and unsaturated fatty acids that may have mild antiplatelet activity, but there are no published case reports of clinically significant INR changes. The theoretical concern is additive bleeding risk at high doses or with concentrated extracts, not enzymatic CYP interference.
vitamin e + platelet function test
High-dose vitamin E (alpha-tocopherol above 400 IU per day) inhibits platelet aggregation through a protein kinase C-dependent mechanism, producing prolonged bleeding times and abnormal results on platelet function analyzers (such as PFA-100, VerifyNow, and light transmission aggregometry). The effect is most pronounced when vitamin E is combined with aspirin or other antiplatelet agents and can interfere with workup for bleeding disorders.
warfarin + garlic
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.