Drug & supplement interaction

Ginkgo + Warfarin

Warfarin brand name: Warfarin.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Warfarin falls into 6 drug categories that Ginkgo can interact with; the most serious is rated moderate. Theoretically, ginkgo might decrease levels of drugs metabolized by CYP2C19.

Read the full interaction report
SeverityModerate
LikelihoodProbable
Interactions6
EvidenceB
What do Severity, Likelihood & Evidence mean?
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Interaction report

Ginkgo and Warfarin

These two interact in 6 distinct ways. Each one is explained separately below.

Why Are There 6 Interactions?

Ginkgo interacts with whole categories of medication. Warfarin falls into 6 of those categories, so it can interact with Ginkgo in 6 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES

1 of 6

Why this applies to Warfarin

Warfarin falls under CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES — the group Ginkgo interacts with.

Theoretically, ginkgo might decrease levels of drugs metabolized by CYP2C19.
Some clinical research shows that a specific ginkgo leaf extract (Remembrance, Herbs Product LTD) 140 mg twice daily can induce CYP2C19 enzymes and potentially decrease levels of drugs metabolized by these enzymes. However, other clinical research shows that taking ginkgo 120 mg twice daily for 12 days has no effect on levels of drugs metabolized by CYP2C19.
Severity Moderate Likelihood Probable Evidence B

Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the thing to know about pairing ginkgo with warfarin: warfarin is a narrow-therapeutic-index drug, meaning the right dose for you sits in a tight window. Small shifts can push you toward bleeding or toward clotting. The lab-based concern is that ginkgo might speed up a liver enzyme (CYP2C19) that helps clear warfarin, which could theoretically lower its blood-thinning effect over time.

Honestly, the evidence here is mixed and weak. One ginkgo product nudged that enzyme, while another study showed no effect. The bigger, better-documented worry is that ginkgo itself can thin the blood, so combining it with warfarin may raise your bleeding risk (think easy bruising, nosebleeds, or blood in urine or stool). Please don't start or stop anything on your own. Check with your pharmacist or doctor first, and keep up with your INR testing.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Yin OQ, Tomlinson B, Waye MM, et al. Pharmacogenetics and herb-drug interactions: experience with Ginkgo biloba and omeprazole. Pharmacogenetics 2004;14:841-50. PubMed
  2. Lei, H. P., Wang, G., Wang, L. S., Ou-yang, D. S., Chen, H., Li, Q., Zhang, W., Tan, Z. R., Fan, L., He, Y. J., and Zhou, H. H. Lack of effect of Ginkgo biloba on voriconazole pharmacokinetics in Chinese volunteers identified as CYP2C19 poor and extensiv
Moderate

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES

2 of 6

Warfarin also falls under CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES.

Theoretically, ginkgo might increase levels of drugs metabolized by CYP1A2.
Laboratory research suggests that ginkgo leaf extract can mildly inhibit CYP1A2 enzymes. However, clinical research suggests ginkgo might not affect CYP1A2. Until more is known, use ginkgo cautiously in patients taking drugs metabolized by these enzymes.
Severity Moderate Likelihood Possible Evidence B

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the deal with warfarin and ginkgo. The interaction on file is about ginkgo possibly slowing down a liver enzyme called CYP1A2 that helps break warfarin down. In theory, if that enzyme is blocked, warfarin could build up and thin your blood more than intended. But honestly, the evidence here is weak and a bit mixed. Lab studies hint at it, while human studies suggest ginkgo may not really touch CYP1A2 much at all.

My bigger concern is separate: ginkgo itself can thin the blood. Stacked on warfarin (a narrow-margin drug), that could raise your bleeding risk, think easy bruising, nosebleeds, or bleeding gums. Please don't start or stop anything on your own. Check with your pharmacist or doctor first, and keep up with your INR checks.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Gurley BJ, Gardner SF, Hubbard MA. Clinical assessment of potential cytochrome P450-mediated herb-drug interactions. AAPS Ann Mtg & Expo Indianapolis, IN: 2000; Oct 29 - Nov 2:presentation #3460.
  2. Galluzzi S, Zanetti O, Binetti G, et al. Coma in a patient with Alzheimer's disease taking low dose trazodone and Ginkgo biloba. J Neurol Neurosurg Psychiatry 2000;68:679-80. DOI
  3. Budzinski JW, Foster BC, Vandenhoek S, Arnason JT. An in vitro evaluation of human cytochrome P450 3A4 inhibition by selected commercial herbal extracts and tinctures. Phytomedicine 2000;7:273-82. PubMed
  4. Gurley BJ, Gardner SF, Hubbard MA, et al. Cytochrome P450 phenotypic ratios for predicting herb-drug interactions in humans. Clin Pharmacol Ther 2002;72:276-87.. PubMed
Moderate

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES

3 of 6

Warfarin also falls under CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES.

Theoretically, ginkgo might increase levels of drugs metabolized by CYP2C9.
In vitro, a specific standardized extract of ginkgo leaf (EGb 761) inhibits CYP2C9 activity . The terpenoid (ginkgolides) and flavonoid (quercetin, kaempferol, etc.) constituents seem to be responsible for this effect. Most ginkgo extracts contain some amount of these constituents. Therefore, other ginkgo leaf extracts might also inhibit the CYP2C9 enzyme. However, clinical research suggests that ginkgo might not have a significant effect on CYP2C9 in humans. Ginkgo does not seem to significantly affect the pharmacokinetics of CYP2C9 substrates diclofenac or tolbutamide.
Severity Moderate Likelihood Possible Evidence D

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the situation with warfarin and ginkgo. Warfarin is a blood thinner that your liver clears using an enzyme called CYP2C9. In a test tube, ginkgo appears to slow that enzyme down, which in theory could let warfarin build up a bit and make your blood thinner than intended. That could show up as easier bruising, nosebleeds, bleeding gums, or blood in the urine or stool.

Honestly though, this lab finding hasn't held up well in actual human studies, so the real risk is uncertain. The bigger concern is that ginkgo itself can mildly thin the blood. Since warfarin is a drug where small swings matter a lot, please don't add ginkgo without checking with your doctor or pharmacist first, and keep up with your regular INR checks.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Yale SH, Glurich I. Analysis of the inhibitory potential of Ginkgo biloba, Echinacea purpurea, and Serenoa repens on the metabolic activity of cytochrome P450 3A4, 2D6, and 2C9. J Altern Complement Med 2005;11:433-9.
  2. Gaudineau C, Beckerman R, Welbourn S, Auclair K. Inhibition of human P450 enzymes by multiple constituents of the Ginkgo biloba extract. Biochem Biophys Res Comm 2004;318:1072–8. PubMed
  3. Mohutsky MA, Anderson GD, Miller JW, Elmer GW. Ginkgo biloba: evaluation of CYP2C9 drug interactions in vitro and in vivo. Am J Ther 2006;13:24-31. PubMed
Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

4 of 6

Warfarin also falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES.

Theoretically, ginkgo might decrease levels of drugs metabolized by CYP3A4.
There is conflicting evidence about whether ginkgo induces or inhibits CYP3A4. Ginkgo does not appear to affect hepatic CYP3A4. However, it is not known if ginkgo affects intestinal CYP3A4. Preliminary clinical research suggests that taking ginkgo does not significantly affect levels of donepezil, lopinavir, or ritonavir, which are all CYP3A4 substrates. Other clinical research also suggests ginkgo does not significantly affect CYP3A4 activity. However, there are two case reports of decreased efavirenz concentrations and increased viral load in patients taking ginkgo. It is suspected that terpenoids from the ginkgo extract reduced drug levels by inducing cytochrome P450 3A4 (CYP3A4).
Severity Moderate Likelihood Possible Evidence B

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the honest picture with warfarin and ginkgo. The enzyme angle (CYP3A4) is mostly theoretical and the data are conflicting, so I wouldn't lose sleep over it on its own. The bigger, more practical concern is that ginkgo can thin the blood on its own. Stack that on top of warfarin, which already lowers your blood's ability to clot, and you may tip toward easier bleeding.

Warfarin is a narrow therapeutic index drug, meaning small shifts matter a lot. Watch for unusual bruising, nosebleeds, bleeding gums, pink or red urine, or dark stools. Please don't start or stop anything yourself. Loop in your pharmacist or doctor first, and they may check your INR more closely if you add ginkgo.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Gurley BJ, Gardner SF, Hubbard MA. Clinical assessment of potential cytochrome P450-mediated herb-drug interactions. AAPS Ann Mtg & Expo Indianapolis, IN: 2000; Oct 29 - Nov 2:presentation #3460.
  2. Galluzzi S, Zanetti O, Binetti G, et al. Coma in a patient with Alzheimer's disease taking low dose trazodone and Ginkgo biloba. J Neurol Neurosurg Psychiatry 2000;68:679-80. DOI
  3. Budzinski JW, Foster BC, Vandenhoek S, Arnason JT. An in vitro evaluation of human cytochrome P450 3A4 inhibition by selected commercial herbal extracts and tinctures. Phytomedicine 2000;7:273-82. PubMed
  4. Gurley BJ, Gardner SF, Hubbard MA, et al. Cytochrome P450 phenotypic ratios for predicting herb-drug interactions in humans. Clin Pharmacol Ther 2002;72:276-87.. PubMed
  5. Yale SH, Glurich I. Analysis of the inhibitory potential of Ginkgo biloba, Echinacea purpurea, and Serenoa repens on the metabolic activity of cytochrome P450 3A4, 2D6, and 2C9. J Altern Complement Med 2005;11:433-9.
  6. Yasui-Furukori N, Furukori H, Kaneda A, et al. The effects of Ginkgo biloba extracts on the pharmacokinetics and pharmacodynamics of donepezil. J Clin Pharmacol 2004;44:538-42.
  7. Markowitz JS, Donovan JL, Lindsay DeVane C, et al. Multiple-dose administration of Ginkgo biloba did not affect cytochrome P-450 2D6 or 3A4 activity in normal volunteers. J Clin Psychopharmacol 2003;23:576-81. PubMed
  8. Wiegman DJ, Brinkman K, Franssen EJ. Interaction of Ginkgo biloba with efavirenz. AIDS 2009;23:1184-5. PubMed
  9. Naccarato M, Yoong D, Gough K. A potential drug-herbal interaction between Ginkgo biloba and efavirenz. J Int Assoc Physicians AIDS Care (Chic). 2012;11(2):98-100. doi: 10.1177/1545109711435364. Epub 2012 Feb 9.
  10. Robertson, S. M., Davey, R. T., Voell, J., Formentini, E., Alfaro, R. M., and Penzak, S. R. Effect of Ginkgo biloba extract on lopinavir, midazolam and fexofenadine pharmacokinetics in healthy subjects. Curr Med Res Opin 2008;24(2):591-599. PubMed
  11. Penzak, S. R., Busse, K. H., Robertson, S. M., Formentini, E., Alfaro, R. M., and Davey, R. T., Jr. Limitations of using a single postdose midazolam concentration to predict CYP3A-mediated drug interactions. J Clin Pharmacol 2008;48(6):671-680. PubMed
  12. Jalloh MA, Gregory PJ, Hein D, et al. Dietary supplement interactions with antiretrovirals: a systematic review. Int J STD AIDS. 2017 Jan;28(1):4-15. PubMed
  13. Bai J, Zhang C. Metabolic interaction between biflavonoids in Ginkgo biloba leaves and tacrolimus. Biopharm Drug Dispos 2023;44(2):157-164.
Moderate

ANTICOAGULANT/ANTIPLATELET DRUGS

5 of 6

Warfarin also falls under ANTICOAGULANT/ANTIPLATELET DRUGS.

Ginkgo has been shown to increase the risk of bleeding in some people when taken with warfarin. Theoretically, ginkgo might increase the risk of bleeding if used with other anticoagulant or antiplatelet drugs.
Several pharmacodynamic studies suggest that ginkgo inhibits platelet aggregation. It is thought that the ginkgo constituent, ginkgolide B, displaces platelet-activating factor (PAF) from its binding sites, decreasing blood coagulation. Several case reports have documented serious bleeding events in patients taking ginkgo. However, population and clinical studies have produced mixed results. Some evidence shows that short-term use of ginkgo leaf does not significantly reduce platelet aggregation and blood clotting. A study in healthy males who took a specific ginkgo leaf extract (EGb 761) 160 mg twice daily for 7 days found no change in prothrombin time. An analysis of a large medical record database suggests that ginkgo increases the risk of a bleeding adverse event by 38% when taken concurrently with warfarin. It has been suggested that ginkgo has to be taken for at least 2-3 weeks to have a significant effect on platelet aggregation. However, a meta-analysis of 18 studies using standardized ginkgo extracts, 80-480 mg daily for up to 32 weeks, did not find a significant effect on platelet aggregation, fibrinogen concentration, or PT/aPTT. In addition, a single dose of ginkgo plus clopidogrel or ticlopidine does not seem to significantly increase bleeding time or platelet aggregation. Also, taking ginkgo leaf extract daily for 8 days in conjunction with rivaroxaban does not affect anti-factor Xa activity; however, this study did not evaluate bleeding time.
Severity Moderate Likelihood Possible Evidence A

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the deal with these two together. Warfarin already lowers your blood's ability to clot, and ginkgo may add to that by making your platelets (the cells that help plug a cut) less sticky. Stack them and you could bruise more easily, see nosebleeds or bleeding gums, or in rarer cases have a more serious bleed.

I'll be honest, the research is mixed. Some studies found no real change in clotting tests, but one large database review showed about a 38% higher chance of a bleeding event when ginkgo and warfarin were taken together. Because warfarin is a narrow-window drug where small shifts matter, don't start or stop ginkgo without checking with your pharmacist or doctor first, and keep up with your INR checks.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Benjamin J, Muir T, Briggs K, Pentland B. A case of cerebral haemorrhage-can Ginkgo biloba be implicated? Postgrad Med J 2001;77:112-3.
  2. Rowin J, Lewis SL. Spontaneous bilateral subdural hemotomas with chronic Ginkgo biloba ingestion. Neurology 1996;46:1775-6.
  3. Rosenblatt M, Mindel T. Spontaneous hyphema associated with ingestion of Ginkgo biloba extract. N Engl J Med 1997;336:1108.
  4. Heck AM, DeWitt BA, Lukes AL. Potential interactions between alternative therapies and warfarin. Am J Health Syst Pharm 2000;57:1221-7. DOI
  5. Miller LG, Freeman B. Possible subdural hematoma associated with Ginkgo biloba. J Herb Pharmacother 2002;2:57-63.
  6. Kudolo GB, Dorsey S, Blodgett J. Effect of the ingestion of Ginkgo biloba extract on platelet aggregation and urinary prostanoid excretion in healthy and Type 2 diabetic subjects. Thromb Res 2002;108:151-60.. PubMed
  7. Kohler S, Funk P, Kieser M. Influence of a 7-day treatment with Ginkgo biloba special extract EGb 761 on bleeding time and coagulation: a randomized, placebo-controlled, double-blind study in healthy volunteers. Blood Coagul Fibrinolysis 2004;15:303–9. PubMed
  8. Destro MW, Speranzini MB, Cavalheiro Filho C, et al. Bilateral haematoma after rhytidoplasty and blepharoplasty following chronic use of Ginkgo biloba. Br J Plast Surg 2005;58:100-1. PubMed
  9. Bent S, Goldberg H, Padula A, Avins AL. Spontaneous bleeding associated with Ginkgo biloba: a case report and systematic review of the literature. J Gen Intern Med 2005;20;657-61. DOI
  10. Meisel C, Johne A, Roots I. Fatal intracerebral mass bleeding associated with Ginkgo biloba and ibuprofen. Atherosclerosis 2003;167:367. PubMed
  11. Bebbington A, Kulkarni R, Roberts P. Ginkgo biloba: Persistent bleeding after total hip arthroplasty caused by herbal self-medication. J Arthroplasty 2005;20:125-6. .
  12. Vale S. Subarachnoid haemorrhage associated with Ginkgo biloba. Lancet 1998;352:36. PubMed
  13. Aruna D, Naidu MU. Pharmacodynamic interaction studies of Ginkgo biloba with cilostazol and clopidogrel in healthy human subjects. Br J Clin Pharmacol 2007;63:333-8.
  14. Kim BH, Kim KP, Lim KS, et al. Influence of Ginkgo biloba extract on the pharmacodynamic effects and pharmacokinetic properties of ticlopidine: An open-label, randomized, two-period, two-treatment, two-sequence, single-dose crossover study in healthy Kor
  15. Kellermann AJ, Kloft C. Is there a risk of bleeding associated with standardized ginkgo biloba extract therapy? A systematic review and meta-analysis. Pharmacotherapy 2011;31:490-502.
  16. Bal Dit, Sollier C., Caplain, H., and Drouet, L. No alteration in platelet function or coagulation induced by EGb761 in a controlled study. Clin Lab Haematol. 2003;25(4):251-253. PubMed
  17. Kim, T. E., Kim, B. H., Kim, J., Kim, K. P., Yi, S., Shin, H. S., Lee, Y. O., Lee, K. H., Shin, S. G., Jang, I. J., and Yu, K. S. Comparison of the pharmacokinetics of ticlopidine between administration of a combined fixed-dose tablet formulation of ticl
  18. Pedroso, J. L., Henriques Aquino, C. C., Escorcio Bezerra, M. L., Baiense, R. F., Suarez, M. M., Dutra, L. A., Braga-Neto, P., and Povoas Barsottini, O. G. Ginkgo biloba and cerebral bleeding: a case report and critical review. Neurologist. 2011;17(2):89 PubMed
  19. Stoddard GJ, Archer M, Shane-McWhorter L, Bray BE, Redd DF, Proulx J, Zeng-Treitler Q. Ginkgo and Warfarin Interaction in a Large Veterans Administration Population. AMIA Annu Symp Proc. 2015 Nov 5;2015:1174-83.
  20. Hoerr R, Zimmermann A, Seitz F, Dienel A. Single and repeated doses of EGb 761® do not affect pharmacokinetics or pharmacodynamics of rivaroxaban in healthy subjects. Front Pharmacol. 2022 Apr 20;13:868843. PubMed
Moderate

WARFARIN (Coumadin)

6 of 6
Ginkgo has been shown to increase the risk of bleeding in some people when taken with warfarin.
Several pharmacodynamic studies suggest that ginkgo inhibits platelet aggregation. It is thought that the ginkgo constituent, ginkgolide B, displaces platelet-activating factor (PAF) from its binding sites, decreasing blood coagulation. Several case reports have documented serious bleeding events in patients taking ginkgo. Information from a medical database suggests that when taken concurrently with warfarin, ginkgo increases the risk of a bleeding adverse event by 38%. There is also some evidence that ginkgo leaf extract can inhibit cytochrome P450 2C9, an enzyme that metabolizes warfarin. This could result in increased warfarin levels. However, population and clinical research has produced mixed results. Clinical research in healthy people suggests that ginkgo has no effect on INR, or the pharmacokinetics or pharmacodynamics of warfarin. A meta-analysis of 18 studies using standardized ginkgo extracts, 80 mg to 480 mg daily for up to 32 weeks, did not find a significant effect on platelet aggregation, fibrinogen concentration, or PT/aPTT. There is also some preliminary clinical research that suggests ginkgo might not significantly increase the effects of warfarin in patients that have a stable INR.
Severity Moderate Likelihood Possible Evidence B

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the short version: combining ginkgo with warfarin may nudge your bleeding risk higher. Ginkgo can make your platelets a little less sticky, and one of its compounds may also slow down the liver enzyme (CYP2C9) that clears warfarin, which could let warfarin levels creep up. Since warfarin is a narrow therapeutic index drug, even small shifts can matter.

In real life that could show up as easier bruising, bleeding gums, nosebleeds, or blood in your urine or stool. That said, the evidence here is genuinely mixed. Several careful studies in stable patients found no real change in INR. So this is a possible concern, not a sure thing. Please don't start or stop either one on your own. Just give your pharmacist or doctor a heads up first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Benjamin J, Muir T, Briggs K, Pentland B. A case of cerebral haemorrhage-can Ginkgo biloba be implicated? Postgrad Med J 2001;77:112-3.
  2. Matthews, MK. Association of Ginkgo biloba with intracerebral hemorrhage. Neurology 1998;50:1934.
  3. Rowin J, Lewis SL. Spontaneous bilateral subdural hemotomas with chronic Ginkgo biloba ingestion. Neurology 1996;46:1775-6.
  4. Rosenblatt M, Mindel T. Spontaneous hyphema associated with ingestion of Ginkgo biloba extract. N Engl J Med 1997;336:1108.
  5. Heck AM, DeWitt BA, Lukes AL. Potential interactions between alternative therapies and warfarin. Am J Health Syst Pharm 2000;57:1221-7. DOI
  6. Miller LG, Freeman B. Possible subdural hematoma associated with Ginkgo biloba. J Herb Pharmacother 2002;2:57-63.
  7. Kudolo GB, Dorsey S, Blodgett J. Effect of the ingestion of Ginkgo biloba extract on platelet aggregation and urinary prostanoid excretion in healthy and Type 2 diabetic subjects. Thromb Res 2002;108:151-60.. PubMed
  8. Engelsen J, Nielsen JD, Winther K. Effect of coenzyme Q10 and Ginkgo biloba on warfarin dosage in stable, long-term warfarin treated outpatients. A randomised, double blind, placebo-crossover trial. Thromb Haemost 2002;87:1075-6. DOI
  9. Gaudineau C, Beckerman R, Welbourn S, Auclair K. Inhibition of human P450 enzymes by multiple constituents of the Ginkgo biloba extract. Biochem Biophys Res Comm 2004;318:1072–8. PubMed
  10. Jiang X, Williams KM, Liauw WS, et al. Effect of ginkgo and ginger on the pharmacokinetics and pharmacodynamics of warfarin in healthy subjects. Br J Clin Pharmacol 2005;59:425-32. PubMed
  11. Destro MW, Speranzini MB, Cavalheiro Filho C, et al. Bilateral haematoma after rhytidoplasty and blepharoplasty following chronic use of Ginkgo biloba. Br J Plast Surg 2005;58:100-1. PubMed
  12. Bent S, Goldberg H, Padula A, Avins AL. Spontaneous bleeding associated with Ginkgo biloba: a case report and systematic review of the literature. J Gen Intern Med 2005;20;657-61. DOI
  13. Meisel C, Johne A, Roots I. Fatal intracerebral mass bleeding associated with Ginkgo biloba and ibuprofen. Atherosclerosis 2003;167:367. PubMed
  14. Bebbington A, Kulkarni R, Roberts P. Ginkgo biloba: Persistent bleeding after total hip arthroplasty caused by herbal self-medication. J Arthroplasty 2005;20:125-6. .
  15. Vale S. Subarachnoid haemorrhage associated with Ginkgo biloba. Lancet 1998;352:36. PubMed
  16. Jiang X, Blair EY, McLachlan AJ. Investigation of the effects of herbal medicines on warfarin response in healthy subjects: a population pharmacokinetic-pharmacodynamic modeling approach. J Clin Pharmacol 2006;46:1370-8. PubMed
  17. Kellermann AJ, Kloft C. Is there a risk of bleeding associated with standardized ginkgo biloba extract therapy? A systematic review and meta-analysis. Pharmacotherapy 2011;31:490-502.
  18. Engelsen, J., Nielsen, J. D., and Hansen, K. F. [Effect of Coenzyme Q10 and Ginkgo biloba on warfarin dosage in patients on long-term warfarin treatment. A randomized, double-blind, placebo-controlled cross-over trial]. Ugeskr.Laeger 4-28-2003;165(18):18
  19. Pedroso, J. L., Henriques Aquino, C. C., Escorcio Bezerra, M. L., Baiense, R. F., Suarez, M. M., Dutra, L. A., Braga-Neto, P., and Povoas Barsottini, O. G. Ginkgo biloba and cerebral bleeding: a case report and critical review. Neurologist. 2011;17(2):89 PubMed
  20. Zhou, Y. and Zeng, R. [Effects of Ginkgo biloba extract on anticoagulation and blood drug level of warfarin in healthy wolunteers]. Zhongguo Zhong Yao Za Zhi 2011;36(16):2290-2293. DOI
  21. Stoddard GJ, Archer M, Shane-McWhorter L, Bray BE, Redd DF, Proulx J, Zeng-Treitler Q. Ginkgo and Warfarin Interaction in a Large Veterans Administration Population. AMIA Annu Symp Proc. 2015 Nov 5;2015:1174-83.

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Ginkgo Also Interacts With Other Medications

Ginkgo has 1 major, 1,264 moderate known drug interactions in our database — the Warfarin one above is among them. If you take anything else, check it against the full list below.

Major 1 Moderate 1,264 No known interaction 1,565 (incl. Warfarin)
Taking anything else?

Check Another of Your Medications Against Ginkgo

Covers the 2,830 medications we’ve checked against Ginkgo. Pick one to open its full report.

From our Q&A

Questions About Ginkgo or Warfarin

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Ginkgo or Warfarin, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Warfarin

This page covers Ginkgo only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Warfarin page lists 361 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Alfalfa (major), American Ginseng (major), Beer (major) and Cannabis (major).

By severity: 16 major · 301 moderate · 44 minor.

From our pharmacist’s overview on the Warfarin page

“People take warfarin to prevent dangerous clots, and many are the same people reaching for glucosamine for sore joints or a multivitamin containing vitamin K, which makes this a list that deserves genuine respect. Of the 361 supplements on file for warfarin, 16 carry a major rating, and the danger runs in both directions: some add to w…”

Reviewed by 2 · Jul 18, 2026

Open the Warfarin interaction page

One more smart check

Taking Ginkgo as Part of a Dietary Supplement Product? Check It for Interactions

We hold 4,399 real supplement products containing Ginkgo, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Ginkgo. Your product may carry other ingredients that interact with Warfarin too, on top of Ginkgo — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Ginkgo and Warfarin Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Ginkgo
Top 5%

#63 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Warfarin
Top 10

#5 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Ginkgo

What is Ginkgo?

Ginkgo
  • Memory and cognitive support
  • Age-related mental decline
  • Circulation problems
  • Tinnitus (ringing in the ears)
  • Dizziness or vertigo

Ginkgo is one of the world's most popular herbal supplements, mostly taken to support memory and circulation. The evidence for these uses is mixed and generally weak, and it is not proven to prevent memory loss or dementia. It is usually well tolerated in healthy adults, but it can thin the blood, so talk to your pharmacist or doctor before using it.

Read the full Ginkgo monograph & all interactions
Medication

About Warfarin

What Is Warfarin Used For?

Brand name: Warfarin

Warfarin sodium tablets and Jantoven tablets are both used to prevent and treat venous thrombosis (blood clots in the veins) and pulmonary embolism (a clot in the lungs). They are also used to prevent clot-related complications in people with atrial fibrillation (an irregular heart rhythm) or who have had a heart valve replaced.

In people who have had a heart attack, warfarin is used to reduce the risk of death, another heart attack, stroke, or other clotting events. It does not dissolve an existing clot, but it helps prevent the clot from growing and stops new dangerous clots from forming.

See full Warfarin drug information
Keep checking

Other Drugs & Ginkgo

Browse every other medication we’ve checked against Ginkgo — both the ones with a known interaction and the ones without. Select any drug for the full detail.

1Major
1,264Moderate
0Minor
1,564No known interaction
1 Major 1,264 Moderate 1,564 No interaction
Major

1 interaction

Moderate

1,264 interactions

Showing 60 of 1,264 moderate interactions — see all 1,264 on the Ginkgo page.

No interaction 1,564 drugs checked — show the list

We also checked Ginkgo against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 1,564 medications checked with no known interaction — see the full Ginkgo list.

See the full Ginkgo interactions page
See every supplement checked against Warfarin, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Ginkgo monograph › Uses, safety, and every drug interaction in one place Warfarin supplement interactions › Every supplement checked against Warfarin, ranked by severity Warfarin drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Ginkgo and Warfarin Together: Common Questions

Can you take Ginkgo with Warfarin?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
Why are there 6 interactions listed for Ginkgo and Warfarin?
Warfarin belongs to more than one drug category, and Ginkgo interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Ginkgo and Warfarin interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Warfarin and Ginkgo?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.