Ginkgo Biloba

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

1. Birks J, Grimley Evans J. Ginkgo biloba for cognitive impairment and dementia. Cochrane Database Syst Rev. 2009;2009(1):CD003120. doi: 10.1002/14651858.CD003120.pub3.PubMedUsed to support: Cochrane systematic review pooling 36 randomized, double-blind, placebo-controlled trials in people with acquired cognitive impairment or dementia of any severity, most testing the standardized EGb 761 extract at high or low dose. Most trials were small and shorter than three months; the nine six-month trials (2,016 patients) were more recent and generally of adequate size. Results from the more recent trials varied from trial to trial for cognition, daily activities, mood, depression and carer burden: of the four most recent trials to report, three found no difference from placebo and one found very large effects. A subgroup of 925 people with Alzheimer's disease from nine trials showed no clear pattern of benefit. The reviewers concluded that the evidence of predictable, clinically significant benefit is unreliable, that many early trials used unsatisfactory methods, and that publication bias could not be excluded. Adverse events did not differ from placebo. A newer Cochrane review of the same question (Wieland 2026) has since been published.
2. Laws KR, Sweetnam H, Kondel TK. Is Ginkgo biloba a cognitive enhancer in healthy individuals? A meta-analysis. Hum Psychopharmacol. 2012;27(6):527-33. doi: 10.1002/hup.2259.PubMedUsed to support: Meta-analysis of randomized placebo-controlled trials of ginkgo in healthy adults with no cognitive impairment, pooling 1,132 participants for memory, 534 for executive function and 910 for attention. Effect sizes were close to zero and non-significant in all three domains, and meta-regression showed they were unrelated to participant age, trial duration, daily dose, total dose or sample size. The authors concluded ginkgo has no ascertainable positive effect on cognition in healthy people. It did not include people with cognitive impairment or dementia.
3. Nicolaï SP, Kruidenier LM, Bendermacher BL, Prins MH, Stokmans RA, Broos PP, Teijink JA. Ginkgo biloba for intermittent claudication. Cochrane Database Syst Rev. 2013;2013(6):CD006888. doi: 10.1002/14651858.CD006888.pub3.PubMedUsed to support: Systematic review of 14 randomized trials in 739 people with intermittent claudication caused by peripheral arterial disease. Pooling the 11 placebo-controlled trials with 477 participants, absolute claudication distance increased by the equivalent of about 64.5 meters on a flat treadmill, a difference that was not statistically significant, and the reviewers judged that publication bias had probably inflated even that figure. Their conclusion was that there is no evidence of clinically significant benefit for patients with peripheral arterial disease. All participants had diagnosed peripheral arterial disease, so it does not test effects in healthy people.
4. Hilton MP, Zimmermann EF, Hunt WT. Ginkgo biloba for tinnitus. Cochrane Database Syst Rev. 2013;2013(3):CD003852. doi: 10.1002/14651858.CD003852.pub3.PubMedUsed to support: Systematic review of four randomized trials with 1,543 participants, all assessed as being at low risk of bias. In the three trials totaling 1,143 people whose primary complaint was tinnitus, there was no evidence that ginkgo was effective. The single trial in 400 people with mild to moderate dementia who happened to have low-level tinnitus showed small reductions of 1.5 and 0.7 points on a 10 point scale in vascular dementia and Alzheimer's disease respectively, and the reviewers described the practical clinical significance of that as unclear. Side effect rates were low. A 2022 Cochrane update included 12 trials with 1,915 participants; it could pool only 85 participants for its main severity outcome and found ginkgo may have little to no effect, at low to very low certainty.
5. DeKosky ST, Williamson JD, Fitzpatrick AL, Kronmal RA, Ives DG, Saxton JA, Lopez OL, Burke G, Carlson MC, Fried LP, Kuller LH, Robbins JA, Tracy RP, Woolard NF, Dunn L, Snitz BE, Nahin RL, Furberg CD. Ginkgo biloba for prevention of dementia: a randomized controlled trial. JAMA. 2008;300(19):2253-62. doi: 10.1001/jama.2008.683.PubMedUsed to support: Randomized, double-blind, placebo-controlled trial (the Ginkgo Evaluation of Memory study) at 5 US academic centers in 3,069 community volunteers aged 75 or older with normal cognition (2,587) or mild cognitive impairment (482), given 120 mg of EGb 761 twice daily or placebo for a median 6.1 years, with dementia diagnosed by expert panel consensus. Dementia developed in 277 people on ginkgo and 246 on placebo (hazard ratio 1.12, 95% CI 0.94 to 1.33); the hazard ratio for Alzheimer's disease was 1.16 (0.97 to 1.39), and ginkgo did not slow progression to dementia in those with mild cognitive impairment (1.13, 0.85 to 1.50). Dropout and loss to follow-up were 6.3 percent and adverse effect profiles were similar. The full text reports that major bleeding did not differ (hazard ratio 0.97), with 16 hemorrhagic strokes on ginkgo versus 8 on placebo (not significant). Funding came from NIH (NCCAM, Office of Dietary Supplements, National Institute on Aging and others); Schwabe Pharmaceuticals donated the tablets and placebo and had no role in design, analysis or the manuscript.
6. Snitz BE, O'Meara ES, Carlson MC, Arnold AM, Ives DG, Rapp SR, Saxton J, Lopez OL, Dunn LO, Sink KM, DeKosky ST. Ginkgo biloba for preventing cognitive decline in older adults: a randomized trial. JAMA. 2009;302(24):2663-70. doi: 10.1001/jama.2009.1913.PubMedUsed to support: Prespecified cognitive analysis of the same 3,069 participant GEM trial (ages 72 to 96, median 6.1 years, 120 mg twice daily versus placebo), tracking rates of change on the Modified Mini-Mental State Examination, the ADAS-Cog and neuropsychological domains of memory, attention, visuospatial ability, language and executive function. Annual rates of decline did not differ between ginkgo and placebo in any domain (for example memory 0.043 versus 0.041 z score units per year), and there were no between-group differences on the 3MSE (P = .71) or ADAS-Cog (P = .97). No effect modification was found by age, sex, race, education, APOE e4 status or baseline mild cognitive impairment.
7. Vellas B, Coley N, Ousset PJ, Berrut G, Dartigues JF, Dubois B, Grandjean H, Pasquier F, Piette F, Robert P, Touchon J, Garnier P, Mathiex-Fortunet H, Andrieu S. Long-term use of standardised Ginkgo biloba extract for the prevention of Alzheimer's disease (GuidAge): a randomised placebo-controlled trial. Lancet Neurol. 2012;11(10):851-9. doi: 10.1016/S1474-4422(12)70206-5.PubMedUsed to support: Randomized, double-blind, placebo-controlled GuidAge trial in France enrolling 2,854 adults aged 70 or older who spontaneously reported memory complaints to their primary care physician, given 120 mg of EGb 761 twice daily or matched placebo and followed for 5 years. Probable Alzheimer's disease was diagnosed in 61 people on ginkgo (1.2 per 100 person-years) versus 73 on placebo (1.4 per 100 person-years; hazard ratio 0.84, 95% CI 0.60 to 1.18; p = 0.306), though the risk was not proportional over time. Adverse events, deaths (76 versus 82), strokes (65 versus 60) and other hemorrhagic or cardiovascular events did not differ between groups. The trial was funded by Ipsen.
8. Wieland LS, Ludeman E, Chi Y, Feinberg TM, Chen IH, Chen KH, Zhu Y, Wolverson E, Amri H. Ginkgo biloba for cognitive impairment and dementia. Cochrane Database Syst Rev. 2026;2(2):CD013661. doi: 10.1002/14651858.CD013661.pub2.PubMedUsed to support: Current Cochrane systematic review of ginkgo for cognitive impairment and dementia: 82 randomized trials with 10,613 participants (72 with extractable data), of which only four were at low risk of bias in all domains. In mild cognitive impairment (12 trials, 1,913 participants), ginkgo probably has little or no effect at six months on global clinical status, cognition or daily activities (moderate certainty). In people with subjective memory complaints the effect on global status is uncertain, and one three-month trial found adverse events may be more common with ginkgo. In multiple sclerosis with cognitive problems (2 trials), ginkgo probably has little or no effect on cognition. In people with dementia (13 trials, 3,288 participants), low-certainty evidence suggests small to moderate six-month benefits on global status, cognition (Syndrom-Kurztest) and daily activities, with very high heterogeneity between trials (I squared 88 to 96 percent). Serious adverse events did not differ from placebo.
9. Kuller LH, Ives DG, Fitzpatrick AL, Carlson MC, Mercado C, Lopez OL, Burke GL, Furberg CD, DeKosky ST. Does Ginkgo biloba reduce the risk of cardiovascular events? Circ Cardiovasc Qual Outcomes. 2010;3(1):41-7. doi: 10.1161/CIRCOUTCOMES.109.871640.PubMedUsed to support: Preplanned secondary cardiovascular analysis of the 3,069 participant GEM trial (120 mg EGb 761 twice daily versus placebo, mean 6.1 years), with events classified by Cardiovascular Health Study methods. Of 355 deaths, 87 were from coronary heart disease, with no difference between groups; there were no differences in myocardial infarction (164 events), angina (207) or stroke (151). There were 16 hemorrhagic strokes on ginkgo and 8 on placebo (not significant), and 12 peripheral vascular disease events on ginkgo versus 23 on placebo (P = 0.04). The authors concluded ginkgo cannot be recommended for preventing cardiovascular disease and that further trials of peripheral vascular outcomes might be indicated.
10. 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(5):490-502. doi: 10.1592/phco.31.5.490.PubMedUsed to support: Meta-analysis of 18 randomized controlled trials in 1,985 adults, 87 percent of whom were patients with dementia, peripheral artery disease or diabetes rather than healthy volunteers, examining whether standardized ginkgo extract changes the blood measurements that predict bleeding. Ginkgo significantly reduced blood viscosity but had no significant effect on ADP-induced platelet aggregation, fibrinogen concentration, activated partial thromboplastin time or prothrombin time. Small shortenings of clotting time in the subgroups taking 240 mg per day or more were judged not clinically relevant. It measures laboratory parameters rather than counting actual bleeding events, so it reduces rather than eliminates the concern raised by published case reports.
11. Bent S, Goldberg H, Padula A, Avins AL. Spontaneous bleeding associated with ginkgo biloba: a case report and systematic review of the literature: a case report and systematic review of the literature. J Gen Intern Med. 2005;20(7):657-61. doi: 10.1111/j.1525-1497.2005.0121.x.PubMedUsed to support: Systematic review of published case reports of bleeding in people taking ginkgo, identifying 15 reports with a temporal association, including 8 episodes of intracranial bleeding, and elevated bleeding times in the three cases where this was measured. The reviewers judged a possible causal association. The limitations are the reason this cannot settle the question on its own: 13 of the 15 patients had other identifiable bleeding risk factors, and only 6 reports documented both that ginkgo was stopped and that bleeding did not recur. Case reports cannot establish causation or estimate how often this happens, which is why this evidence sits alongside, rather than above, the randomized trial data on clotting parameters.
12. Jiang X, Williams KM, Liauw WS, Ammit AJ, Roufogalis BD, Duke CC, Day RO, McLachlan AJ. Effect of ginkgo and ginger on the pharmacokinetics and pharmacodynamics of warfarin in healthy subjects. Br J Clin Pharmacol. 2005;59(4):425-32. doi: 10.1111/j.1365-2125.2005.02322.x.PubMedUsed to support: Open-label, randomized, three-way crossover study in 12 healthy men given a single 25 mg dose of warfarin alone or after 7 days of pretreatment with recommended doses of a ginkgo or ginger product of known quality, continued for 7 days after the warfarin dose. Ginkgo alone did not affect INR or platelet aggregation, and with warfarin it did not change S- or R-warfarin clearance, INR area under the curve (ratio 0.93), protein binding or CYP2C9 activity. It studied 12 healthy men after a single warfarin dose, not patients on long-term anticoagulation.
13. Kupiec T, Raj V. Fatal seizures due to potential herb-drug interactions with Ginkgo biloba. J Anal Toxicol. 2005;29(7):755-8. doi: 10.1093/jat/29.7.755.PubMedUsed to support: Case report of a 55-year-old man who died of a breakthrough seizure with no evidence of missed anticonvulsant doses; autopsy showed subtherapeutic blood levels of both valproate (Depakote) and phenytoin (Dilantin). He was self-medicating with many herbal supplements, prominently ginkgo. The authors cite a study showing ginkgo induces CYP2C19, which helps metabolize both drugs, as a plausible explanation, note that ginkgo nuts contain a neurotoxin known to induce seizures, and identify one other documented instance of ginkgo apparently promoting seizure activity during anticonvulsant therapy. A single case with several supplements involved cannot establish causation.
14. Sereda M, Xia J, Scutt P, Hilton MP, El Refaie A, Hoare DJ. Ginkgo biloba for tinnitus. Cochrane Database Syst Rev. 2022;11(11):CD013514. doi: 10.1002/14651858.CD013514.pub2.PubMedUsed to support: Current Cochrane systematic review of ginkgo for tinnitus: 12 randomized trials with 1,915 participants (11 versus placebo, one with hearing aids). Pooling two trials with 85 participants, ginkgo may have little to no effect on Tinnitus Handicap Inventory scores at three to six months (mean difference -1.35 on a 0 to 100 scale, 95% CI -8.26 to 5.55; very low certainty). Single trials found little to no difference in tinnitus loudness or health-related quality of life. Risk of bias was high or unclear in most trials, certainty ranged from low to very low, and the reviewers stressed the strong placebo response in tinnitus. No serious adverse effects, including bleeding or seizures, were reported in either group across 4 trials with 1,154 participants.
15. Evans JR. Ginkgo biloba extract for age-related macular degeneration. Cochrane Database Syst Rev. 2013;2013(1):CD001775. doi: 10.1002/14651858.CD001775.pub2.PubMedUsed to support: Systematic review of randomized trials of ginkgo extract for age-related macular degeneration, which located only two trials randomizing 119 people in total, both lasting six months: a French study of 20 people given EGb 761 at 160 mg per day versus placebo, and a German study of 99 people comparing two doses of EGb 761 with no placebo arm. Both reported some positive effect on vision, but the results could not be pooled and neither reported adverse effects or quality of life. The reviewer's conclusion was that whether people with macular degeneration should take ginkgo has not been answered by research to date. The reviewer called for larger and longer trials.
16. Quaranta L, Bettelli S, Uva MG, Semeraro F, Turano R, Gandolfo E. Effect of Ginkgo biloba extract on preexisting visual field damage in normal tension glaucoma. Ophthalmology. 2003;110(2):359-62; discussion 362-4. doi: 10.1016/S0161-6420(02)01745-1.PubMedUsed to support: Randomized, placebo-controlled, double-masked crossover trial in 27 patients with bilateral visual field damage from normal tension glaucoma, given 40 mg of ginkgo extract three times daily for 4 weeks, an 8 week washout and 4 weeks of placebo, or the reverse order. Visual field mean deviation and corrected pattern standard deviation improved significantly after the ginkgo phase compared with baseline, with no change in intraocular pressure, blood pressure or heart rate. A later randomized crossover trial in 35 patients at the same dose and schedule, with 80 percent power to detect a difference this large, found no effect.
17. Guo X, Kong X, Huang R, Jin L, Ding X, He M, Liu X, Patel MC, Congdon NG. Effect of Ginkgo biloba on visual field and contrast sensitivity in Chinese patients with normal tension glaucoma: a randomized, crossover clinical trial. Invest Ophthalmol Vis Sci. 2014;55(1):110-6. doi: 10.1167/iovs.13-13168.PubMedUsed to support: Randomized, placebo-controlled, crossover trial in 35 Chinese patients newly diagnosed with normal tension glaucoma, using the same regimen as the earlier positive study: 40 mg of ginkgo extract three times daily for 4 weeks, an 8 week washout, then 4 weeks of the other treatment, with the order randomized. Changes in visual field mean deviation and in contrast sensitivity did not differ by treatment received or by sequence, and the trial had 80 percent power to detect a difference as large as the one previously reported. The authors noted that this result contrasts with some previous reports. Its limitations are that 35 patients (28 completed testing) is a small trial and each phase lasted only 4 weeks, so it does not exclude a benefit that takes longer than a month to appear.
18. Prinz J, Prokosch V, Wang X, Feng Y, Walter P, Fuest M, Migliorini F. Efficacy of Ginkgo biloba on parameters in glaucoma: A systematic review. PLoS One. 2025;20(2):e0314644. doi: 10.1371/journal.pone.0314644.PubMedUsed to support: Systematic review pooling 8 studies with 428 patients of average age 51 and a median follow-up under 4 months, covering ginkgo extract given both to people with glaucoma and to healthy volunteers. Ginkgo was not associated with any change in intraocular pressure, visual field mean deviation, corrected pattern standard deviation or heart rate, either from baseline or in comparison with control groups. The reviewers concluded that the evidence is not sufficient to conclude that ginkgo affects any of these measures. The reviewers advised caution because of the short follow-up of the included studies.
19. Bredie SJ, Jong MC. No significant effect of ginkgo biloba special extract EGb 761 in the treatment of primary Raynaud phenomenon: a randomized controlled trial. J Cardiovasc Pharmacol. 2012;59(3):215-21. doi: 10.1097/FJC.0b013e31823c0bed.PubMedUsed to support: Randomized, double-blind, placebo-controlled trial in 41 people with primary Raynaud's disease, given 120 mg of the standardized EGb 761 extract twice daily or placebo for 10 weeks after a 2 week run-in period. Daily attack frequency fell by 33 percent on ginkgo and 31 percent on placebo, a difference that was not significant, and there was no difference in the duration or severity of attacks either. Tolerability was good, with fewer adverse events reported on ginkgo than on placebo. The authors described it as a pilot study, and with 41 patients it cannot rule out a small benefit.
20. Fowler JS, Wang GJ, Volkow ND, Logan J, Franceschi D, Franceschi M, MacGregor R, Shea C, Garza V, Liu N, Ding YS. Evidence that gingko biloba extract does not inhibit MAO A and B in living human brain. Life Sci. 2000;66(9):PL141-6. doi: 10.1016/s0024-3205(99)00660-8.PubMedUsed to support: Brain imaging study in 10 people who took 120 mg per day of the EGb 761 extract for one month, using PET scanning with two radiotracers to measure the activity of monoamine oxidase A and monoamine oxidase B directly in the living human brain. Neither enzyme was inhibited. The authors note that ginkgo extracts had been reported to inhibit both enzymes in rat brain in vitro, leading to speculation that this contributes to its effects on the brain, and conclude that other mechanisms need to be considered. The study covered 10 people at one dose for one month.
21. Woelk H, Arnoldt KH, Kieser M, Hoerr R. Ginkgo biloba special extract EGb 761 in generalized anxiety disorder and adjustment disorder with anxious mood: a randomized, double-blind, placebo-controlled trial. J Psychiatr Res. 2007;41(6):472-80. doi: 10.1016/j.jpsychires.2006.05.004.PubMedUsed to support: Randomized, double-blind, placebo-controlled trial in 107 patients with generalized anxiety disorder (82) or adjustment disorder with anxious mood (25), given 480 mg or 240 mg per day of EGb 761 or placebo for 4 weeks. Hamilton anxiety scale scores fell by 14.3, 12.1 and 7.8 points respectively; both doses differed significantly from placebo (p = 0.0003 and p = 0.01), with a dose-response trend, and EGb 761 was superior to placebo on all secondary outcomes. It is one short trial of a single branded extract, and the abstract does not state who funded it.
22. Muir AH, Robb R, McLaren M, Daly F, Belch JJ. The use of Ginkgo biloba in Raynaud's disease: a double-blind placebo-controlled trial. Vasc Med. 2002;7(4):265-7. doi: 10.1191/1358863x02vm455oa.PubMedUsed to support: Double-blind, placebo-controlled trial of a standardized ginkgo phytosome extract (Seredrin) in people with primary Raynaud's disease, treated for 10 weeks after a 2 week diary baseline. Attacks per week fell by 56 percent on ginkgo versus 27 percent on placebo, and attack frequency was the only outcome where treatment beat placebo. Blood rheology measures did not differ between groups. The abstract does not report the number of participants, and a later placebo-controlled trial of the EGb 761 extract in 41 patients did not reproduce the reduction in attack frequency.
23. Biber A. Pharmacokinetics of Ginkgo biloba extracts. Pharmacopsychiatry. 2003;36 Suppl 1:S32-7. doi: 10.1055/s-2003-40446.PubMedUsed to support: Review by a research scientist at Dr. Willmar Schwabe, the maker of EGb 761. States that EGb 761 is standardized to keep flavonol glycosides at 22 to 27 percent and terpene lactones at 5 to 7 percent, with ginkgolic acids below 5 parts per million, and summarizes the pharmacokinetics of these constituents. Written by the manufacturer.
24. Committee on Herbal Medicinal Products (HMPC), European Medicines Agency. European Union herbal monograph on Ginkgo biloba L., folium (EMA/HMPC/321097/2012). European Medicines Agency. 2015;Final monograph adopted 28 January 2015 (not PubMed-indexed)..SourceUsed to support: Not PubMed-indexed: EU regulatory monograph. Lists 240 mg per day of refined leaf dry extract for at least 8 weeks. Undesirable effects: headache very common; dizziness, diarrhea, abdominal pain, nausea and vomiting common; bleeding of the eye, nose, brain and gut, allergic shock and allergic skin reactions with frequency not known. Advises stopping 3 to 4 days before surgery, consulting a doctor with a bleeding tendency or anticoagulant or antiplatelet treatment, notes that further seizures cannot be excluded in epilepsy, contraindicates use in pregnancy and does not recommend it during breastfeeding. Interactions: anticoagulant and antiplatelet effects may be influenced; caution with dabigatran (intestinal P-glycoprotein); nifedipine peak levels raised up to 100 percent in some people; use with efavirenz not recommended (CYP3A4 induction).
25. National Center for Complementary and Integrative Health (NCCIH), National Institutes of Health. Ginkgo NCCIH Health Topics. 2025;Fact sheet, last updated February 2025 (not PubMed-indexed)..SourceUsed to support: Not PubMed-indexed: US government fact sheet. States that the most common side effects of ginkgo leaf extract are dizziness, gastrointestinal symptoms and headache; that ginkgo may increase bleeding risk in people taking anticoagulants such as warfarin; that fresh ginkgo seeds are toxic and serious side effects have occurred with roasted seeds; that ginkgo may be unsafe in pregnancy and might cause early labor or extra bleeding during delivery; and that ginkgo has not been shown to prevent or slow dementia.