Ginkgo Biloba

📜 Historical Use

Ginkgo biloba is a deciduous tree so ancient it is commonly called a living fossil — the last remaining species of a primitive family of plants — which is also the origin of several of its names: fossil tree, maidenhair tree and Japanese silver apricot, alongside plain ginkgo. There is a real gap between what the plant was traditionally used for and what it is sold for now, and it is instructive. NCCIH records a long history of use in Chinese medicine for treating cough, diarrhoea and other conditions — nothing to do with memory. The modern identity is built instead on the standardised leaf extract, which is today the most commonly used form, promoted as a dietary supplement for anxiety, heart disease, cognitive impairment and dementia, diabetes, premenstrual syndrome, schizophrenia and tinnitus among others, and additionally promoted with claims that it can enhance cognitive performance in healthy people. Ginkgo's recent history is largely a research history, and an unusually well-funded one: the United States government paid to test the central claim through the NCCIH- and National Institute on Aging-funded Ginkgo Evaluation of Memory study, published by DeKosky and colleagues in JAMA in 2008, which followed more than 3,000 older adults for a median of six years and found no reduction in dementia. Few botanical supplements have had their headline indication tested that seriously; fewer still have kept selling as briskly after failing.

📊 What the Research Shows

Ginkgo has been studied more than most herbs, and the result is one of the clearest negatives in the field. NCCIH's bottom line is that there is no conclusive evidence ginkgo is helpful for any health condition, and that despite many studies it has not been shown to be effective for any of the conditions for which it has been studied. On dementia prevention — its flagship use — the evidence is not merely thin but actively negative. Three large studies in older adults with normal cognitive function or mild cognitive impairment found that ginkgo extract did not reduce the risk of dementia. The largest was the Ginkgo Evaluation of Memory study, funded by NCCIH and the National Institute on Aging, in which more than 3,000 people aged 75 or older were randomly assigned to ginkgo or placebo for a median of six years; there was no difference between the groups in the rates at which participants developed dementia of any type or Alzheimer's disease. For treating dementia symptoms once present, NCCIH allows that ginkgo may have a modest benefit, particularly at relatively high doses, but calls the evidence inconsistent, and says it is unclear whether ginkgo helps symptoms of milder cognitive impairment. For healthy people buying it for "brain health," it is uncertain whether it influences cognitive performance at all, and NCCIH notes much of that research is of low quality. Small, inconclusive signals exist for anxiety, premenstrual syndrome, schizophrenia and vertigo, and ginkgo might help in rehabilitation after stroke. Research suggests it is not helpful for preventing heart disease, for treating high blood pressure, or for relieving symptoms of tinnitus or multiple sclerosis.

Take 120-240mg of standardized extract divided into two doses daily.

Do not take if on blood thinners. Stop taking 2 weeks before surgery.

⚠️ What happens if taken in excess:

High doses (>240mg extract/day) or consumption of raw ginkgo seeds can cause seizures, bleeding, and allergic reactions. Raw ginkgo seeds contain ginkgotoxin (4'-O-methylpyridoxine) which causes convulsions — as few as 10 seeds can be toxic. Excessive supplementation can cause dangerous bleeding when combined with blood thinners. May cause headaches, dizziness, and GI upset at high doses.

The one interaction both sources support, and the one that matters, is bleeding. NCCIH states that ginkgo may increase the risk of bleeding in people taking anticoagulant drugs, naming warfarin specifically. LactMed supplies the mechanism that makes this plausible beyond warfarin alone — antiplatelet activity sufficient to have caused bleeding episodes in healthy volunteers taking ginkgo with nothing else. Read together, the concern is not confined to one drug but to the whole territory of impaired haemostasis, and NCCIH extends it into obstetrics with its warning about extra bleeding during delivery. Beyond that, honesty requires reporting an absence rather than filling it. NCCIH says only that ginkgo "may also interact with other drugs" without naming them, and neither source read for this page identifies a cytochrome P450 enzyme, a transporter, or any second named drug. This page therefore names warfarin and stops, rather than repeating the CYP claims that circulate widely for ginkgo; they may well be correct, but they are not in these two references and an unsourced enzyme is no better than an unsourced dose. One further caution is structural rather than pharmacological: LactMed notes that supplement labels and actual contents often differ in ingredients or amounts, so interaction findings for one ginkgo product do not automatically transfer to another.

1. Ginkgo: Usefulness and Safety — National Center for Complementary and Integrative Health NIH NCCIH (2025)[NIH ↗]
2. Ginkgo — Drugs and Lactation Database (LactMed) — National Institute of Child Health and Human Development NCBI Bookshelf (LactMed), NBK501809 (2025)[NIH ↗]
3. Ginkgo biloba for prevention of dementia: a randomized controlled trial — DeKosky ST, Williamson JD, Fitzpatrick AL, et al. JAMA (2008)[PubMed ↗]