Ginkgo biloba

Q: What is ginkgo biloba?

Ginkgo biloba is a tree native to China. The supplement is usually a standardised extract of its leaves, sold as capsules, tablets or drops.

Q: Does ginkgo improve memory?

Not in healthy adults. A pooled analysis of trials found effects close to zero for memory, and a six-week trial in healthy adults over 60 found no difference from placebo.

Q: Does ginkgo prevent dementia or Alzheimer disease?

Two large trials in older adults found it did not. NCCIH says three large studies found no reduction in dementia risk.

Q: Does ginkgo help mild cognitive impairment?

Probably not. Cochrane found little or no effect on overall status, thinking or daily activities at six months, with moderate certainty.

Q: Does ginkgo increase bleeding?

The evidence is mixed. Trial data on clotting tests showed no effect, but a large records study linked ginkgo plus warfarin to more bleeding, and there are case reports. NCCIH warns about anticoagulants.

Q: Can I take ginkgo with warfarin or aspirin?

Ask your doctor or pharmacist first. NCCIH warns of bleeding risk with anticoagulants such as warfarin. A crossover study found no change in warfarin handling, while a records study found more bleeding.

Q: Are ginkgo seeds safe to eat?

No. NCCIH says fresh seeds are toxic. Case reports describe seizures after eating large amounts of seeds or nuts.

Q: Is ginkgo safe in pregnancy or breastfeeding?

NCCIH says ginkgo may be unsafe in pregnancy and, near delivery, might cause early labour or extra bleeding. Safety while breastfeeding is not well known. Ask a doctor first.

Q: What are the side effects?

NCCIH says leaf extract is generally well tolerated; the most common side effects are dizziness, stomach or gut upset and headache.

Ginkgo biloba · also called Ginkgo, maidenhair tree

Ginkgo biloba is a tree from China whose leaf extract is sold as a memory supplement. Two large trials in older adults found it did not prevent dementia or slow memory decline, and it showed no memory benefit in healthy people; any help for people who already have dementia is uncertain. The main caution is bleeding, especially with blood thinners, and the seeds are poisonous.

General information, not medical advice. Last substantive update October 26, 2026 · Not medically reviewed. A named clinician has not signed off on this page. How this page is made

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About Ginkgo biloba

Ginkgo leaf extract is widely sold for memory. Large trials in older adults found no protection against dementia, bleeding is the main caution, and seeds are poisonous.

What ginkgo is

Ginkgo biloba is a tree native to China. Supplements are made from its leaves, usually as a concentrated, standardised extract sold as capsules, tablets or drops. The best-known extract is called EGb 761. This page covers the leaf extract as a memory supplement. The tree, tea and traditional uses are on the ginkgo herb page.

Ginkgo is not an essential nutrient, so there is no deficiency to correct.

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What the large trials found

The two largest trials ran for years in older adults and found no protection. In the US GEM trial (3,069 people aged 75 or older, about 6 years), 277 people on ginkgo and 246 on placebo developed dementia, so ginkgo did not lower the risk, and it did not slow the yearly decline in memory either. In the French GuidAge trial (2,854 people aged 70 or older with memory complaints, 5 years), the Alzheimer difference between ginkgo and placebo was also not significant. NCCIH, a US government centre, says three large studies found no reduction in dementia risk.

In healthy adults, a pooled analysis found no memory benefit. In mild cognitive impairment, the 2026 Cochrane review found little or no effect. The one area with a hint of benefit is people who already have dementia, but Cochrane rates that evidence low-certainty, with very large differences between trials. Ginkgo is not a cure or a proven treatment for dementia.

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Bleeding cautions

NCCIH warns that ginkgo may increase bleeding risk in people on anticoagulants such as warfarin. The evidence is mixed: pooled trial data on clotting tests showed no effect, and a crossover study found no change in warfarin levels or INR, but a large records study of US Veterans linked ginkgo plus warfarin to more bleeding events, and there are case reports of bleeding. Records studies cannot prove cause.

If you take a blood thinner, have a bleeding problem, or are having surgery or dental work, tell your doctor or pharmacist about ginkgo first.

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Seeds are different from leaf extract

NCCIH says fresh ginkgo seeds are toxic when eaten. Case reports describe vomiting, diarrhoea and seizures in a 2-year-old girl and in an adult after eating large amounts of seeds or nuts. The seeds contain a vitamin B6 blocker. Seeds are a separate food with their own page; do not confuse them with the extract.

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Product quality

A 2024 review of published tests found that 56.7% of 533 ginkgo leaf samples were adulterated or mislabelled, the highest rate among five popular herbs. The authors warn that the data have limits, and that licensed herbal medicines had a lower risk than food supplements. The label alone does not guarantee what is in a product.

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Extract versus tea or food

The trial results here are for standardised leaf extract. They do not apply to tea, raw leaf or seeds. This page gives no amounts to take; if you wonder whether ginkgo is right for you, ask a doctor or pharmacist.

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At a glance

Traditional uses history, not proof

Leaf and seed used in Chinese medicine
Leaf extract sold as a memory and circulation supplement

Studied for research

Preventing dementia, evidence against
Slowing memory decline with age, evidence against
Memory in healthy adults, evidence against
Mild cognitive impairment, evidence against
Symptoms in dementia, low certainty
Tinnitus, very low certainty
Leg pain on walking, low certainty
Altitude sickness, mixed

Main compounds

Ginkgolides and bilobalide (terpene lactones)
Flavonol glycosides
Ginkgolic acid

Common forms

Standardised leaf extract (capsules, tablets, drops)
Leaf tea or powder
Seeds (poisonous raw)

Research links: 2008 GEM trial: ginkgo for preventing dementia (3,069 people) · 2012 GuidAge trial: ginkgo for preventing Alzheimer disease · 2026 Cochrane review: ginkgo for cognitive impairment and dementia · 2011 meta-analysis: ginkgo and bleeding risk · NCCIH: Ginkgo · Research Library · Genes & Biomarkers Library

What it is and its history

Accepted scientific name: Ginkgo biloba L. (the leaf extract is the supplement ingredient)
Naming authority: L., published in Mant. Pl. 2: 313 (1771) (GBIF)
Common names: Ginkgo (English); Maidenhair tree (English); Gingko (variant spelling) (English); Common ginkgo (English)
Family or group: Ginkgoaceae. A genetics paper says Ginkgo biloba is the only species of its genus that survives today.
Classification: Plantae > Tracheophyta > Ginkgoopsida > Ginkgoales > Ginkgoaceae > Ginkgo > Ginkgo biloba
Native range: Native to China; spread by people to temperate regions less than about 300 years ago (genetics paper).
Habitat: Not verified in the sources read.
What it looks like: Leaves: The leaf is the part used for supplement extracts. Leaf shape was not verified in a cited source.; Fruit: The seed (often called a nut) is a separate food and is poisonous when raw (NCCIH).
Harvest and processing: Supplement extracts are concentrated and standardised; the trials read used standardised extracts, such as EGb 761 in GuidAge.
Look-alikes and adulterants: Name: Ginkgo herb profile; Note: The plant, tea and tradition are covered on the herb page for ginkgo in Herbs & Botanicals; this page covers the standardised extract sold as a memory supplement.; Name: Ginkgo seeds / nuts; Note: A separate, poisonous-when-raw food with its own page in Nuts and Seeds.
Sustainability and conservation: Not assessed.

Traditional use and history history, not clinical proof

Tradition or era	Documented use	Source
Chinese medicine and spread of the tree	A review calls the ginkgo the oldest living tree with a long history in Chinese medicine, and a genetics paper says people spread it beyond China less than 300 years ago. Specific traditional uses and dates were not verified here.	p15038029

Traditional use shows how it was used. It does not show that it works or is safe today.

What is inside, and how it may work

What it contains and how those compounds act in cells and animals. Laboratory and animal mechanisms are not proven effects in people.

Main compounds

Compound	Family	Where it is concentrated	Activity studied	Level of evidence
Ginkgolides A, B, C and J, and bilobalide (terpene lactones)	terpene trilactones	Leaf In an extract tested by the US National Toxicology Program: 15.4% terpene lactones, including 3.74% ginkgolide A and 1.62% ginkgolide B.	A chemistry review says these are the most unusual components of the extracts and are believed to explain part of the effect on nerve signalling. A human study found ginkgolide A and B reach higher blood levels than C and J, and that changes in the blood form lowered their lab activity against platelet-activating factor. ^{23 12 15}	Human data
Flavonol glycosides (flavonoids)	flavonoids	Leaf The extract tested by the NTP contained 31.2% flavonol glycosides.	No clinical effect of the flavonoids alone was read. ¹⁵	Laboratory research
Ginkgolic acid	alkylphenols	Not stated in the source read The NTP test extract contained 10.45 ppm.	Not researched here beyond content. ¹⁵	Unknown

Mechanisms, receptors and pathways

Target or pathway	Gene or receptor	What was found	Level
Platelet-activating factor (PAF) receptor	Not specified	Ginkgolides A, B and C block PAF in lab tests, and changes to the molecules in the blood reduce this activity. This is a possible link to bleeding but is not shown to cause bleeding in people. ¹²	Laboratory research
Brain signalling	Not specified	A chemistry review says terpene lactones are believed to be partly responsible for effects on nerve signalling. How or whether this affects memory in people has not been shown. ²³	Laboratory research

Absorption, metabolism and elimination

Absorption: In humans given a ginkgo tablet, ginkgolides A and B and bilobalide reached higher blood levels than ginkgolides C and J.
Distribution: Terpene lactones spread fairly evenly through body fluids and tissues; the unbound fraction in plasma was 45 to 92%.
Metabolism: In the blood the compounds exist as the original rings and as opened monocarboxylate forms.
Elimination: Kidney filtration is the main route for ginkgolides and a major route for bilobalide; half-lives were about 4 to 13 hours.
Bioavailability: Apparent oral bioavailability of ginkgolides A and B was mostly over 100%; C and J, 6 to 15%.

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Isolated compounds versus whole extracts

The trials read tested standardised leaf extracts (EGb 761 in GuidAge and many dementia trials), not tea, raw leaf or seeds. Seeds are toxic and are a separate food. Do not assume tea or an unstandardised product acts the same way; quality is also inconsistent.

Nutritional composition

Ginkgo is not an essential nutrient. Unlike vitamins and minerals, there is no deficiency state. Ginkgo seeds are eaten as a traditional food in parts of Asia (per a 2002 case report) but raw seeds are poisonous (NCCIH). Food amounts were not researched.

8benefits and uses looked at

30studies and sources checked

Low certaintybest evidence rating found

7lab markers tracked in trials

1 mixed findings2 low certainty1 very low certainty4 evidence against

What was looked at

The 8 benefits and uses checked for Ginkgo biloba, each with how strong the evidence is. Tap one to open it.

Preventing dementia in older adultsEvidence against
Slowing memory and thinking decline with ageEvidence against
Memory in healthy adultsEvidence against
Mild cognitive impairment (MCI)Evidence against
Symptoms in people who already have dementiaLow certainty
Ringing in the ears (tinnitus)Very low certainty
Leg pain when walking (intermittent claudication)Low certainty
Preventing altitude sicknessMixed findings

Lab markers tracked in the studies

New cases of dementiaYearly decline in memory scoresMemory test scores in healthy adultsShort Cognitive Performance Test (SKT) in dementiaTinnitus Handicap Inventory scoreWalking distanceChance of acute mountain sickness

What is Ginkgo biloba good for?

The studied uses and how strong the human evidence is for each. Most results come from one type of product, a standardised leaf extract.

Preventing dementia in older adultsEvidence againstEvidence against. Two large trials in older adults (3,069 people for about 6 years, and 2,854 people for 5 years) found ginkgo extract did not lower the chance of dementia or Alzheimer disease. Slowing memory and thinking decline with ageEvidence againstEvidence against. In the US trial of people aged 72 to 96, ginkgo did not slow yearly decline in memory, attention, language or planning. Memory in healthy adultsEvidence againstEvidence against. A pooled analysis found effects close to zero for memory, planning and attention in healthy adults, and a six-week trial in healthy adults over 60 found no difference. Mild cognitive impairment (MCI)Evidence againstEvidence against, with moderate certainty. In mild cognitive impairment, ginkgo probably has little or no effect on overall status, thinking or daily activities at six months. Symptoms in people who already have dementiaLow certaintyLow-certainty hints of small to moderate help in people who already have dementia, with very large differences between trials. Not a proven treatment. Ringing in the ears (tinnitus)Very low certaintyVery uncertain. Pooled trials found little or no difference in tinnitus severity. Leg pain when walking (intermittent claudication)Low certaintyA small, not significant gain in walking distance; the review authors found no clinically significant benefit. Preventing altitude sicknessMixed findingsMixed. A trend toward fewer cases that was not statistically significant, with conflicting trials.

Benefits, one by one

Each card is a research question, not a promise. Tap a goal to filter. Open a card to see the studies, doses and limits.

Preventing dementia in older adults

Evidence against

Two large, long trials in older adults found that ginkgo extract did not lower the chance of getting dementia or Alzheimer disease. The US trial (3,069 people aged 75 or older, median 6.1 years) found slightly more dementia on ginkgo than on placebo, though not a clear difference.

3 studiesOne standardised extract (EGb 761 in GuidAge) at one trial amount; te…

Studies, doses and limits

What the trials found

GEM trial (JAMA 2008): 523 people developed dementia, 277 on ginkgo and 246 on placebo (HR 1.12, 95% CI 0.94 to 1.33). It also did not slow the move from mild cognitive impairment to dementia. GuidAge trial (Lancet Neurology 2012, 2,854 people aged 70 or older with memory complaints, 5 years): 61 people on ginkgo and 73 on placebo were diagnosed with probable Alzheimer disease (HR 0.84, 95% CI 0.60 to 1.18), also not a significant difference. NCCIH (page updated February 2025) says three large studies in older adults found no reduction in dementia risk.

Results

Ginkgo extract did not prevent dementia in two large randomised trials. This is evidence against a protective effect, in older adults, for the extract studied.

Effect sizes as reported

GEM: all-cause dementia HR 1.12 (0.94 to 1.33); Alzheimer HR 1.16 (0.97 to 1.39). GuidAge: HR 0.84 (0.60 to 1.18).

Why this rating

Two large, well-run placebo-controlled trials (about 5,900 people) both found no significant protection. GuidAge was funded by industry (Ipsen) and still did not find a benefit.

Form and dose studied

One standardised extract (EGb 761 in GuidAge) at one trial amount; tea, raw leaf and seeds were not tested. Standardised dry leaf extract (EGb 761 in GuidAge and many dementia trials; other standardised extracts elsewhere). Tea, raw leaf and seeds were not what these trials tested, and food sources differ from pills.

Who was studied

Adults aged 70 or older, with normal thinking, mild cognitive impairment or memory complaints.

Limits

Results apply to older adults and to these extracts. Younger people were not studied. GuidAge noted that risk was not steady over time.

Why researchers looked

Ginkgo is widely sold for memory, so large trials asked whether taking it for years protects the brain.

Traditional use

Ginkgo leaf is an old remedy in Chinese medicine, but the modern standardised leaf extract used in trials is a different, refined product.

Proposed mechanism Not established

Not established. Ginkgo leaf extract contains flavonoids and terpene lactones (ginkgolides and bilobalide). Lab and animal work suggests many possible actions, but none has been shown to explain a memory effect in people.

A proposed mechanism does not show that the effect happens in people.

Adverse effect profiles were similar to placebo in GEM; see the Safety tab for bleeding cautions.

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Slowing memory and thinking decline with age

Evidence against

In the same US trial, ginkgo did not slow the yearly decline in memory, attention, language, planning or overall thinking scores in people aged 72 to 96, whether or not they had mild cognitive impairment.

1 studiesStandardised dry leaf extract (EGb 761 in GuidAge and many dementia t…

Studies, doses and limits

What the trials found

GEM cognitive analysis (JAMA 2009, 3,069 people, median 6.1 years): yearly memory decline was 0.043 on ginkgo and 0.041 on placebo, with no group difference in any area. Age, sex, education and the APOE e4 gene did not change this.

Results

Ginkgo did not slow normal thinking decline in this large trial.

Effect sizes as reported

No group difference on the Modified Mini-Mental State (P = .71) or ADAS-Cog (P = .97).

Why this rating

A large randomised trial with 6 years of follow-up and a clear null result.

Form and dose studied

Who was studied

Community-dwelling adults aged 72 to 96.

Limits

One trial, one product. It does not test short courses before an exam or in younger people.

Why researchers looked

Many people take ginkgo hoping to keep memory sharp as they get older.

Traditional use

Ginkgo leaf is an old remedy in Chinese medicine, but the modern standardised leaf extract used in trials is a different, refined product.

Proposed mechanism Not established

A proposed mechanism does not show that the effect happens in people.

No extra safety signal in this analysis.

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Memory in healthy adults

Evidence against

Studies in healthy people do not show a memory boost. A pooled analysis of trials found effects close to zero for memory, planning and attention. A six-week trial in healthy adults over 60 also found nothing.

2 studiesStandardised dry leaf extract (EGb 761 in GuidAge and many dementia t…

Studies, doses and limits

What the trials found

Pooled analysis (Human Psychopharmacology 2012): memory d = -0.04 (95% CI -0.17 to 0.07), executive function d = -0.05, attention d = -0.08, in 534 to 1,132 healthy people. Effects did not depend on age, trial length or dose. In JAMA 2002, 230 healthy adults older than 60 took ginkgo or placebo for six weeks: no differences on any test, on self-rated memory, or on a companion's rating.

Results

No measurable memory benefit in healthy adults. This is evidence against the common marketing claim.

Effect sizes as reported

Memory d = -0.04; executive function d = -0.05; attention d = -0.08.

Why this rating

A meta-analysis plus a separate randomised trial, both null.

Form and dose studied

Who was studied

Healthy adults, young and old.

Limits

Trials were mostly short and used different products.

Why researchers looked

Ginkgo is often marketed as a memory booster for healthy people.

Traditional use

Ginkgo leaf is an old remedy in Chinese medicine, but the modern standardised leaf extract used in trials is a different, refined product.

Proposed mechanism Not established

A proposed mechanism does not show that the effect happens in people.

Not applicable.

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Mild cognitive impairment (MCI)

Evidence against

For people with mild cognitive impairment, the 2026 Cochrane review found ginkgo probably has little or no effect on overall status, thinking or daily activities at six months.

1 studiesStandardised dry leaf extract (EGb 761 in GuidAge and many dementia t…

Studies, doses and limits

What the trials found

Cochrane 2026: 12 trials with 1,913 people. At six months, moderate-certainty evidence of little or no effect on global status, ADAS-Cog (MD -0.07, 95% CI -0.67 to 0.51) and daily activities. Serious side effects did not differ from placebo (RR 0.95, 0.82 to 1.09; high certainty).

Results

Probably little or no benefit in MCI, with moderate certainty.

Effect sizes as reported

ADAS-Cog MD -0.07 (-0.67 to 0.51); serious side effects RR 0.95 (0.82 to 1.09).

Why this rating

Moderate-certainty Cochrane evidence, from several trials.

Form and dose studied

Who was studied

Adults with mild cognitive impairment.

Limits

Trials mostly lasted six months.

Why researchers looked

MCI is a step before dementia, and people ask whether ginkgo can slow it.

Traditional use

Ginkgo leaf is an old remedy in Chinese medicine, but the modern standardised leaf extract used in trials is a different, refined product.

Proposed mechanism Not established

A proposed mechanism does not show that the effect happens in people.

No excess of serious side effects was found at up to 12 months in these trials.

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Symptoms in people who already have dementia

Low certainty

For people who already have dementia, the evidence leans slightly positive but is shaky. The 2026 Cochrane review found low-certainty hints of small to moderate help at six months. NCCIH calls the evidence inconsistent.

4 studiesStandardised dry leaf extract (EGb 761 in GuidAge and many dementia t…

Studies, doses and limits

What the trials found

Cochrane 2026: 13 trials with 3,288 people with dementia. At six months, low-certainty evidence of better global status, better scores on a short thinking test (SKT MD -1.86, 95% CI -3.48 to -0.24) and slightly better daily activities, with very large differences between trials (I2 up to 96%). A 2015 meta-analysis of 9 trials of EGb 761 (2,561 people) and a 2025 analysis of 782 people with mild dementia also favoured the extract; the 2025 analysis comes from trials of a branded product and may be manufacturer-linked.

Results

Possible small benefit for symptoms in dementia, but low certainty. Ginkgo is not a proven treatment and does not cure or reverse dementia.

Effect sizes as reported

Cochrane: SKT MD -1.86 (-3.48 to -0.24). 2015 meta-analysis: cognition MD -2.86.

Why this rating

Cochrane rated the evidence low-certainty with large differences between trials; the 2015 and 2025 EGb 761 analyses lean more positive.

Form and dose studied

Standardised dry leaf extract (EGb 761 in GuidAge and many dementia trials; other standardised extracts elsewhere). Tea, raw leaf and seeds were not what these trials tested, and food sources differ from pills. The trials compared different daily amounts; the amounts studied appear in the studies table only and are not advice.

Who was studied

People with a dementia diagnosis, mainly mild to moderate.

Limits

Short trials, many small and at risk of bias (only 4 of 82 trials were at low risk of bias in every area).

Why researchers looked

Several trials tested ginkgo extract as an add-on treatment in people with Alzheimer disease, vascular dementia or mixed dementia.

Traditional use

Ginkgo leaf is an old remedy in Chinese medicine, but the modern standardised leaf extract used in trials is a different, refined product.

Proposed mechanism Not established

A proposed mechanism does not show that the effect happens in people.

People with dementia are often on blood thinners or other medicines. Ask a doctor or pharmacist first.

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Ringing in the ears (tinnitus)

Very low certainty

Ginkgo may make little or no difference to tinnitus, and the evidence is very uncertain. The Cochrane review pooled two trials and found no meaningful change in symptom scores.

1 studiesStandardised dry leaf extract (EGb 761 in GuidAge and many dementia t…

Studies, doses and limits

What the trials found

Cochrane 2022: 12 trials, 1,915 people. Pooled tinnitus severity (2 trials, 85 people) MD -1.35 on a 0 to 100 scale (95% CI -8.26 to 5.55; very low certainty). Little to no difference in bleeding or seizure risk across 4 trials (1,154 people; low certainty).

Results

No clear benefit for tinnitus; the evidence is too weak to say either way.

Effect sizes as reported

Tinnitus Handicap Inventory MD -1.35 (-8.26 to 5.55).

Why this rating

Cochrane graded the evidence low to very low, with high or unclear risk of bias in most trials.

Form and dose studied

Who was studied

Adults and children with tinnitus.

Limits

Small trials, mixed products and methods.

Why researchers looked

Ginkgo has long been used for ringing in the ears.

Traditional use

Ginkgo leaf is an old remedy in Chinese medicine, but the modern standardised leaf extract used in trials is a different, refined product.

Proposed mechanism Not established

A proposed mechanism does not show that the effect happens in people.

No excess bleeding or seizures were seen in the pooled trials, with low certainty.

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Leg pain when walking (intermittent claudication)

Low certainty

In people with leg pain from narrowed arteries, ginkgo added a small, not statistically significant amount of walking distance. The Cochrane authors say there is no evidence of a clinically significant benefit.

1 studiesStandardised dry leaf extract (EGb 761 in GuidAge and many dementia t…

Studies, doses and limits

What the trials found

Cochrane 2013: 14 trials, 739 people. In 11 trials (477 people) walking distance rose by 3.57 kcal of effort (about 64.5 metres on a flat treadmill; 95% CI -0.10 to 7.23 kcal, P = 0.06). The authors say missing negative trials probably inflated the result.

Results

Little or no useful benefit for walking distance.

Effect sizes as reported

+3.57 kcal (about 64.5 m); CI -0.10 to 7.23 kcal.

Why this rating

Cochrane meta-analysis, but publication bias likely and the result was not significant.

Form and dose studied

Who was studied

Adults with intermittent claudication.

Limits

The Cochrane review dates from 2013.

Why researchers looked

Ginkgo is thought to widen blood vessels, so it was tested for walking distance in artery disease.

Traditional use

Ginkgo leaf is an old remedy in Chinese medicine, but the modern standardised leaf extract used in trials is a different, refined product.

Proposed mechanism Not established

A proposed mechanism does not show that the effect happens in people.

Bleeding cautions on the Safety tab matter for people with artery disease who take blood thinners.

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Preventing altitude sickness

Mixed findings

Results are mixed. Pooled trials hint that ginkgo might lower altitude sickness risk, but the main result was not statistically significant and the trials disagreed with each other.

1 studiesStandardised dry leaf extract (EGb 761 in GuidAge and many dementia t…

Studies, doses and limits

What the trials found

BMJ Open 2018: 7 study groups, 451 people. RR 0.68 (95% CI 0.45 to 1.04, P = 0.08; I2 58.7%). The pooled risk difference was -25% (-45% to -6%). The authors conclude there are not enough data to show an effect.

Results

Possible trend, unproven.

Effect sizes as reported

RR 0.68 (0.45 to 1.04).

Why this rating

Few small trials with conflicting results and substantial differences between them.

Form and dose studied

Who was studied

People climbing to altitude.

Limits

Different altitudes and starting times.

Why researchers looked

Ginkgo is thought to improve blood flow, so it was tested before climbs.

Traditional use

Ginkgo leaf is an old remedy in Chinese medicine, but the modern standardised leaf extract used in trials is a different, refined product.

Proposed mechanism Not established

A proposed mechanism does not show that the effect happens in people.

Not a replacement for proper pacing of ascent; ask a doctor about altitude medicines.

²⁵

Connections to the rest of health

How Ginkgo biloba connects to the rest of our health knowledge graph. Every link says what kind of connection it is. A safety link (for example to the liver) is a warning, not a benefit. A study that merely mentions a topic never creates a benefit link.

Explore every connection: goals, body systems, organs, symptoms, genes

Kind of connection Connected to Search

A. Wellness goals

Connected to	Evidence status	Context	Studies
Brain Health	Evidence against	Preventing dementia in older adults: Two large, long trials in older adults found that ginkgo extract did not lower the chance of getting dementia or Alzheimer disease. The US trial (3,069 people aged 75 or older, median 6.1 years) found slightly more dementia on ginkgo than on placebo, though not a clear difference. Mild cognitive impairment (MCI): For people with mild cognitive impairment, the 2026 Cochrane review found ginkgo probably has little or no effect on overall status, thinking or daily activities at six months.	^{1 26 30 27}
Healthy Aging	Evidence against	Preventing dementia in older adults: Two large, long trials in older adults found that ginkgo extract did not lower the chance of getting dementia or Alzheimer disease. The US trial (3,069 people aged 75 or older, median 6.1 years) found slightly more dementia on ginkgo than on placebo, though not a clear difference. Slowing memory and thinking decline with age: In the same US trial, ginkgo did not slow the yearly decline in memory, attention, language, planning or overall thinking scores in people aged 72 to 96, whether or not they had mild cognitive impairment.	^{1 26 30 20}
Memory Support	Evidence against	Preventing dementia in older adults: Two large, long trials in older adults found that ginkgo extract did not lower the chance of getting dementia or Alzheimer disease. The US trial (3,069 people aged 75 or older, median 6.1 years) found slightly more dementia on ginkgo than on placebo, though not a clear difference. Slowing memory and thinking decline with age: In the same US trial, ginkgo did not slow the yearly decline in memory, attention, language, planning or overall thinking scores in people aged 72 to 96, whether or not they had mild cognitive impairment.	^{1 26 30 20 11 21 27}
Cognitive Performance	Evidence against	Slowing memory and thinking decline with age: In the same US trial, ginkgo did not slow the yearly decline in memory, attention, language, planning or overall thinking scores in people aged 72 to 96, whether or not they had mild cognitive impairment.	²⁰
Better Focus	Evidence against	Memory in healthy adults: Studies in healthy people do not show a memory boost. A pooled analysis of trials found effects close to zero for memory, planning and attention. A six-week trial in healthy adults over 60 also found nothing.	^{11 21}
Mental Clarity	Evidence against	Memory in healthy adults: Studies in healthy people do not show a memory boost. A pooled analysis of trials found effects close to zero for memory, planning and attention. A six-week trial in healthy adults over 60 also found nothing.	^{11 21}
Memory Support	Low certainty	Symptoms in people who already have dementia: For people who already have dementia, the evidence leans slightly positive but is shaky. The 2026 Cochrane review found low-certainty hints of small to moderate help at six months. NCCIH calls the evidence inconsistent.	^{27 24 18 30}
Brain Health	Low certainty	Symptoms in people who already have dementia: For people who already have dementia, the evidence leans slightly positive but is shaky. The 2026 Cochrane review found low-certainty hints of small to moderate help at six months. NCCIH calls the evidence inconsistent.	^{27 24 18 30}
Healthy Aging	Low certainty	Symptoms in people who already have dementia: For people who already have dementia, the evidence leans slightly positive but is shaky. The 2026 Cochrane review found low-certainty hints of small to moderate help at six months. NCCIH calls the evidence inconsistent.	^{27 24 18 30}
Calm Relaxation	Very low certainty	Ringing in the ears (tinnitus): Ginkgo may make little or no difference to tinnitus, and the evidence is very uncertain. The Cochrane review pooled two trials and found no meaningful change in symptom scores.	¹⁹
Heart Health	Low certainty	Leg pain when walking (intermittent claudication): In people with leg pain from narrowed arteries, ginkgo added a small, not statistically significant amount of walking distance. The Cochrane authors say there is no evidence of a clinically significant benefit.	¹⁶
Physical Stamina	Mixed findings	Preventing altitude sickness: Results are mixed. Pooled trials hint that ginkgo might lower altitude sickness risk, but the main result was not statistically significant and the trials disagreed with each other.	²⁵

B. Body systems

Connected to	Kind of connection	Evidence status	Context	Studies
Nervous System	Biological association	Evidence against	Studied for: Preventing dementia in older adults Studied for: Slowing memory and thinking decline with age	^{1 26 30 20 11 21 27 24 18 19 16 25}

I. Biomarkers

Connected to	Kind of connection	Evidence status	Context	Studies
New cases of dementia	Biological association	Evidence against	Measured in trials: no lower on ginkgo. A lab change is not the same as a health benefit.	^{1 26}
Yearly decline in memory scores	Biological association	Evidence against	Measured in trials: no slower on ginkgo. A lab change is not the same as a health benefit.	²⁰
Memory test scores in healthy adults	Biological association	Evidence against	Measured in trials: no change. A lab change is not the same as a health benefit.	^{11 21}
Short Cognitive Performance Test (SKT) in dementia	Biological association	Low certainty	Measured in trials: lower (better) in some trials. A lab change is not the same as a health benefit.	²⁷
Tinnitus Handicap Inventory score	Biological association	Very low certainty	Measured in trials: little or no change. A lab change is not the same as a health benefit.	¹⁹
Walking distance	Biological association	Low certainty	Measured in trials: slightly longer (not significant). A lab change is not the same as a health benefit.	¹⁶
Chance of acute mountain sickness	Biological association	Mixed findings	Measured in trials: lower trend (not significant). A lab change is not the same as a health benefit.	²⁵

K. Biological pathways

Connected to	Kind of connection	Evidence status	Context	Studies
Vitamin B6	Preliminary mechanism	Human	The toxin in ginkgo seeds works against vitamin B6.	^{7 5}

L. Active compounds

Connected to	Kind of connection	Evidence status	Context	Studies
Ginkgolides A, B, C and J, and bilobalide (terpene lactones)	Biological association	Human	A chemistry review says these are the most unusual components of the extracts and are believed to explain part of the effect on nerve signalling. A human study found ginkgolide A and B reach higher blood levels than C and J, and that changes in the blood form lowered their lab activity against platelet-activating factor. Preparation or compound: Leaf	^{23 12 15}
Flavonol glycosides (flavonoids)	Biological association	In vitro	No clinical effect of the flavonoids alone was read. Preparation or compound: Leaf	¹⁵
Ginkgolic acid	Biological association	Unknown	Not researched here beyond content.	¹⁵

Each connection is stored with the ingredient, the connected record, the kind of connection, the evidence status, the supporting studies, the preparation or compound involved, and a review date (last reviewed October 26, 2026).

Evidence at a glance: what the research found for 8 outcomes

2Low certainty

1Very low certainty

1Mixed findings

4Evidence against

Each outcome below is one thing researchers measured. Certainty is how far the evidence can be trusted, not how well it works. The full studies are on the next tab.

Preventing dementia in older adults 3 studies Evidence against Slowing memory and thinking decline with age 1 study Evidence against Memory in healthy adults 2 studies Evidence against Mild cognitive impairment (MCI) 1 study Evidence against Symptoms in people who already have dementia 4 studies Low certainty Ringing in the ears (tinnitus) 1 study Very low certainty Leg pain when walking (intermittent claudication) 1 study Low certainty Preventing altitude sickness 1 study Mixed findings

The evidence

The research centre for Ginkgo biloba. Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.

Evidence by outcome

Bars show how many studies we found for each outcome, not how well it works. People are added up across trials only (reviews are not added, to avoid double counting).

How we rate evidence

High certainty

Several well-run trials or reviews agree; further research is unlikely to change the picture much.

Moderate certainty

Good trials point the same way, but some doubt remains.

Low certainty

Small, short or inconsistent trials. The finding could change with better research.

Very low certainty

Very little or very weak human data. Treat as a possibility only.

Mixed findings

Trials or reviews disagree with each other.

Not enough evidence

Not enough human research to say either way.

Evidence against

Good research found no benefit, or found harm.

We take the reviewers' own risk-of-bias and GRADE statements where they exist, and otherwise judge from study size, design, consistency, directness and whether a product matches what is sold. Many publications do not make evidence high. Method note: We started from our existing ginkgo herb profile, then re-read each PubMed abstract used here and a summary of the NCCIH page and the GBIF record. Only abstracts were read for studies. The EMA monograph was not read.

Study library: every study we checked 30

Design Research type Year from Search

Study	Design	People	Product, dose, length	Result
DeKosky 2008 Ginkgo biloba for prevention of dementia: a randomized controlled trial. JAMA · PMID 19017911 · DOI	Randomised controlled trial	3069 Community volunteers aged 75 or older: 2,587 with normal thinking and 482 with mild cognitive impairment (MCI); median follow-up 6.1 years	Ginkgo biloba leaf extract (standardised) Dry leaf extract (capsule or tablet) 120 mg twice a day (studied in the trial) Median 6.1 years · vs Placebo	Ginkgo did not lower new dementia. 523 people developed dementia (277 on ginkgo, 246 on placebo). Rates were 3.3 versus 2.9 per 100 person-years. Side effect profiles were similar. It also did not slow progression from MCI to dementia. All-cause dementia HR 1.12; Alzheimer disease HR 1.16; MCI to dementia HR 1.13 (95% CI 0.94 to 1.33 (all-cause); 0.97 to 1.39 (Alzheimer); 0.85 to 1.50 (MCI)) Methods, limits and funding Outcomes: New dementia (all causes) and Alzheimer disease Limitations: One extract, one dose, volunteers aged 75 or older; results may not apply to younger people or other products. Funding and conflicts: PubMed lists US National Institutes of Health extramural support. Funding is not stated in the abstract text. Registration: NCT00010803 Read: abstract
Dugoua 2006 Safety and efficacy of ginkgo (Ginkgo biloba) during pregnancy and lactation. Can J Clin Pharmacol · PMID 17085776	Review	Review of the literature on ginkgo in pregnancy and breastfeeding	Ginkgo leaf Leaf	The authors found only very weak evidence from animal and test-tube studies that ginkgo has antiplatelet activity, which may prolong bleeding around labour. Safety during breastfeeding is unknown. They advise caution in pregnancy, especially around labour. Not applicable (Not applicable) Methods, limits and funding Outcomes: Safety in pregnancy and lactation Limitations: No human trials in pregnancy were found; conclusions rest on weak evidence and expert opinion. 2006 review. Funding and conflicts: Funding not stated in the abstract. Read: abstract
Gong 2008 Phylogeography of a living fossil: pleistocene glaciations forced Ginkgo biloba L. (Ginkgoaceae) into two refuge areas in China with limited subsequent postglacial expansion. Mol Phylogenet Evol · PMID 18554931 · DOI	Plant genetics study plant	Populations of Ginkgo biloba trees in China	Ginkgo biloba (tree) Whole tree	Says Ginkgo biloba is native to China, is the only surviving species of its genus, and was spread by people to temperate regions less than 300 years ago. It suggests two ice-age refuge areas in south-west and eastern China. Not applicable (Not applicable) Methods, limits and funding Outcomes: Where the species survived and how it spread Limitations: A genetics paper, not a medical study. Funding and conflicts: Not stated. Read: abstract
Harms 2006 Ginkgo biloba use in nursing home elderly with epilepsy or seizure disorder. Epilepsia · PMID 16499756 · DOI	Observational prevalence study	68403 US nursing home residents (68,403 in 557 facilities) over one year, including people with epilepsy or seizure disorder	Ginkgo (prescribed as an herb) 1 year	Ginkgo was the most prescribed herb (162 orders). It was prescribed to 61.9% of herb-treated residents with seizure disorders and 58.0% of those without, so it was not avoided in people with epilepsy. The authors say ginkgo can both cause and block seizures and worry that unstandardised products may contain seed material linked to seizures. Ginkgo ordered 162 times of 307 herb orders (0.41% of residents used any herb) (Not applicable) Methods, limits and funding Outcomes: How often ginkgo was prescribed to residents with and without epilepsy Limitations: Describes prescribing, not harm. It does not show that ginkgo caused any seizure. Funding and conflicts: Funding not stated in the abstract (PubMed lists US NIH support). Read: abstract
Jang 2015 Ginkgotoxin Induced Seizure Caused by Vitamin B6 Deficiency. J Epilepsy Res · PMID 26819944 · DOI	Case report	1 One 51-year-old woman who ate large amounts of ginkgo nuts	Ginkgo nuts (not leaf extract) Nuts eaten as food Large amounts (not measured) Single episode	She had a generalised seizure and confusion; her blood vitamin B6 was low. She recovered fully with supportive care and vitamin B6 treatment and had no more seizures. Single case (Not applicable) Methods, limits and funding Outcomes: Seizure and confusion Limitations: One case; nuts, not supplements. Funding and conflicts: Not stated. Read: abstract
Jiang 2005 Effect of ginkgo and ginger on the pharmacokinetics and pharmacodynamics of warfarin in healthy subjects. Br J Clin Pharmacol · PMID 15801937 · DOI	Randomised crossover trial	12 12 healthy men in a three-way crossover	Ginkgo and ginger herbal products, with a single dose of warfarin Herbal products of known quality Recommended product amounts for 7 days before and 7 days after a single warfarin dose 2 weeks per period · vs Warfarin alone	Ginkgo alone did not change INR or platelet clumping, and did not change how warfarin was handled or how strongly it worked. INR area-under-curve ratio with ginkgo 0.93; S-warfarin clearance ratio 1.05 (90% CI 0.81 to 1.05 (INR); 0.98 to 1.21 (S-warfarin)) Methods, limits and funding Outcomes: INR, platelet clumping, warfarin blood levels and clearance Limitations: Only 12 healthy men and a single warfarin dose. It cannot show what happens in long-term warfarin patients. Funding and conflicts: Funding not stated in the abstract. Read: abstract
Kajiyama 2002 Ginkgo seed poisoning. Pediatrics · PMID 11826216 · DOI	Case report	1 One 2-year-old girl who ate a large quantity of ginkgo seeds	Ginkgo seeds (not leaf extract) Raw seeds eaten as food A large quantity (not measured) Single episode	She vomited and had diarrhoea 7 hours after eating the seeds and a seizure at 9 hours. Blood levels of 4-methoxypyridoxine, a vitamin B6 blocker in the seeds, were high. The authors say prompt treatment with the active form of vitamin B6 may have prevented more seizures. Single case (Not applicable) Methods, limits and funding Outcomes: Vomiting, diarrhoea and seizure Limitations: One child; seeds, not supplements. Funding and conflicts: Not stated. Read: abstract
Kellermann 2011 Is there a risk of bleeding associated with standardized Ginkgo biloba extract therapy? A systematic review and meta-analysis. Pharmacotherapy · PMID 21923430 · DOI	Systematic review meta analysis	1985 18 randomised trials, 1,985 adults (87% had dementia, peripheral artery disease or diabetes; 13% healthy)	Standardised ginkgo leaf extracts Extract Varied; one subgroup used 240 mg a day or more Varied · vs Placebo	No effect on platelet clumping, fibrinogen or prothrombin time. A small lowering of aPTT (a clotting time) was found in some subgroups but was judged not clinically relevant. Blood thickness (viscosity) fell. The authors concluded these measures did not point to a higher bleeding risk. Platelet aggregation WMD -0.35%; aPTT -0.42 s; PT SMD 0.00 (Platelet aggregation -15.16 to 14.46%; aPTT -0.97 to 0.12 s; PT -0.09 to 0.09) Methods, limits and funding Outcomes: Clotting and platelet measures linked to bleeding risk Limitations: Looked at lab clotting markers, not actual bleeding events, and trials were not designed to detect rare bleeds. Funding and conflicts: Funding not stated in the abstract (PubMed lists non-US government research support). Read: abstract
Kloft 2021 EGb 761(®) Does Not Affect Blood Coagulation and Bleeding Time in Patients with Probable Alzheimer's Dementia-Secondary Analysis of a Randomized, Double-Blind Placebo-Controlled Trial. Healthcare (Basel) · PMID 34946404 · DOI	Secondary analysis of rct	513 People with probable Alzheimer dementia in a randomised placebo-controlled trial; 68 on placebo and 105 on ginkgo also took aspirin; 9 per group took warfarin	EGb 761 standardised ginkgo leaf extract Dry leaf extract (capsule or tablet) 120 mg or 240 mg a day (studied in the trial) 26 weeks · vs Placebo	No relevant change in clotting measures or bleeding time. Bleeding-related side effects were similar across groups. The authors found no sign of interaction with aspirin or warfarin, though only 9 people per group took warfarin. Changes under 1 unit for prothrombin time and bleeding time; under 0.1 for INR (Not given in the abstract) Methods, limits and funding Outcomes: Prothrombin time, aPTT, INR, bleeding time, bleeding-related side effects Limitations: Secondary analysis; very few people on warfarin. Funding and conflicts: Funding and author ties are not stated in the abstract. EGb 761 is a branded extract, so a manufacturer link is possible and not confirmed. Read: abstract
Kupiec 2005 Fatal seizures due to potential herb-drug interactions with Ginkgo biloba. J Anal Toxicol · PMID 16419414 · DOI	Case report	1 One 55-year-old man who died of a seizure while using anticonvulsant medicines and many supplements, including ginkgo	Ginkgo biloba (among many supplements)	Blood levels of both seizure medicines were below the treatment range. The authors suggest ginkgo may have lowered them by speeding up their breakdown, which is a possible explanation, not a proven cause. Single case (Not applicable) Methods, limits and funding Outcomes: Fatal seizure with low anticonvulsant levels Limitations: He took many supplements; ginkgo cannot be singled out. The authors' explanation is a hypothesis. Funding and conflicts: Not stated. Read: abstract
Laws 2012 Is Ginkgo biloba a cognitive enhancer in healthy individuals? A meta-analysis. Hum Psychopharmacol · PMID 23001963 · DOI	Meta-analysis	1132 Healthy adults in randomised trials: memory (13 trials, 1,132 people), executive function (7 trials, 534), attention (8 trials, 910)	Ginkgo biloba (various products) Leaf extracts Varied Varied · vs Placebo	Effects were close to zero for memory, executive function and attention. They were not related to age, trial length or dose. Memory d = -0.04; executive function d = -0.05; attention d = -0.08 (Memory -0.17 to 0.07; executive function -0.17 to 0.05; attention -0.21 to 0.02) Methods, limits and funding Outcomes: Memory, executive function and attention test scores Limitations: Mixes different products and short trials. A meta-analysis of published trials may miss unpublished ones. Funding and conflicts: Funding not stated in the abstract. Read: abstract
Liu 2018 Human pharmacokinetics of ginkgo terpene lactones and impact of carboxylation in blood on their platelet-activating factor antagonistic activity. Acta Pharmacol Sin · PMID 30054600 · DOI	Human pharmacokinetic study	Human volunteers given a ginkgo tablet by mouth or an injectable ginkgo product, plus lab tests	Ginkgo terpene lactones (ginkgolides A, B, C, J and bilobalide) Tablet or injection Single exposure	Ginkgolides A and B and bilobalide reached higher blood levels than ginkgolides C and J after the tablet. Half-lives were about 4 to 13 hours. The body clears ginkgolides mainly through the kidneys. In the blood the compounds partly change form, and that change lowered their lab activity against platelet-activating factor. Half-life of ginkgolides A, B, C 6 to 13 hours after tablet; bilobalide about 5 hours (Not applicable) Methods, limits and funding Outcomes: Blood levels, half-life and platelet-activating factor blocking in the lab Limitations: Chinese-market products (a tablet and an injectable), which may differ from other products; the platelet part is a test-tube measurement, not a clinical result. Funding and conflicts: Funding not stated in the abstract. Read: abstract
Mai 2025 Impact of Ginkgo biloba drug interactions on bleeding risk and coagulation profiles: A comprehensive analysis. PLoS One · PMID 40198642 · DOI	Observational record study	2647 Hospital records in Hai Phong, Vietnam, 2022 to 2023: 2,647 ginkgo prescriptions; 747 patients checked for bleeding	Ginkgo biloba extract prescribed alone or with other medicines Prescription extract	342 prescriptions (12.94%) had a drug interaction, mostly with antiplatelet drugs, anticoagulants and anti-inflammatory painkillers; clopidogrel and aspirin were top at 2.61% each. 31 of 747 patients (4.15%) had bleeding symptoms. Ginkgo interactions were linked to bleeding risk and abnormal clotting tests. Interactions with anticoagulants such as direct oral anticoagulants and acenocoumarol were not statistically significant. Interaction and bleeding risk OR 1.08; abnormal coagulation OR 1.49 (p < 0.001 for both) Methods, limits and funding Outcomes: Drug interactions, bleeding symptoms, clotting tests Limitations: Retrospective single-hospital record review; cannot prove cause. Funding and conflicts: Funding not stated in the abstract. Read: abstract
Miller 2002 Possible subdural hematoma associated with Ginkgo biloba. J Herb Pharmacother · PMID 15277097	Case report	1 One 78-year-old man who fell and then developed a chronic subdural hematoma (bleeding around the brain)	Ginkgo biloba 50 mg three times a day (as reported)	His only other medicine was lisinopril. The authors believe ginkgo either caused or contributed to the bleed. Single case (Not applicable) Methods, limits and funding Outcomes: Bleeding around the brain Limitations: One case after a fall; cause cannot be proved. Funding and conflicts: Not stated. Read: abstract
National Toxicology Program 2013 Toxicology and carcinogenesis studies of Ginkgo biloba extract (CAS No. 90045-36-6) in F344/N rats and B6C3F1/N mice (Gavage studies). Natl Toxicol Program Tech Rep Ser · PMID 23652021	Animal toxicology animal	Rats and mice dosed by stomach tube for 3 months and 2 years (NTP report)	Ginkgo biloba leaf extract, 31.2% flavonol glycosides, 15.4% terpene lactones, 10.45 ppm ginkgolic acid Extract in corn oil Many dose levels, per kilogram of body weight in animals 14 weeks and 2 years · vs Vehicle (corn oil)	In animals the extract enlarged livers with liver cell changes, damaged the lining of the nose, and affected the thyroid. Tumours increased in some groups: thyroid follicular cell adenoma in rats, and liver adenoma in some male rats. This is animal evidence at high doses and does not show the same in people. Not applicable (Not applicable) Methods, limits and funding Outcomes: Organ damage, tumours and genetic toxicity Limitations: Animal work with gavage doses far above supplement use; relevance to people is unknown. Funding and conflicts: US National Toxicology Program (government). Read: abstract
Nicolaï 2013 Ginkgo biloba for intermittent claudication. Cochrane Database Syst Rev · PMID 23744597 · DOI	Systematic review meta analysis	739 14 randomised trials (739 people) in intermittent claudication (leg pain when walking); 11 trials (477 people) measured absolute claudication distance	Ginkgo biloba leaf extract Extract Varied Varied · vs Placebo	Walking distance rose by an average of 3.57 kilocalories of effort, about 64.5 metres on a flat treadmill, and the result was not statistically significant. The authors say missing negative trials probably inflated it, and conclude there is no evidence of a clinically significant benefit. Absolute claudication distance +3.57 kcal (about 64.5 m) (-0.10 to 7.23 kcal (P = 0.06)) Methods, limits and funding Outcomes: Walking distance on a treadmill Limitations: Publication bias likely inflated the effect. Funding and conflicts: Cochrane review; funding of individual trials not stated in the abstract. Read: abstract
Orhan 2024 Estimating the extent of adulteration of the popular herbs black cohosh, echinacea, elder berry, ginkgo, and turmeric - its challenges and limitations. Nat Prod Rep · PMID 39108221 · DOI	Review	533 78 publications covering 2,995 samples of five popular herbs; 533 were ginkgo leaf samples	Ginkgo leaf products on the market Dietary supplements and licensed herbal medicines	Ginkgo leaf had the highest rate of adulteration or mislabelling of the five herbs: 56.7% of 533 samples. Licensed or registered herbal medicines had a lower risk than dietary supplements. The authors warn the data have significant limits. 56.7% of ginkgo samples adulterated or mislabelled (Not given in the abstract) Methods, limits and funding Outcomes: Share of products adulterated or mislabelled Limitations: Based on published tests of varied quality; the authors say the figures cannot be applied to other herbs and the market changes quickly. Funding and conflicts: Funding not stated in the abstract; PubMed lists non-US government research support. Read: abstract
Riepe 2025 Ginkgo biloba extract EGb 761 is safe and effective in the treatment of mild dementia - a meta-analysis of patient subgroups in randomised controlled trials. World J Biol Psychiatry · PMID 39895346 · DOI	Meta-analysis	782 Four randomised placebo-controlled trials; only the 782 patients with mild dementia (SKT score 9 to 15) were pooled	EGb 761 standardised ginkgo leaf extract Dry leaf extract (capsule or tablet) 240 mg a day (studied in the trials) Mostly about 24 weeks · vs Placebo	In this subgroup the extract beat placebo on thinking (P = 0.04), global assessment (P = 0.01), daily activities (P = 0.01) and quality of life (P = 0.02). Side effects were alike in both groups. Standardised effects reported as medium to large (Not given in the abstract) Methods, limits and funding Outcomes: Thinking, global assessment, daily activities, quality of life, side effects Limitations: A subgroup analysis of trials of one product, not a fresh trial. Funding is not stated in the abstract. EGb 761 is a branded extract, so treat the result as possibly manufacturer-linked. Funding and conflicts: Funding not stated in the abstract; industry link possible and not confirmed. Read: abstract
Sereda 2022 Ginkgo biloba for tinnitus. Cochrane Database Syst Rev · PMID 36383762 · DOI	Systematic review meta analysis	1915 12 randomised trials (1,915 people) of adults and children with tinnitus	Ginkgo biloba (various products) Various Varied Mostly 3 to 6 months · vs Placebo (11 trials); hearing aids alone (1 trial)	Ginkgo may make little or no difference to tinnitus severity, but the evidence is very uncertain. Four trials with 1,154 people suggested little or no difference in bleeding or seizures, with no serious side effects in either group. Tinnitus severity MD -1.35 on a 0 to 100 scale (2 trials, 85 people) (-8.26 to 5.55) Methods, limits and funding Outcomes: Tinnitus severity (Tinnitus Handicap Inventory), loudness, quality of life, bleeding and seizures Limitations: Risk of bias was high or unclear in most trials; certainty was low to very low. Funding and conflicts: Cochrane review; funding of individual trials not stated in the abstract. Read: abstract
Snitz 2009 Ginkgo biloba for preventing cognitive decline in older adults: a randomized trial. JAMA · PMID 20040554 · DOI	Randomised controlled trial	3069 Community-dwelling adults aged 72 to 96 (same GEM trial as above); median follow-up 6.1 years	Ginkgo biloba leaf extract (standardised) Dry leaf extract (capsule or tablet) 120 mg twice a day (studied in the trial) Median 6.1 years · vs Placebo	Ginkgo did not slow thinking decline in any area, including memory (yearly decline 0.043 versus 0.041 z-score units). It made no difference in people with normal thinking or with MCI, and age, sex, education or the APOE e4 gene did not change this. Memory decline 0.043 (ginkgo) vs 0.041 (placebo) z-score units per year; no group differences on 3MSE (P = .71) or ADAS-Cog (P = .97) (Memory: 0.034 to 0.051 (ginkgo) and 0.032 to 0.050 (placebo)) Methods, limits and funding Outcomes: Yearly change in memory, attention, visual-spatial skill, language, executive function and two global tests (3MSE, ADAS-Cog) Limitations: Same single extract and dose as the dementia paper; not a test of short-term effects. Funding and conflicts: PubMed lists US National Institutes of Health extramural support. Funding is not stated in the abstract text. Registration: NCT00010803 Read: abstract
Solomon 2002 Ginkgo for memory enhancement: a randomized controlled trial. JAMA · PMID 12186600 · DOI	Randomised controlled trial	230 Healthy community-dwelling adults older than 60 (98 men, 132 women) with Mini-Mental State scores above 26	Ginkgo (over-the-counter product) Oral product 40 mg three times a day (studied in the trial) 6 weeks · vs Matching placebo	No significant difference on any test, on self-rated memory, or on the companion's rating. 203 of 230 people (88%) finished. No significant differences on any outcome (Not given in the abstract) Methods, limits and funding Outcomes: Learning, memory, attention, naming and verbal fluency tests; self-rated memory; a companion's rating of change Limitations: Six weeks only, in healthy older adults. Funding and conflicts: Funding is not stated in the abstract; PubMed lists US public health service support. Read: abstract
Stoddard 2015 Ginkgo and Warfarin Interaction in a Large Veterans Administration Population. AMIA Annu Symp Proc · PMID 26958257	Observational record study	Patients in a large US Veterans Administration records database who were on warfarin, with ginkgo use found by text-mining notes	Ginkgo (use found in medical notes) together with warfarin · vs Warfarin users without ginkgo	Taking ginkgo with warfarin was linked to a higher risk of a bleeding event. Bleeding hazard ratio 1.38 (95% CI 1.20 to 1.58 (p < .001)) Methods, limits and funding Outcomes: Bleeding adverse events Limitations: Observational: it cannot show ginkgo caused the bleeding, and ginkgo use was inferred from free-text notes. Sample size is not given in the abstract. Funding and conflicts: Funding not stated in the abstract. Read: abstract
Strømgaard 2004 Chemistry and biology of terpene trilactones from Ginkgo biloba. Angew Chem Int Ed Engl · PMID 15038029 · DOI	Review mixed	Chemistry review of ginkgo terpene trilactones	Ginkgo terpene trilactones (ginkgolides and bilobalide) Leaf extract	Describes the ginkgolides and bilobalide as the most unusual components of leaf extracts and says they are believed to account for part of the extracts' effects on nerve signalling. Not applicable (Not applicable) Methods, limits and funding Outcomes: Chemistry and biology of the leaf compounds Limitations: A 2004 chemistry review; not a clinical study. Funding and conflicts: Not stated. Read: abstract
Tan 2015 Efficacy and adverse effects of ginkgo biloba for cognitive impairment and dementia: a systematic review and meta-analysis. J Alzheimers Dis · PMID 25114079 · DOI	Systematic review meta analysis	2561 9 randomised trials of 22 to 26 weeks in people with cognitive impairment or dementia	EGb 761 standardised ginkgo leaf extract Dry leaf extract (capsule or tablet) Trials compared 120 and 240 mg a day; the abstract links most benefit to the higher dose 22 to 26 weeks · vs Placebo	Pooled results favoured the extract on thinking, daily activities and global impression, mostly at the higher daily amount tested, with no important safety concern. Cognition weighted mean difference -2.86; daily activities SMD -0.36; global impression Peto OR 1.88 (Cognition -3.18 to -2.54; daily activities -0.44 to -0.28; global impression 1.54 to 2.29) Methods, limits and funding Outcomes: Thinking scores, daily activities, clinician's global impression, side effects Limitations: Only one product (EGb 761), short trials. The 2026 Cochrane review with more trials rated the dementia evidence low-certainty. Funding and conflicts: Funding not stated in the abstract. Read: abstract
Tsai 2018 Ginkgo biloba extract for prevention of acute mountain sickness: a systematic review and meta-analysis of randomised controlled trials. BMJ Open · PMID 30121603 · DOI	Systematic review meta analysis	451 Six articles (seven study groups, 451 people) who climbed to altitude	Ginkgo biloba extract Extract Varied Started before ascent; varied · vs Placebo	Overall there was a trend toward fewer cases that was not statistically significant. Results differed a lot between trials. The authors say there are not enough data to show an effect. RR 0.68 for acute mountain sickness; absolute risk difference -25% (RR 0.45 to 1.04 (P = 0.08); risk difference -45% to -6% (P = 0.011); I2 58.7%) Methods, limits and funding Outcomes: Risk of acute mountain sickness Limitations: Few and small trials, conflicting results. Funding and conflicts: Funding not stated in the abstract. Read: abstract
Vellas 2012 Long-term use of standardised Ginkgo biloba extract for the prevention of Alzheimer's disease (GuidAge): a randomised placebo-controlled trial. Lancet Neurol · PMID 22959217 · DOI	Randomised controlled trial	2854 Adults aged 70 or older in France who told their doctor about memory complaints; followed for 5 years	EGb 761 standardised ginkgo leaf extract Dry leaf extract (capsule or tablet) 120 mg twice a day (studied in the trial) 5 years · vs Matched placebo	61 people on ginkgo and 73 on placebo were diagnosed with probable Alzheimer disease, which was not a significant difference. Deaths, strokes and other bleeding or heart events did not differ between groups. Alzheimer HR 0.84; stroke risk ratio 1.12 (Alzheimer HR 95% CI 0.60 to 1.18 (P = 0.306); stroke 0.77 to 1.63) Methods, limits and funding Outcomes: Conversion to probable Alzheimer disease; deaths, strokes and bleeding or heart events Limitations: Risk was not the same over time, which makes a single hazard ratio harder to read. Funding and conflicts: Funded by Ipsen, a pharmaceutical company. Industry-funded. Registration: NCT00276510 Read: abstract
Wieland 2026 Ginkgo biloba for cognitive impairment and dementia. Cochrane Database Syst Rev · PMID 41641880 · DOI	Systematic review meta analysis	10613 82 randomised trials (10,613 people; 72 trials with 9,783 people gave usable data): subjective memory complaints, MCI, dementia and multiple sclerosis	Ginkgo biloba (mainly leaf extracts) Mixed extracts Varied between trials Mostly 3 to 6 months; some to 12 months · vs Placebo, usual treatment or other treatments	In MCI (12 trials, 1,913 people) ginkgo probably has little or no effect at six months on global status, thinking or daily activities (moderate certainty). In dementia (13 trials, 3,288 people) low-certainty evidence suggests small to moderate benefits at six months, with very large differences between trials. In people with only subjective memory complaints it is uncertain whether it does anything (very low certainty). Serious side effects did not differ from placebo in MCI (high certainty) or dementia (low certainty). MCI: ADAS-Cog MD -0.07; dementia thinking test (SKT) MD -1.86; serious side effects in MCI RR 0.95 (MCI ADAS-Cog -0.67 to 0.51; dementia SKT -3.48 to -0.24 (I2 96%); serious side effects MCI 0.82 to 1.09) Methods, limits and funding Outcomes: Global status, thinking, daily activities, side effects and serious side effects Limitations: Only 4 of 82 trials were at low risk of bias in every area. Dementia results rest on low-certainty evidence with very large differences between trials (I2 up to 96%). Funding and conflicts: Cochrane review; funding of the individual trials varies and is not stated in the abstract. Read: abstract
Zadoyan 2012 Effect of Ginkgo biloba special extract EGb 761® on human cytochrome P450 activity: a cocktail interaction study in healthy volunteers. Eur J Clin Pharmacol · PMID 22189672 · DOI	Randomised crossover trial	18 18 healthy men and women	EGb 761 standardised ginkgo leaf extract Dry leaf extract (capsule or tablet) 120 mg twice a day or 240 mg once a day (studied in the trial) 8 days per treatment · vs Placebo	No relevant effect on any of the five enzymes. Two ratios slightly crossed the limit and the authors attributed that to normal person-to-person variation. Ratios close to 1 for all enzymes (CYP2C19 (120 mg twice a day) 0.681 to 1.122; CYP2D6 (240 mg once a day) 0.667 to 1.281) Methods, limits and funding Outcomes: Activity of five liver enzymes (CYP1A2, 2C9, 2C19, 2D6, 3A) measured with a test-drug cocktail Limitations: Healthy volunteers, short treatment; does not cover every medicine. Funding and conflicts: Funding not stated in the abstract; EGb 761 is a manufacturer-linked product. Read: abstract
s-gbif-ginkgo-biloba GBIF Backbone Taxonomy: Ginkgo biloba L. (species key 2687885) · Source	Taxonomy database plant			Methods, limits and funding Read: full-text
s-nccih-ginkgo Ginkgo (NCCIH Herbs at a Glance), last updated February 2025 · Source	Authoritative guidance n/a			Methods, limits and funding Read: full-text-via-summary

What we do not know yet

No large trial tested ginkgo for preventing memory decline in people younger than 70.
Tea, raw leaf and seed products were not tested in these trials.
The EMA/HMPC herbal monograph, LactMed and LiverTox pages were not read.
Human liver safety, allergy and kidney notes were not researched.
It is not clear which people with dementia, if any, benefit.
Many dementia trials used a branded extract, and some were industry-funded.

How new research is added

New studies are found by a saved PubMed search and placed in a review queue before the page changes.

Lab markers

What changed in blood or saliva tests during trials. A changed number is not the same as feeling or being healthier, and we give no "normal ranges".

Other 7

●

New cases of dementia

No lower on ginkgo in trials

How many people in a trial are newly diagnosed with dementia over several years.

Evidence against

Results and what it means

Why it was measured

To see whether ginkgo lowers the chance of developing dementia.

Statistical vs. clinical meaning

Neither trial showed protection.

Safety implication

Side effects were similar to placebo in both trials.

Study	Result	People	Product
¹	All-cause dementia HR 1.12 (95% CI 0.94 to 1.33); 277 cases on ginkgo vs 246 on placebo	3,069 adults aged 75 or older, median 6.1 years	Ginkgo leaf extract vs placebo
²⁶	Probable Alzheimer disease HR 0.84 (95% CI 0.60 to 1.18); 61 vs 73 cases	2,854 adults aged 70 or older with memory complaints, 5 years	EGb 761 vs placebo

^{1 26}

●

Yearly decline in memory scores

No slower on ginkgo in trials

How fast scores on memory tests fall each year.

Evidence against

Results and what it means

Why it was measured

To see whether ginkgo slows age-related memory loss.

Statistical vs. clinical meaning

No difference in any thinking area.

Safety implication

No extra safety signal reported in this analysis.

Study	Result	People	Product
²⁰	Memory decline 0.043 (ginkgo) vs 0.041 (placebo) per year	3,069 adults aged 72 to 96	Ginkgo leaf extract vs placebo

²⁰

●

Memory test scores in healthy adults

No change in trials

Scores on memory tests in people without memory problems.

Evidence against

Results and what it means

Why it was measured

To see whether ginkgo improves memory in healthy people.

Statistical vs. clinical meaning

No measurable effect.

Safety implication

Not applicable.

Study	Result	People	Product
¹¹	Memory d = -0.04 (95% CI -0.17 to 0.07)	Healthy adults, 13 trials, 1,132 people	Ginkgo vs placebo
²¹	No significant difference on any test	230 healthy adults over 60, 6 weeks	Ginkgo vs placebo

^{11 21}

●

Short Cognitive Performance Test (SKT) in dementia

Lower (better) in some trials in trials

A short test of attention and memory. Lower scores mean better performance.

Low certainty

Results and what it means

Why it was measured

To see whether ginkgo helps thinking scores in people with dementia.

Statistical vs. clinical meaning

A small score change from low-certainty evidence with large differences between trials.

Safety implication

Serious side effects probably no different from placebo at six months.

Study	Result	People	Product
²⁷	MD -1.86 (95% CI -3.48 to -0.24), I2 96%	9 trials, 2,801 people with dementia, six months	Ginkgo vs placebo

²⁷

●

Tinnitus Handicap Inventory score

Little or no change in trials

A questionnaire scored 0 to 100 on how much tinnitus bothers a person.

Very low certainty

Results and what it means

Why it was measured

To see whether ginkgo reduces how disabling tinnitus feels.

Statistical vs. clinical meaning

No meaningful change, very uncertain.

Safety implication

No serious side effects reported.

Study	Result	People	Product
¹⁹	MD -1.35 (95% CI -8.26 to 5.55)	2 trials, 85 people	Ginkgo vs placebo, 3 to 6 months

¹⁹

●

Walking distance

Slightly longer (not significant) in trials

How far a person can walk on a treadmill before leg pain stops them.

Low certainty

Results and what it means

Why it was measured

To see whether ginkgo helps people with artery disease walk further.

Statistical vs. clinical meaning

Small and not significant; likely overstated by missing trials.

Safety implication

Bleeding cautions apply.

Study	Result	People	Product
¹⁶	+3.57 kcal (about 64.5 m), CI -0.10 to 7.23	11 trials, 477 people	Ginkgo vs placebo

¹⁶

●

Chance of acute mountain sickness

Lower trend (not significant) in trials

How many climbers develop acute mountain sickness (headache with other symptoms) at altitude.

Mixed findings

Results and what it means

Why it was measured

To see whether ginkgo lowers the chance of altitude sickness.

Statistical vs. clinical meaning

A trend, not a proven effect.

Safety implication

No safety signal reported in the abstract.

Study	Result	People	Product
²⁵	RR 0.68 (95% CI 0.45 to 1.04)	7 study groups, 451 people	Ginkgo extract vs placebo

²⁵

Safety

What studies and official sources say about side effects, medicines and who should check first. Each point shows what kind of evidence it comes from.

Main points to know 4

Bleeding: the main caution, and the evidence disagrees. NCCIH says ginkgo may increase bleeding risk in people taking anticoagulants such as warfarin. The evidence is mixed. A pooled analysis of 18 trials (1,985 adults) found no effect on platelet clumping, fibrinogen or prothrombin time. A 26-week trial of 513 people with Alzheimer dementia found no change in clotting tests or bleeding time. A crossover study in 12 healthy men found ginkgo did not change warfarin levels or INR. But a large records study of US Veterans on warfarin found that taking ginkgo with warfarin was linked to a higher chance of a bleeding event (hazard ratio 1.38, 95% CI 1.20 to 1.58), and a 2002 case report describes a bleed around the brain in a 78-year-old man taking ginkgo. Records studies and case reports cannot prove cause. If you take a blood thinner, have a bleeding disorder, or are having surgery, tell your doctor or pharmacist about ginkgo first. Meta analysis, randomised trials, observational study, case report and authoritative guidance ^{8 9 6 22 13 14 30}
Ginkgo seeds are poisonous; the leaf extract is a different product. NCCIH says fresh ginkgo seeds are toxic when eaten, and serious side effects have followed roasted seeds or the crude plant. Case reports describe vomiting, diarrhoea and seizures after children and adults ate large amounts of ginkgo seeds or nuts. The seeds contain 4-methoxypyridoxine, a vitamin B6 blocker, and the reports describe recovery after vitamin B6 treatment. Standardised leaf extracts are not the same as seeds, but unstandardised products may contain seed material. Authoritative guidance and case reports ^{30 7 5 4}
Possible link with seizures in people on seizure medicines. A case report describes a man on two seizure medicines who died after a seizure while also taking many supplements including ginkgo; his medicine levels were low, and the authors suggested ginkgo might speed up the breakdown of the medicines. This is a possible explanation, not a proven cause. A healthy-volunteer study found the standardised extract did not change the activity of five major liver enzymes. People with epilepsy should check with their doctor before taking ginkgo. Case report and clinical pharmacology study ^{10 28 4}
Pregnancy and breastfeeding. NCCIH says ginkgo may be unsafe in pregnancy and, near delivery, might cause early labour or extra bleeding. A 2006 review found only weak evidence but advised caution in pregnancy, especially around labour, and said safety during breastfeeding is unknown. Authoritative guidance and review ^{30 2}

Side effects 3

Effect	How often	Severity and recovery	Evidence
Dizziness, stomach or gut upset, headache NCCIH says leaf extract is generally well tolerated and that these are the most common side effects.	Not given as numbers in the sources read.	Usually mild Not stated in the sources read.	Authoritative guidance ³⁰
Serious side effects compared with placebo in trials In people with subjective memory complaints, adverse events may have been higher with ginkgo at three months (very uncertain).	MCI: RR 0.95 (0.82 to 1.09), high certainty. Dementia: RR 0.88 (0.58 to 1.33), low certainty.	Serious events Not applicable.	Meta-analysis ²⁷
Strokes and bleeding events in a long trial This trial was funded by industry (Ipsen).	GuidAge: 65 strokes on ginkgo vs 60 on placebo (RR 1.12, 0.77 to 1.63). Other bleeding or heart events did not differ.	Serious Not applicable.	Randomised controlled trial ²⁶

Liver

No human liver injury was assessed in the sources read for this page. In long animal studies by the US National Toxicology Program, a high-dose ginkgo extract caused liver enlargement and liver cell changes in rats and mice. That is animal evidence at doses far above supplement use and does not show the same effect in people. ¹⁵

How often. No human frequency was found.

Monitoring. No agency monitoring advice was found in the sources read.

This is a safety connection. It is not evidence that Ginkgo biloba supports liver health.

Medicines and supplements 6

With	Why it matters	Importance	Evidence	What to do
Warfarin (anticoagulant) prescription	Ginkgo may affect platelets or clotting; trials of lab measures found no effect, but a records study found more bleeding.	Mixed. A crossover study (12 healthy men, single warfarin dose) found no change in INR or warfarin handling. A US Veterans records study linked ginkgo plus warfarin to more bleeding events (HR 1.38).	Randomised crossover trial and observational study Low certainty ^{6 22 9 30}	NCCIH warns of bleeding risk with anticoagulants such as warfarin. Ask a doctor or pharmacist before using ginkgo.
Aspirin, clopidogrel and other antiplatelet drugs; painkillers such as NSAIDs prescription	Additive effect on bleeding is plausible but not proven.	A Vietnamese hospital records review found ginkgo interactions with antiplatelet drugs and anti-inflammatory painkillers were linked to bleeding risk and abnormal clotting tests; clopidogrel and aspirin were the most frequent. A secondary analysis of a trial found no interaction with aspirin in 105 ginkgo users.	Observational study and secondary trial analysis Low certainty ^{13 9}	Ask a doctor or pharmacist before combining.
Seizure medicines (for example valproate and phenytoin) prescription	The authors of one case report suggested ginkgo might speed their breakdown (a hypothesis).	One fatal case report; a healthy-volunteer study of the extract found no relevant effect on the main liver enzymes.	Case report and clinical pharmacology study Very low certainty ^{10 28}	People with epilepsy should ask their doctor first.
Medicines broken down by major liver enzymes (CYP1A2, 2C9, 2C19, 2D6, 3A) prescription	Tested directly with a cocktail of probe drugs.	In 18 healthy volunteers, the standardised extract had no relevant effect on the activity of these enzymes. Healthy volunteers and one extract only.	Randomised crossover trial Low certainty ²⁸	Ask a pharmacist if you take several medicines.
Ginger supplement	Tested together with ginkgo in the warfarin crossover study.	Neither ginger nor ginkgo alone changed INR or platelet clumping in 12 healthy men.	Randomised crossover trial Low certainty ⁶	Ask a pharmacist about combining supplements.
Vitamin B6 supplement	Ginkgo seeds contain 4-methoxypyridoxine, which works against vitamin B6.	In seed-poisoning case reports, seizures were treated with active vitamin B6. This relates to seeds and nuts, not to refined leaf extract.	Case reports Very low certainty ^{7 5}	Do not eat ginkgo seeds or nuts; ask a doctor if poisoning is suspected.

Who should check first 5

Situation	Advice	Evidence
Taking blood thinners, or before surgery or dental work	NCCIH warns of bleeding risk with anticoagulants. Tell the surgeon, dentist and pharmacist about every supplement. Ask a doctor first.	Authoritative guidance ³⁰
Pregnancy and breastfeeding	NCCIH says ginkgo may be unsafe in pregnancy and might cause early labour or extra bleeding near delivery. Safety while breastfeeding is not well known. Ask a doctor first.	Authoritative guidance and review ^{30 2}
Epilepsy or a history of seizures	Case reports link ginkgo seeds, and possibly ginkgo products taken with seizure medicines, to seizures. Ask a doctor first.	Case reports ^{10 7 4}
Children	No trial in this page tested ginkgo for memory in children. A 2-year-old girl had seizures after eating a large quantity of ginkgo seeds. Keep ginkgo seeds away from children and ask a doctor before giving any supplement.	Case report ⁷
Allergy	Allergy to ginkgo was not researched for this page.	Not researched

Overdose, product quality and regulators

Summary. Ginkgo leaf extract is generally well tolerated in trials, but seeds are poisonous and high-dose animal studies showed liver, thyroid and nose changes. Bleeding cautions are the main practical concern.

Animal. US National Toxicology Program studies of a ginkgo leaf extract in rats and mice for up to 2 years found liver enlargement and liver cell changes, thyroid and nose changes, and more tumours in some groups (thyroid follicular cell adenoma in rats; liver adenoma in some male rats). These were gavage doses far above supplement use.

High dose or long term signals. No human signal was found in the trials read. Animal findings are not proof of the same effect in people.

Overdose response. For seeds: vomiting, diarrhoea, confusion and seizures, treated in case reports with vitamin B6. Call poison control or emergency services.

Genotoxicity. The NTP report included genetic toxicity tests; the results were not given in the abstract read.

Toxic or hazardous parts. Raw or roasted seeds and the crude plant (NCCIH).

Ginkgo leaf products have a high rate of adulteration or mislabelling. A 2024 review of 78 publications found 56.7% of 533 ginkgo leaf samples were adulterated or mislabelled, the highest among five popular herbs. Licensed herbal medicines had a lower risk than food supplements.

Adulteration and label accuracy. 56.7% of 533 ginkgo leaf samples were adulterated or mislabelled; the review warns the data have significant limits. ¹⁷

Seed material in unstandardised products. The authors of a nursing-home study worry that unstandardised ginkgo products may contain plant parts, such as seed material, linked to seizures. ⁴

Body	Action	Date
NCCIH (US National Institutes of Health) (United States)	Says ginkgo extract did not reduce dementia risk in three large studies of older adults; evidence for dementia symptoms is inconsistent. Warns of bleeding risk with anticoagulants such as warfarin, that fresh seeds are toxic, that ginkgo may be unsafe in pregnancy, and that leaf extract is generally well tolerated. source	2025-02

When to get medical help

Sudden severe headache, confusion, weakness on one side, or any bleeding that will not stop, especially in someone taking a blood thinner: get emergency help.
Someone, especially a child, has vomiting, diarrhoea, confusion or a seizure after eating ginkgo seeds or nuts: call poison control or emergency services.
Unexplained bruising, blood in urine or stool, or black stools: contact a doctor soon.

Stop using the product and contact a clinician or emergency service. In the US, Poison Control is 1-800-222-1222.

General information only, not medical advice. Ask a clinician or pharmacist before use, especially with medicines, in pregnancy or with a health condition. See the Natural Remedy Safety guide.

Frequently asked questions

What is ginkgo biloba?

Ginkgo biloba is a tree native to China. The supplement is usually a standardised extract of its leaves, sold as capsules, tablets or drops.

^{29 30}

Does ginkgo improve memory?

Not in healthy adults. A pooled analysis of trials found effects close to zero for memory, and a six-week trial in healthy adults over 60 found no difference from placebo.

^{11 21}

Does ginkgo prevent dementia or Alzheimer disease?

Two large trials in older adults found it did not. NCCIH says three large studies found no reduction in dementia risk.

^{1 26 30}

Can ginkgo help people who already have dementia?

The 2026 Cochrane review found low-certainty hints of small to moderate benefits at six months in dementia, with very large differences between trials. It is not a proven treatment and does not cure or reverse dementia.

^{27 24}

Does ginkgo help mild cognitive impairment?

Probably not. Cochrane found little or no effect on overall status, thinking or daily activities at six months, with moderate certainty.

²⁷

Does ginkgo increase bleeding?

The evidence is mixed. Trial data on clotting tests showed no effect, but a large records study linked ginkgo plus warfarin to more bleeding, and there are case reports. NCCIH warns about anticoagulants.

^{30 8 22 14}

Can I take ginkgo with warfarin or aspirin?

Ask your doctor or pharmacist first. NCCIH warns of bleeding risk with anticoagulants such as warfarin. A crossover study found no change in warfarin handling, while a records study found more bleeding.

^{30 6 22 9}

Are ginkgo seeds safe to eat?

No. NCCIH says fresh seeds are toxic. Case reports describe seizures after eating large amounts of seeds or nuts.

^{30 7 5}

Is ginkgo safe in pregnancy or breastfeeding?

NCCIH says ginkgo may be unsafe in pregnancy and, near delivery, might cause early labour or extra bleeding. Safety while breastfeeding is not well known. Ask a doctor first.

^{30 2}

What are the side effects?

NCCIH says leaf extract is generally well tolerated; the most common side effects are dizziness, stomach or gut upset and headache.

³⁰

Does ginkgo help ringing in the ears or leg pain?

Evidence is weak. Cochrane found little or no difference for tinnitus (very uncertain) and no clinically significant benefit for walking distance in claudication.

^{19 16}

Are ginkgo supplements reliable?

Not always. A 2024 review found 56.7% of 533 ginkgo leaf samples were adulterated or mislabelled. Ask a pharmacist.

¹⁷

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Editorial transparency

Written by: AlternativeMed editorial team. Research compiled with AI assistance, then checked against the sources listed.
Medical review: None. This page has not been reviewed by a physician or pharmacist.
First published: 2026-10-26
Last substantive update: 2026-10-26
How we research: We started from our existing ginkgo herb profile, then re-read each PubMed abstract used here and a summary of the NCCIH page and the GBIF record. Only abstracts were read for studies. The EMA monograph was not read.
How we rate evidence: See "How we rate evidence" in the Evidence tab.
Independence: No product is promoted on this page. No affiliate links are shown. Some trials were funded by the extract's makers; this is flagged where known.

Sources 30

Each source was opened and checked. Where we read only the abstract, it says so. The small numbers in the text point here.

DeKosky ST, Williamson JD, Fitzpatrick AL et al.. Ginkgo biloba for prevention of dementia: a randomized controlled trial.. JAMA. 2008. PMID 19017911. DOI 10.1001/jama.2008.683. (abstract)
Dugoua JJ, Mills E, Perri D et al.. Safety and efficacy of ginkgo (Ginkgo biloba) during pregnancy and lactation.. Can J Clin Pharmacol. 2006. PMID 17085776. (abstract)
Gong W, Chen C, Dobes C et al.. Phylogeography of a living fossil: pleistocene glaciations forced Ginkgo biloba L. (Ginkgoaceae) into two refuge areas in China with limited subsequent postglacial expansion.. Mol Phylogenet Evol. 2008. PMID 18554931. DOI 10.1016/j.ympev.2008.05.003. (abstract)
Harms SL, Garrard J, Schwinghammer P et al.. Ginkgo biloba use in nursing home elderly with epilepsy or seizure disorder.. Epilepsia. 2006. PMID 16499756. DOI 10.1111/j.1528-1167.2006.00424.x. (abstract)
Jang HS, Roh SY, Jeong EH et al.. Ginkgotoxin Induced Seizure Caused by Vitamin B6 Deficiency.. J Epilepsy Res. 2015. PMID 26819944. DOI 10.14581/jer.15018. (abstract)
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. PMID 15801937. DOI 10.1111/j.1365-2125.2005.02322.x. (abstract)
Kajiyama Y, Fujii K, Takeuchi H et al.. Ginkgo seed poisoning.. Pediatrics. 2002. PMID 11826216. DOI 10.1542/peds.109.2.325. (abstract)
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. PMID 21923430. DOI 10.1592/phco.31.5.490. (abstract)
Kloft C, Hoerr R. EGb 761(®) Does Not Affect Blood Coagulation and Bleeding Time in Patients with Probable Alzheimer's Dementia-Secondary Analysis of a Randomized, Double-Blind Placebo-Controlled Trial.. Healthcare (Basel). 2021. PMID 34946404. DOI 10.3390/healthcare9121678. (abstract)
Kupiec T, Raj V. Fatal seizures due to potential herb-drug interactions with Ginkgo biloba.. J Anal Toxicol. 2005. PMID 16419414. DOI 10.1093/jat/29.7.755. (abstract)
Laws KR, Sweetnam H, Kondel TK. Is Ginkgo biloba a cognitive enhancer in healthy individuals? A meta-analysis.. Hum Psychopharmacol. 2012. PMID 23001963. DOI 10.1002/hup.2259. (abstract)
Liu XW, Yang JL, Niu W et al.. Human pharmacokinetics of ginkgo terpene lactones and impact of carboxylation in blood on their platelet-activating factor antagonistic activity.. Acta Pharmacol Sin. 2018. PMID 30054600. DOI 10.1038/s41401-018-0086-7. (abstract)
Mai NTQ, Hieu NV, Ngan TT et al.. Impact of Ginkgo biloba drug interactions on bleeding risk and coagulation profiles: A comprehensive analysis.. PLoS One. 2025. PMID 40198642. DOI 10.1371/journal.pone.0321804. (abstract)
Miller LG, Freeman B. Possible subdural hematoma associated with Ginkgo biloba.. J Herb Pharmacother. 2002. PMID 15277097. (abstract)
National Toxicology Program. Toxicology and carcinogenesis studies of Ginkgo biloba extract (CAS No. 90045-36-6) in F344/N rats and B6C3F1/N mice (Gavage studies).. Natl Toxicol Program Tech Rep Ser. 2013. PMID 23652021. (abstract)
Nicolaï SP, Kruidenier LM, Bendermacher BL et al.. Ginkgo biloba for intermittent claudication.. Cochrane Database Syst Rev. 2013. PMID 23744597. DOI 10.1002/14651858.CD006888.pub3. (abstract)
Orhan N, Gafner S, Blumenthal M. Estimating the extent of adulteration of the popular herbs black cohosh, echinacea, elder berry, ginkgo, and turmeric - its challenges and limitations.. Nat Prod Rep. 2024. PMID 39108221. DOI 10.1039/d4np00014e. (abstract)
Riepe M, Hoerr R, Schlaefke S. Ginkgo biloba extract EGb 761 is safe and effective in the treatment of mild dementia - a meta-analysis of patient subgroups in randomised controlled trials.. World J Biol Psychiatry. 2025. PMID 39895346. DOI 10.1080/15622975.2024.2446830. (abstract)
Sereda M, Xia J, Scutt P et al.. Ginkgo biloba for tinnitus.. Cochrane Database Syst Rev. 2022. PMID 36383762. DOI 10.1002/14651858.CD013514.pub2. (abstract)
Snitz BE, O'Meara ES, Carlson MC et al.. Ginkgo biloba for preventing cognitive decline in older adults: a randomized trial.. JAMA. 2009. PMID 20040554. DOI 10.1001/jama.2009.1913. (abstract)
Solomon PR, Adams F, Silver A et al.. Ginkgo for memory enhancement: a randomized controlled trial.. JAMA. 2002. PMID 12186600. DOI 10.1001/jama.288.7.835. (abstract)
Stoddard GJ, Archer M, Shane-McWhorter L et al.. Ginkgo and Warfarin Interaction in a Large Veterans Administration Population.. AMIA Annu Symp Proc. 2015. PMID 26958257. (abstract)
Strømgaard K, Nakanishi K. Chemistry and biology of terpene trilactones from Ginkgo biloba.. Angew Chem Int Ed Engl. 2004. PMID 15038029. DOI 10.1002/anie.200300601. (abstract)
Tan MS, Yu JT, Tan CC et al.. Efficacy and adverse effects of ginkgo biloba for cognitive impairment and dementia: a systematic review and meta-analysis.. J Alzheimers Dis. 2015. PMID 25114079. DOI 10.3233/JAD-140837. (abstract)
Tsai TY, Wang SH, Lee YK et al.. Ginkgo biloba extract for prevention of acute mountain sickness: a systematic review and meta-analysis of randomised controlled trials.. BMJ Open. 2018. PMID 30121603. DOI 10.1136/bmjopen-2018-022005. (abstract)
Vellas B, Coley N, Ousset PJ et al.. Long-term use of standardised Ginkgo biloba extract for the prevention of Alzheimer's disease (GuidAge): a randomised placebo-controlled trial.. Lancet Neurol. 2012. PMID 22959217. DOI 10.1016/S1474-4422(12)70206-5. (abstract)
Wieland LS, Ludeman E, Chi Y et al.. Ginkgo biloba for cognitive impairment and dementia.. Cochrane Database Syst Rev. 2026. PMID 41641880. DOI 10.1002/14651858.CD013661.pub2. (abstract)
Zadoyan G, Rokitta D, Klement S et al.. Effect of Ginkgo biloba special extract EGb 761® on human cytochrome P450 activity: a cocktail interaction study in healthy volunteers.. Eur J Clin Pharmacol. 2012. PMID 22189672. DOI 10.1007/s00228-011-1174-5. (abstract)
. GBIF Backbone Taxonomy: Ginkgo biloba L. (species key 2687885). . . (full-text)
. Ginkgo (NCCIH Herbs at a Glance), last updated February 2025. . . (full-text-via-summary)

Where to buy

Check the label first. Whatever you buy, look for these:

The amount of the active ingredient per serving, not just the front-label claim
A third-party testing mark (USP, NSF or ConsumerLab)
Other ingredients and allergens
Ask a pharmacist about interactions with your medicines

Talk to a pharmacist or doctor before you start any supplement, especially if you take medicines. See the Safety tab for interactions.

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Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.