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Ginkgo biloba

Ginkgo biloba

Herbs & Botanicals

What ginkgo biloba may help with

Ranked by how strong the human evidence is — best supported first.

Best supportedBlood flowLimited evidence· 2 sources

Then, in order

About Ginkgo biloba

A leaf extract standardised to 24% flavone glycosides and 6% terpene lactones, with ginkgolic acids limited because of their allergenic potential. Ginkgo seed is a separate and more toxic material.

Ginkgo is the closest thing this category has to a definitive negative result. The Ginkgo Evaluation of Memory study followed more than 3,000 older adults for around six years on 240 mg daily and found no reduction in dementia incidence or in the rate of cognitive decline, and a European trial reached the same conclusion. Smaller trials in existing dementia and in tinnitus report scattered benefits, which sit awkwardly against the large negative studies.

Sold as
Standardised leaf extract tablet, Capsule, Liquid extract, Tea (unstandardised)
Standardised to
EGb 761 and similar extracts: 24% flavone glycosides, 6% terpene lactones, under 5 ppm ginkgolic acids — a product without this marker may not resemble what was studied.
Also known as
Maidenhair tree, EGb 761, Kew tree

What the research used

The amounts, forms and durations published trials of Ginkgo biloba actually administered.

These are the amounts published trials administered — not a recommendation, and not a dose to copy. Trial participants were screened, supervised and given a characterised preparation. What is in a retail bottle is frequently not what was studied, and the amount that suits one person is not general advice.

  • Studied for Cognitive decline and dementia

    120–240 mg

    Moderate

    Standardised leaf extract, once or twice daily · 24% flavone glycosides / 6% terpene lactones · 6 months to 6 years

    The largest and longest trials at 240 mg per day found no reduction in dementia incidence. Positive results come mostly from shorter trials in people who already had cognitive impairment.

  • Studied for Intermittent claudication and tinnitus

    120–240 mg

    Limited

    Standardised extract, divided doses · 8–24 weeks

    Pooled effects on walking distance are small enough that reviewers question their clinical meaning, and tinnitus trials are inconsistent.

This is general information about food, not medical advice. It cannot diagnose, treat or replace guidance from a clinician who knows your history.

When it was taken

Each window says whether a trial compared it against an alternative, or whether it is convention and pharmacology. Most timing advice is the second kind.

None of the timings below were directly compared in a trial. They reflect how the research happened to dose, or what the pharmacology implies — which is not the same as a timing being better.

  • Split through the day

    Limited

    Most trials split the daily amount into two doses; the largest used 120 mg twice daily. No trial compared once-daily against split dosing for outcomes.

    Timing was not directly compared. This reflects convention or how the compound behaves in the body, not a trial showing this window works better.

The evidence in depth

Best supported: Limited

What each association actually rests on, and the papers behind it. A rating describes the state of the research, not how promising the supplement sounds. How we rate evidence.

Blood flow

Circulation
Limited evidence

Some trials in peripheral arterial disease report small increases in pain-free walking distance. Reviewers describe the effect as too small to be clinically meaningful.

Limited evidence. Early human work, or mostly lab and animal research.

View the 2 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Cognitive ageing

Brain & Cognitive Health
Limited evidence

Large long-term trials in older adults found no reduction in dementia incidence or in the rate of cognitive decline with 240 mg daily. Smaller trials in people with existing dementia report modest improvements on cognitive scales, which is the weaker part of the evidence base.

What may be going on: Ginkgo flavonoids and terpene lactones affect platelet-activating factor and cerebral blood flow in preclinical work.

Limited evidence. Early human work, or mostly lab and animal research.

View the 1 source

Deep research mode adds each paper’s own conclusion and stated limitations.

Cognitive function

Brain & Cognitive Health
Not enough evidence

Evidence is limited for ginkgo and memory in healthy adults. Trials in people without cognitive impairment have generally found no meaningful difference from placebo.

Not enough evidence. Not enough human research to say anything useful yet.

View the 4 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Things to know

Interactions, contraindications and dose limits, most serious first. Concentrated extracts interact with medication in ways the whole plant does not, so this section carries more weight here than it does on a food page.

  • Interaction

    Bleeding risk

    Interacts withWarfarin, direct oral anticoagulants, aspirin, clopidogrel, NSAIDs

    Case reports describe intracranial and post-operative bleeding associated with ginkgo, and it inhibits platelet-activating factor. It should not be combined casually with warfarin, direct oral anticoagulants, aspirin or NSAIDs, and is routinely stopped one to two weeks before surgery.

  • Interaction

    Seizure threshold and anticonvulsants

    Interacts withValproate, phenytoin, carbamazepine

    Ginkgotoxin, present in seeds and in trace amounts in leaf material, can lower the seizure threshold, and ginkgo may reduce the effectiveness of valproate and phenytoin. It is avoided in epilepsy.

  • Worth knowing

    Ginkgo seeds are toxic

    Raw or lightly cooked ginkgo seeds contain enough ginkgotoxin to cause vomiting and seizures, with fatalities documented in children. Seeds and leaf extract are entirely different exposures.

  • Interaction

    Drug metabolism

    Interacts withOmeprazole, efavirenz, CYP2C19 substrates

    Ginkgo affects CYP2C19 and other enzymes in human studies, which can lower levels of medicines including omeprazole and some antiretrovirals.

  • Allergy

    Ginkgolic acid allergy

    Ginkgolic acids are related to the allergens in poison ivy and cashew shell. Quality extracts limit them to under 5 parts per million; unstandardised products and teas may not.

  • Avoid

    Pregnancy

    Ginkgolides have been detected in cord blood and bleeding risk around delivery is a concern. It is generally avoided in pregnancy.

Evidence ratings on this page: 2 limited evidence, 1 not enough evidence.

Supplements are sold in the US without pre-market review of efficacy or safety. Nothing on this page is a recommendation to take Ginkgo biloba, or a dose to follow.