Ginkgo Biloba (leaf extract)
Ginkgo biloba is a "living fossil" — the sole surviving species of a tree lineage roughly 200 million years old. Its leaf extract is one of the most-studied herbal preparations for memory and circulation, but the best-quality reviews are inconsistent or show no clear benefit, and there is no UK-authorised health claim for it. The trial evidence is anchored on the EGb 761 standardised extract (24% flavone glycosides, 6% terpene lactones); generic leaf powder is not equivalent. Ginkgo carries a meaningful drug-interaction profile, particularly with blood-thinning and anti-clotting medicines.
Camden Medicals editorial · Last reviewed 12 June 2026 · Next review June 2027
- Cross-checked against
- NHS
- NICE
- BNF
- EFSA
- FSA
Camden's editorial team independently graded each health claim below on the strength of the published evidence — see the grade beside every condition.
- Class
- Botanical
- Typical daily dose
- Trials of cognitive and circulation use generally used 120-240 mg/day of standardised leaf extract (24% flavone glycosides + 6% terpene lactones), split as 60-120 mg twice daily for 12-24 weeks. This describes the studied range; it is not a recommendation to take it.
- Top use evidence
- Mixed
On this page
What it is
Ginkgo biloba is a deciduous tree native to China, cultivated worldwide as an ornamental and for medicinal use of its fan-shaped leaves. The leaf extract used in supplements is typically a 50:1 hydroalcoholic extract; the EGb 761 preparation (Schwabe Pharmaceuticals) is the trade name with the longest research and regulatory track record.
The bioactive markers are flavone glycosides (quercetin, kaempferol, and isorhamnetin glycosides) and terpene lactones (ginkgolides A, B, C, J, and bilobalide). The EGb 761 standard is 24% flavone glycosides and 6% terpene lactones — values set decades ago to reflect the spectrum used in the original German clinical research.
Ginkgolic acids are the safety-pivot constituents — irritant phenolic acids restricted to no more than 5 ppm in EGb 761 and other research-grade extracts. Generic ginkgo leaf powder or low-quality extracts can deliver ginkgolic acids at much higher levels.
Camden's encyclopaedia look-for bar is a standardised extract with declared flavone-glycoside and terpene-lactone percentages, plus ginkgolic acid at no more than 5 ppm. A generic "ginkgo 2000 mg" with no standardisation declared is not the same product as research-grade EGb 761.
At a glance
- Leaf extract of the Ginkgo biloba tree. The trial-grade material is the standardised EGb 761 extract — 24% flavone glycosides plus 6% terpene lactones. Generic "ginkgo 2000 mg" without standardisation declared is not the same product.
- No UK-authorised health claim. The botanical claims sit on the EFSA on-hold list, so a product page must stay descriptive — no memory, circulation or tinnitus benefit may be claimed.
- Most-discussed for age-related memory changes, peripheral arterial disease / claudication, and tinnitus or vertigo — but the recent Cochrane reviews are inconsistent or null, and the large GEM prevention trial (3,069 older adults) found no effect on dementia.
- Significant drug interactions: warfarin, DOACs, antiplatelets (clopidogrel, aspirin), SSRIs/MAOIs, and anticonvulsants. Standard advice is to stop at least 1 week before any planned surgery and to talk to your pharmacist or GP first if you take any of these.
What people use it for
Adults with mild age-related memory changes (not dementia)
Ginkgo is widely taken for everyday forgetfulness and "brain fog". The Cochrane review of ginkgo for cognitive impairment and dementia pooled 36 trials and concluded that the evidence of a predictable, clinically meaningful benefit is inconsistent and unreliable. Some trials of the standardised extract reported modest gains; others showed nothing. The current evidence does not support routine use for this purpose. Persistent or worsening memory problems need a GP assessment rather than self-treatment. [5,10]
Popular, not provenMixedHealthy adults hoping to sharpen memory or to prevent dementia
Ginkgo is heavily marketed online as a "memory booster" and a way to ward off dementia. The largest test of that idea — the NIH-funded GEM trial of 3,069 older adults taking ginkgo 120 mg twice daily — found no effect on the rate of dementia or Alzheimer's disease. The Alzheimer's Society advises treating any supplement sold to prevent or slow dementia with strong scepticism. The available evidence does not support this use. [7]
Not supportedInsufficientAdults with peripheral arterial disease / intermittent claudication
Ginkgo is sometimes taken to walk further with less leg pain. Earlier trials suggested a small effect, but the Cochrane review of ginkgo for claudication did not find a clinically significant benefit over placebo. The NHS and NICE pathway for peripheral arterial disease is a supervised exercise programme plus cardiovascular risk-factor management (stopping smoking, statin and blood-pressure treatment); ginkgo is not part of it. [6]
Popular, not provenMixedAdults with tinnitus or vertigo
Ginkgo is a common self-treatment for ringing in the ears. The Cochrane review found no reliable evidence that it helps tinnitus that is itself the main complaint. Tinnitus that significantly affects daily life needs an NHS audiology or ENT pathway rather than a supplement. [11]
Popular, not provenInsufficient
How it works
Ginkgo extract has documented effects on several pathways: inhibition of platelet-activating factor (PAF), which is relevant to the bleeding- interaction signal; antioxidant activity through flavonoid free-radical scavenging; modulation of monoamine oxidase, which underlies the theoretical MAOI interaction; nitric-oxide-mediated relaxation of cerebral and peripheral blood vessels; and modulation of GABA-A and serotonergic signalling. How any single one of these translates into a measurable effect in older adults is incompletely characterised, and the drug-interaction profile largely reflects the PAF-inhibition and serotonergic pathways.
Common myths
Myth"Ginkgo prevents dementia."
RealityIt does not. The largest prevention trial (the GEM trial, NIH-funded, 3,069 older participants over roughly 6 years) found no effect on the rate of dementia or Alzheimer's disease. Ginkgo is not on the UK NICE or NHS dementia-prevention pathways, and the Alzheimer's Society advises scepticism towards any supplement marketed for this. [7]
Myth"All ginkgo supplements are the same."
RealityThey are not. The trial evidence is on standardised extracts with 24% flavone glycosides and 6% terpene lactones (EGb 761 and equivalent). Generic leaf powder or low-extract-ratio products deliver different — and often substantially less — bioactive content.
Myth"Ginkgo is risk-free because it is "natural"."
RealityGinkgo has a meaningful drug-interaction list — warfarin and DOAC bleeding case reports, MAOI and SSRI serotonergic theory, anticonvulsant interactions. A systematic review of bleeding case reports (Bent 2005) documented intracranial and other bleeds in ginkgo users. Stopping at least 1 week before surgery is a routine pre-operative instruction. It is not a casual self-treatment for someone on multiple medicines. [8]
Common online questions
Synthesised from the questions UK shoppers most often ask online about Ginkgo Biloba (leaf extract). Each answer is editorial and links to its evidence in the Sources list below.
How long do people take ginkgo before deciding it works?
Trials of cognitive use typically ran for 12 to 24 weeks. A reasonable reading is that if there is no noticeable change after about 12 weeks of daily standardised-extract use, ginkgo is unlikely to be the right tool for the symptom. Persistent cognitive symptoms need a GP review.
Can ginkgo be taken with warfarin?
This is a question to put to your anticoagulation team first. Ginkgo has multiple published case reports of increased bleeding (intracranial, gastrointestinal, surgical) in people on warfarin. Even where the INR is unchanged, the platelet-activating-factor pathway can raise bleeding-event risk. The conservative position is to avoid the combination unless an anticoagulation clinic is specifically supervising it. [8]
Is it necessary to stop ginkgo before surgery?
Standard pre-operative advice is to stop ginkgo at least 1 week before any planned surgery, including dental extractions, and to tell the anaesthetist about it. The bleeding pathway is the principal peri-operative concern. Talk to your surgical team or pharmacist about the exact timing. [8]
Is ginkgo suitable in pregnancy?
The conservative position is to avoid it. The bleeding pathway plus limited pregnancy safety data make ginkgo a poor choice during pregnancy and breastfeeding. Talk to your midwife, GP or pharmacist before taking any supplement in pregnancy.
Are ginkgo seeds the same as the leaf extract?
No, and eating them is not advisable. Ginkgo seeds (the kernel inside the smelly fruit) contain 4-O-methylpyridoxine, a vitamin-B6 antagonist that has caused seizures and, in high-intake case reports, deaths. The leaf extract used in supplements does not contain it at meaningful levels.
🔬 Camden’s evidence review
The research Camden reviewed, graded on its strength. This is our own appraisal — it sits beneath the official guidance above, never above it.
Cognitive function in dementia and pre-dementia
MixedEvidencemixedThe research Camden reviewed: Cochrane CD003120.pub3 (Birks & Grimley Evans 2009) pooled 36 trials of ginkgo extract for cognitive impairment and dementia and judged the results inconsistent and unreliable, with the more rigorous recent trials least favourable. The large NIH-funded GEM trial (DeKosky 2008, JAMA, n=3,069) found no effect on dementia incidence in older adults. UK NICE guidance (NG97) does not list ginkgo for dementia, and the Alzheimer's Society advises scepticism towards supplements marketed for dementia. [5,10,7]
Intermittent claudication / peripheral arterial disease
MixedEvidencemixedThe research Camden reviewed: Cochrane CD006888.pub3 (Nicolai 2013) did not find a clinically significant improvement in pain-free walking distance with ginkgo over placebo, tempering earlier more positive meta-analyses. The NICE pathway (CG147) is supervised exercise plus cardiovascular-risk management, not a supplement. [6]
Tinnitus
InsufficientEvidenceinsufficientThe research Camden reviewed: Cochrane CD003852.pub3 (Hilton 2013) found no reliable evidence of benefit for tinnitus that is the primary complaint. NICE NG155 (tinnitus) does not list ginkgo among its management options. [11]
Macular degeneration
InsufficientEvidenceinsufficientThe research Camden reviewed: evidence is insufficient. The NHS pathway for age-related macular degeneration is ophthalmology referral, anti-VEGF therapy where indicated, and the AREDS-formulation where appropriate — not ginkgo.
Effect matrix — per-condition evidence
Per-outcome summary of the published trial corpus: dose ranges studied, duration, evidence grade, and direction of effect. Each row is a citable claim.
| Outcome | Population | Dose | Duration | Evidence | Direction | Sources |
|---|---|---|---|---|---|---|
| Cognitive impairment and dementia (symptomatic) | older adults | 120–240 mg | 12–52 wk | MixedEvidencemixed | mixed | PMID 19160216 PMID 19017911 |
| Cochrane CD003120.pub3 (Birks 2009, PMID 19160216) pooled 36 trials; results inconsistent. GEM prevention trial (PMID 19017911) null for dementia incidence. | ||||||
| Intermittent claudication / peripheral arterial disease | adults | 120–240 mg | 12–24 wk | MixedEvidencemixed | no change | — |
| Cochrane CD006888.pub3 (Nicolai 2013) found no clinically significant benefit over placebo for walking distance. | ||||||
| Tinnitus (primary complaint) | adults | — | — | InsufficientEvidenceinsufficient | not assessed | — |
| Cochrane CD003852.pub3 (Hilton 2013): no reliable evidence of benefit; effect not assessable. | ||||||
| Bleeding events (safety signal) | adults | — | — | LimitedEvidencelimited | not assessed | PMID 16050865 |
| Bent 2005 (PMID 16050865) systematic review of bleeding case reports (intracranial and other). Case-report evidence; causation not established but the PAF-inhibition mechanism is biologically plausible. | ||||||
Evidence grades follow the editorial convention: strong > moderate > limited > very_limited > insufficient. Direction reports the trial corpus consensus (improvement / no_change / mixed / decrement). Schema cross-emitted at MedicalSubstance.relevantClinicalCondition[].
Safety
Ginkgo carries a meaningful drug-interaction profile, particularly with anticoagulants and antiplatelets. Standard advice is to stop at least 1 week before any planned surgery, and to talk to a clinician before use if you take prescribed medicine. Avoid in pregnancy and breastfeeding.
Talk to your pharmacist or GP first if you:
- You take warfarin, a DOAC (apixaban, rivaroxaban, dabigatran, edoxaban), or any other anticoagulant.
- You take aspirin, clopidogrel, prasugrel, ticagrelor, or any antiplatelet.
- You take SSRIs, SNRIs, MAOIs, or other antidepressants.
- You take antiepileptic / anticonvulsant medication.
- You take diabetes medication — a glycaemic interaction is possible.
- You have any planned surgery in the next 14 days — stop at least 1 week before and tell your anaesthetist.
- You are pregnant, breastfeeding, or trying to conceive — avoid.
- You are considering it for a child — paediatric use is not standard.
Common side effects: Mild headache, dizziness, gastrointestinal upset. Allergic reactions in people allergic to the poison-ivy / cashew family (cross-reactivity with ginkgolic acids).
Pregnancy and breastfeeding
Bleeding-risk pathway plus insufficient pregnancy safety data; avoid.
Insufficient data; avoid.
Talk to your GP, midwife, or pharmacist before starting any supplement during pregnancy or breastfeeding.
More clinical detail (for clinicians and informed readers)
Contraindications
- Pregnancy and breastfeeding.
- Active bleeding disorder or scheduled surgery within 14 days.
- Active epilepsy or seizure disorder (without specialist supervision).
- Known Anacardiaceae-family allergy.
Drug interactions
- Warfarin, DOACs (apixaban, rivaroxaban, dabigatran, edoxaban) — case reports of bleeding events; PAF-inhibition pathway.
- Aspirin, clopidogrel, other antiplatelets — additive bleeding risk.
- NSAIDs at high dose — additive bleeding risk.
- SSRIs, SNRIs, MAOIs — theoretical serotonergic effect; case reports.
- Antiepileptics (phenytoin, valproate, carbamazepine) — theoretical reduction in efficacy; ginkgo seed is the seizure pivot but leaf extract is not free of risk.
- Diabetes medication — a glycaemic interaction is possible.
- CYP3A4 / CYP2C9 / CYP2C19 substrates — ginkgo modulates these enzymes; clinical significance varies.
This is not an exhaustive list. Always tell your prescriber and pharmacist about every supplement you take.
Common side effects
- Headache, dizziness, mild gastrointestinal symptoms.
- Mild palpitations or anxiety in a minority.
Rare side effects
- Bleeding events — intracranial, gastrointestinal, and surgical case reports.
- Allergic reactions — cross-reactivity with the poison ivy / mango / cashew family (Anacardiaceae) reported.
- Seizures — historic case reports, particularly with ginkgo seed, but also rarely reported with leaf extract in people with a seizure disorder.
How to take it
- Typical supplemental range
- Trials of cognitive and circulation use generally used 120-240 mg/day of standardised leaf extract (24% flavone glycosides + 6% terpene lactones), split as 60-120 mg twice daily for 12-24 weeks. This describes the studied range; it is not a recommendation to take it.
- Timing
- Twice-daily dosing was common in trials. No specific food requirement.
How to spot quality
Look for
- Ginkgo biloba leaf extract named — not whole leaf or seed.
- Standardisation declared: at least 24% flavone glycosides AND at least 6% terpene lactones.
- Ginkgolic acid content declared at no more than 5 ppm.
- Extract ratio stated (typically 50:1).
- GMP-certified manufacture; ideally identity verification (substitution / adulteration is a documented industry issue).
Red flags
- Generic "ginkgo extract" with no standardisation declared.
- No ginkgolic acid disclosure.
- Leaf powder labelled at the same milligrams as a research-grade extract.
- Marketing that implies dementia prevention, a "memory boost", or reversal of cognitive decline.
Commonly combined with
Other ingredients that share a biological pathway, cofactor relationship, or evidence-backed protocol with this one. Mechanisms below cite primary physiology — not folk pairing. Doses are literature ranges, not recommendations. Talk to your pharmacist or GP before changing your stack, especially if you take prescription medication.
Vitamin E (alpha-tocopherol)
Limited evidenceCardiovascular / cognitive antioxidant cluster — both ginkgo flavonoids and vitamin E feature in mixed-evidence cognitive-decline supplementation.
Ginkgo flavonoid + terpene-lactone signalling on platelet activation factor; vitamin E lipophilic antioxidant. Different mechanisms; commonly co-formulated.
Evidence: UK Article 13.1 vitamin E cell-protection claim authorised. No authorised claim for ginkgo. [12]
Doses studied: 120-240 mg ginkgo standardised extract (24% flavone glycosides + 6% terpene lactones) + 12 mg vitamin E daily.
Fish Oil (Long-Chain Omega-3 EPA / DHA, Marine Source)
Limited evidenceCardiovascular cluster — both have anticoagulant / platelet-modulation signals. CONTRAINDICATION-LEVEL when combined with warfarin.
Ginkgo platelet-activation-factor inhibition; fish oil EPA / DHA platelet aggregation modulation. Additive bleeding risk. CONTRAINDICATION with warfarin / DOACs without anticoagulation-clinic input.
Evidence: Bleeding-risk warning; talk to prescriber.
Doses studied: Combination requires anticoagulation-clinic input if on warfarin / DOAC.
St John's Wort (Hypericum perforatum)
Limited evidenceDrug-interaction concern cluster — disclose both to any prescriber. St John's Wort is the canonical CYP / P-gp inducer reference.
Both have documented drug-interaction profiles. St John's Wort is the more-aggressive inducer. Camden st-johns-wort is the interaction reference.
Evidence: Camden st-johns-wort is the cluster reference.
Doses studied: Disclose any combination to a prescribing GP / pharmacist.