Ginkgo biloba is a leaf extract from the ginkgo tree, sold as a supplement for memory and “brain health.” The U.S. National Center for Complementary and Integrative Health (NCCIH) says there is no conclusive evidence that ginkgo helps any health condition. Large trials found it did not prevent dementia, and the best case for it is a small, inconsistent benefit for symptoms in people who already have dementia.
Quick facts
| Item | What the sources say |
|---|---|
| Forms | Leaf extract is the most common form (NCCIH). Products come as capsules, teas and liquid extracts, and a standardized concentrated extract called EGb 761 is used in many trials. Fresh and roasted seeds and the crude plant are toxic. |
| Doses used in studies | 240 mg a day of the standardized extract in the mild dementia analysis. A reported “more than 120 mg twice a day” in the largest prevention trial. |
| Typical study length | From 6 weeks (healthy older adults) to 3 to 6 months (cognitive impairment and dementia trials) and a median of 6 years (the large prevention trial). |
| Main studied uses | Preventing dementia, memory in healthy people, mild cognitive impairment, dementia symptoms. Smaller bodies of research cover anxiety, stroke recovery, tinnitus, blood pressure and others. |
What do human studies show, use by use?
Preventing dementia: no benefit in the largest trial
The Ginkgo Evaluation of Memory (GEM) study, funded by two U.S. National Institutes of Health institutes, randomly assigned more than 3,000 people aged 75 or older to ginkgo or placebo for a median of 6 years. Participants had normal thinking or mild cognitive impairment. According to NCCIH, dementia and Alzheimer’s disease rates were no different between the groups. NCCIH says three large studies in all reached the same result. A separate randomized trial in people aged 85 or older with normal thinking, summarized in Nature Reviews Neurology, found no clear effect on cognitive decline and noted an increased risk of stroke in those taking the extract.
Memory in healthy older adults: no difference
A 2002 double-blind trial reported in JAMA gave ginkgo or placebo to 230 healthy volunteers over 60. After 6 weeks, there were no significant differences on 14 memory, attention and concentration tests or on ratings by companions. Industry groups responded that the evidence in unimpaired adults is mixed and that this was one study among many. NCCIH adds that much research on healthy people is low quality, so it is uncertain whether ginkgo changes thinking in healthy adults.
Mild cognitive impairment: probably little or no effect
The latest Cochrane review covered 82 randomized trials with 10,613 people. Twelve of them (1,913 people) tested ginkgo against placebo in mild cognitive impairment. At six months, moderate-certainty evidence showed probably little or no effect on overall condition, thinking test scores or everyday tasks. Serious side effects did not differ from placebo (high-certainty evidence).
Dementia symptoms: possible small benefit, inconsistent results
In the same Cochrane review, 13 trials (3,288 people) compared ginkgo with placebo in dementia. At six months, low-certainty evidence suggested modest improvements in overall condition, thinking and daily activities. Results varied widely from study to study, so the reviewers say strong conclusions are hard. Few studies ran past six months, so longer-term effects are unknown. An earlier Cochrane review of 36 trials reached a similar verdict: the evidence was inconsistent and unreliable, and three of the four most recent trials found no difference from placebo. NCCIH likewise describes a possible modest benefit, especially at relatively high doses, but inconsistent evidence.
A 2025 meta-analysis pooled four placebo-controlled trials (782 people with mild dementia) of 240 mg a day of the standardized extract. It reported better scores for cognition, global assessment, daily activities and quality of life, with similar side-effect rates to placebo. Treat it with care. It covers one extract, it selected subgroups of patients from trials, and one author lists a company affiliation. For how pooled analyses work, see our guide to meta-analyses and systematic reviews.
Other thinking problems
For people worried about their memory but without a diagnosis, Cochrane rated the evidence very uncertain (three studies, 597 people), and one three-month study found side effects may be higher with ginkgo. For cognitive problems linked to multiple sclerosis, two studies (164 people) found probably little or no effect at three months.
Anxiety, stroke recovery, tinnitus, blood pressure and others
NCCIH says a small amount of evidence suggests a benefit for anxiety, PMS, schizophrenia and vertigo, but it is not conclusive. Ginkgo might help stroke rehabilitation. Research suggests it does not help prevent heart disease, treat high blood pressure, or relieve tinnitus or multiple sclerosis symptoms.
A 2024 meta-analysis of 12 records found that adding a ginkgo leaf extract and dipyridamole combination to the drug edaravone gave better results than edaravone alone in acute stroke. Because it is a combination product, it cannot show what ginkgo itself did. The authors cite few studies and possible publication bias. A 2026 review of traumatic brain injury (65 studies, 23 of them clinical) found potential improvements but concluded that clinical data are insufficient for routine use. A 2026 review of retinal protection covered only laboratory and animal experiments and called for human trials.
What doses did researchers use?
This describes what studies used and is not a recommendation. The mild dementia analysis used 240 mg a day of one standardized extract. The GEM trial gave a reported “more than 120 milligrams” twice a day. Doses differ by condition and extract, and the reviews describe optimal dosing as still unsettled. The 2026 traumatic brain injury review calls for trials to optimize dosing.
Is it safe? Side effects and interactions
NCCIH says ginkgo leaf extracts are likely safe for most adults in moderate amounts by mouth, and have been used safely in studies lasting up to 6 years. The most common side effects are dizziness, stomach and bowel symptoms, and headache. A Chicago Sun-Times piece from a nutrition newsletter adds upset stomach and constipation.
| Concern | What the sources say |
|---|---|
| Bleeding | NCCIH says ginkgo may raise bleeding risk in people taking anticoagulants such as warfarin. The traumatic brain injury review reports bleeding events, especially with anticoagulants or NSAID pain relievers. |
| Other drugs | NCCIH says it may interact with other drugs. The newsletter lists blood thinners, diabetes drugs, anticonvulsants, statins and antidepressants. |
| Seeds and crude plant | Fresh seeds are toxic. Serious side effects have occurred with roasted seeds and the crude plant. |
| Pregnancy and breastfeeding | May be unsafe in pregnancy and might cause early labor or extra bleeding near delivery. Little is known about breastfeeding. |
| Stroke | The trial in people 85 and older noted an increased stroke risk in the ginkgo group. |
| Extract quality | A 2026 review says ginkgolic acids and another compound can cause toxic effects, so quality control matters. |
What happens if you take it every day?
In trials, daily use for up to 6 years was tolerated by most participants, per NCCIH. In Cochrane’s dementia and mild cognitive impairment trials, side effects were about the same as with placebo for up to 12 months. Nothing in these sources tells you how daily use affects any one person, which is why medicine interactions matter more than the length of use.
Why isn’t ginkgo FDA approved?
Dietary supplements do not need approval from the U.S. Food and Drug Administration before they are sold. NCCIH says the rules for supplements are less strict than for drugs, and that manufacturers are responsible for evaluating the safety and labeling of their products. The FDA can act if safety concerns arise. Ginkgo is sold under those supplement rules, and it has not been shown to work for any condition tested.
Who should talk to a clinician first?
- Anyone taking an anticoagulant, an NSAID, or a diabetes, seizure, statin or antidepressant medicine. A pharmacist or doctor can check for interactions.
- Anyone pregnant, near delivery or breastfeeding.
- Anyone with a bleeding concern or a procedure planned, since bleeding is the main interaction worry.
- Anyone who has had a stroke, given the stroke-risk note in the 85-and-older trial.
- Anyone taking ginkgo for memory loss. A clinician can assess the cause and the options, and nothing here suggests changing a prescribed medicine for ginkgo.
Questions such as whether ginkgo affects the kidneys, whether coffee matters, and what time of day to take it are not addressed by these official and review sources. A pharmacist can answer them for your own medicines and conditions. The label directions on a specific product are the other place to check.
What is still unknown?
- Whether the small dementia benefit is real, since results across trials vary widely.
- Effects beyond six months in dementia.
- The best dose and extract.
- Benefits in healthy adults, where much of the research is low quality.
- Human effects for eye, brain-injury and other uses studied mostly in animals or small trials.
How do you read a label that lists ginkgo?
- Form: Look for a leaf extract. Trials used leaf extracts, and seeds and crude plant material are the toxic forms.
- Standardization: Many trials used a specific standardized extract. A label that says only “ginkgo” does not tell you it matches what was studied.
- Amount: Compare the milligrams per serving and servings per day with the study doses above.
- Proprietary blends: If ginkgo sits in a blend that lists only a combined weight, you cannot tell how much ginkgo you are getting, so you cannot compare it with any study.
- Claims: “Brain health” wording is marketing. Our guide on ingredient evidence versus marketing claims explains the gap.
Before you order
- Ask your pharmacist whether ginkgo interacts with anything you take.
- Confirm the product is a leaf extract and shows the amount per serving.
- Ask the maker for the extract’s standardization and quality testing.
By ClinicalStudyConnect.com Research Desk
This article is for general information purposes only and does not constitute medical advice. Consult your doctor or qualified healthcare provider before making changes to your health routine.