Ginkgo Biloba Benefits: What the GEM Trial Found and Safety

Ginkgo biloba benefits are mostly a story of high hopes and disappointing trials. Ginkgo leaf extract is one of the most widely sold herbal supplements in the world, marketed for memory, circulation and ringing in the ears. Yet the National Center for Complementary and Integrative Health (NCCIH) says there is no conclusive evidence that ginkgo helps any health condition, and the largest trial, which followed more than 3,000 older adults for about six years, found no reduction in dementia. Ginkgo also carries real safety questions, above all bleeding risk with blood thinners. Here is what the research shows, who should be careful and what to look for on a label.

Peptide Labs sells no ginkgo biloba products, and this article does not recommend any product. It is general information, not medical advice.

What is ginkgo biloba?

Ginkgo is a tree so ancient that it is often called a living fossil; NCCIH describes it as the last remaining species of a primitive plant family. Its seeds and leaves have a long history in traditional Chinese medicine. Today the most common form is an extract of the leaves, sold as capsules, tablets, liquid extracts and teas. Leaf extracts are complex mixtures; researchers at the FDA’s National Center for Toxicological Research describe flavonol glycosides and terpene lactones as major components. Some large trials used a standardized leaf extract known as EGb 761.

NCCIH lists a long range of uses ginkgo is promoted for, including anxiety, heart disease, memory problems and dementia, diabetes, premenstrual syndrome, schizophrenia and tinnitus, along with claims of sharper thinking in healthy people. The question is how well those claims hold up.

Ginkgo biloba benefits: what the research shows

NCCIH’s summary is blunt: there have been many studies, but ginkgo has not been shown to be effective for any of the conditions it has been studied for. The table gives the short version, and the sections below explain the main trials.

Ginkgo biloba for memory: the GEM study

The Ginkgo Evaluation of Memory (GEM) study, funded by NCCIH and the National Institute on Aging, is the trial most people mean when they talk about ginkgo and the brain. Published in JAMA in 2008, it randomly assigned 3,069 community volunteers aged 75 or older, most with normal thinking and 482 with mild cognitive impairment, to ginkgo extract or placebo at five US academic centers. After a median of 6.1 years, 277 people in the ginkgo group and 246 in the placebo group had developed dementia, a difference that was not statistically significant. Ginkgo also did not slow progression to dementia in people who started with mild cognitive impairment.

A follow-up analysis in JAMA in 2009 looked at thinking skills themselves. Rates of decline in memory, attention, visual-spatial skills, language and executive function were the same in both groups. In France, the GuidAge trial followed 2,854 adults aged 70 or older with memory complaints for five years. It found no significant reduction in progression to Alzheimer’s disease with a standardized ginkgo extract; that trial was funded by the drug company Ipsen.

NCCIH notes that ginkgo may have a modest effect on symptoms in people who already have dementia, particularly at higher intakes, but the evidence is inconsistent, and it is unclear whether ginkgo helps milder memory problems. Memory changes deserve a medical evaluation, because many causes, such as thyroid problems, low vitamin B12 or medicine side effects, can be identified and addressed.

Tinnitus, circulation and other claims

A 2022 Cochrane review of 12 trials with 1,915 participants found that ginkgo may have little to no effect on tinnitus severity compared with placebo, and rated the evidence very low certainty because many studies had a high or unclear risk of bias. NCCIH adds that research suggests ginkgo does not help prevent heart disease, lower high blood pressure or relieve tinnitus or multiple sclerosis symptoms, and Memorial Sloan Kettering Cancer Center (MSKCC) reports that GEM found no benefit for cardiovascular events or deaths. A small amount of evidence points to possible benefits for anxiety, premenstrual syndrome, schizophrenia and vertigo, and for stroke rehabilitation, but NCCIH calls the overall evidence not conclusive. If you are weighing herbs for energy or focus, our ginseng guide covers a different plant with its own mixed evidence.

Ginkgo biloba side effects

NCCIH says ginkgo leaf extracts are likely safe for most adults when taken by mouth in moderate amounts, and they were used in research lasting as long as six years. The most common side effects are dizziness, digestive symptoms and headache. MSKCC also lists case reports of low blood sodium, with confusion, headache and fatigue that resolved after people stopped ginkgo, and of skin reactions.

Bleeding risk and blood thinners

The most important caution is bleeding. NCCIH warns that ginkgo may increase the risk of bleeding in people taking anticoagulant drugs such as warfarin. MSKCC describes case reports of spontaneous bleeding, including bleeding inside the skull and in the eye, a study in healthy volunteers in which some had prolonged bleeding time when ginkgo was combined with antiplatelet drugs, and adverse event reports suggesting additive effects with nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen.

• Blood thinners and antiplatelet drugs: talk with your prescriber before combining them with ginkgo.
• Surgery and dental work: tell your surgical team about ginkgo and every other supplement you use well ahead of time.
• Other supplements: some, such as nattokinase, raise similar questions; see our guides to nattokinase and turmeric side effects before stacking them.

Seizures and other drug interactions

MSKCC lists several other interactions to raise with a healthcare provider. Ginkgo has been linked to seizures in people with a seizure history or who take medicines that lower the seizure threshold, such as prochlorperazine. Case reports suggest it may make the HIV drug efavirenz less effective, and a study in healthy people found lower blood levels of midazolam. MSKCC also mentions insulin, and a single case report of coma in a person with Alzheimer’s disease who took ginkgo with trazodone. Laboratory studies show ginkgo can affect liver enzymes that process many drugs, but MSKCC calls the data conflicting and the clinical importance unclear. A pharmacist can check your full list.

Pregnancy and breastfeeding

NCCIH says ginkgo may be unsafe during pregnancy because it might cause early labor or extra bleeding during delivery, and little is known about its safety while breastfeeding.

Ginkgo seeds are not the same as leaf extract

Supplements use the leaves, but ginkgo seeds, often called ginkgo nuts, are eaten in parts of Asia. NCCIH warns that fresh seeds are toxic, and serious effects have followed eating roasted seeds or the crude plant. A 2019 review explains that eating too many seeds can cause vomiting and convulsions. The main toxin, 4′-O-methylpyridoxine, sometimes called ginkgotoxin, works against vitamin B6, and poisonings have been reported in Asia, North America and Europe. Seeds also contain ginkgolic acids, which can cause allergic reactions. Never use raw seeds or crude ginkgo plant material as a supplement.

The rodent cancer finding

In two-year studies by the National Toxicology Program, a ginkgo leaf extract given to mice produced what the program called clear evidence of cancer-causing activity in the liver. Based in part on that work, the International Agency for Research on Cancer classified ginkgo leaf extract as possibly carcinogenic to humans (Group 2B), a category for limited evidence. FDA scientists who reviewed the findings noted that large human trials have not shown cancer benefits, and MSKCC says secondary GEM data do not support using ginkgo to lower cancer risk. Animal results at very high exposures do not translate directly to people, but they are one more reason not to assume a plant extract is harmless.

Reading a ginkgo label

Ginkgo products vary in plant part, extract type and standardization, and the US does not approve supplements before they are sold. Look for a product that names the leaf extract, lists its standardization if it claims one and carries an independent seal; our guide to third-party tested supplements explains what those seals check. Herbal blends marketed for focus or energy may hide ginkgo among many ingredients, so read the full Supplement Facts panel. Echinacea, another popular herb, has similar label problems; see our echinacea guide.

Frequently Asked Questions

Questions about a label? Contact us or read our Buyer’s Guide. Follow the label and ask a healthcare provider before starting any supplement, especially if you take medicines or are pregnant. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Last reviewed October 2026.

Related guides: Nattokinase: Benefits, Side Effects and Bleeding Risks, Turmeric Side Effects: Liver Injury, Interactions and Turmeric vs Curcumin, Third Party Tested Supplements: What USP, NSF and Other Seals Mean.