Side Effects of Ginkgo Biloba | Safety Guide

Ginkgo Biloba is one of the most widely used herbal supplements in the world, valued for its potential to support memory, circulation, and focus. With a medicinal history stretching back to approximately 2800 BC in Chinese writings, it has accumulated a substantial body of modern research — including data on its safety profile.

Understanding the side effects of Ginkgo Biloba is essential for anyone considering this supplement, particularly those who take other medications or have underlying health conditions. While standardized Ginkgo Biloba leaf extract is generally considered safe and well-tolerated in clinical studies, there are specific risks and interactions that warrant careful attention.

This guide covers the known adverse effects, drug interactions, and special population warnings drawn from systematic reviews, randomized controlled trials, and institutional safety assessments.

In systematic review data, overall adverse events and serious adverse events associated with standardized Ginkgo Biloba extract were at the same level as placebo. In subgroups of Alzheimer's disease patients, fewer adverse events were observed in the ginkgo group, along with fewer incidences of vertigo, tinnitus, angina pectoris, and headache compared to placebo.

The most commonly reported mild side effects of Ginkgo Biloba include:

• Gastrointestinal upset
• Headaches
• Dizziness

These reactions are generally infrequent and tend to be transient. In the tinnitus trial comparing EGb 761 with pentoxifylline, the incidence of adverse events was lower in the ginkgo group.

The interaction between Ginkgo Biloba and anticoagulant or antiplatelet drugs is one of the most clinically discussed side effects of Ginkgo Biloba. Because ginkgo contains ginkgolides — particularly ginkgolide B, the most potent known naturally occurring inhibitor of platelet-activating factor — there is a theoretical and partially demonstrated concern about increased bleeding risk.

The evidence is notably mixed. A systematic review and meta-analysis of 18 randomized controlled trials found that ginkgo significantly reduced blood viscosity but had no effects on ADP-induced platelet aggregation, fibrinogen concentration, activated partial thromboplastin time, or prothrombin time.

However, institutional bodies flag this interaction as clinically relevant. The NCCIH notes that taking Ginkgo Biloba with warfarin is associated with increased risk for major bleeding events compared to warfarin alone. A large hospital-based observational study of 2,647 prescriptions found that Ginkgo Biloba extract frequently interacts with antiplatelets, anticoagulants, and nonsteroidal anti-inflammatory drugs, with clopidogrel and aspirin exhibiting the highest interaction prevalence rates at 2.61% each. Significant correlations were found between Ginkgo Biloba extract drug interactions and bleeding risk (OR: 1.08, p < 0.001) and abnormal coagulation (OR: 1.49, p < 0.001).

Ginkgo Biloba may also interact with efavirenz, a non-nucleoside reverse transcriptase inhibitor. This interaction relates to ginkgo's induction of cytochrome P450 enzymes, particularly CYP3A4, which can reduce plasma concentrations of co-administered drugs that rely on this metabolic pathway. Concomitant use of Ginkgo Biloba preparations and efavirenz is not recommended.

Ginkgolic Acid Toxicity

Ginkgolic acids are structurally similar to the irritants in poison ivy and are responsible for some of the toxic side effects of Ginkgo Biloba, including gastrointestinal disturbances, headaches, skin irritation, dermatitis, and edema. This is why product standardization matters: the pharmaceutical-grade extract EGb 761 contains less than 5 parts per million (ppm) of ginkgolic acids, and both the European and US Pharmacopoeias set strict limits on this compound.

Choosing a standardized Ginkgo Biloba extract — rather than raw leaf preparations or unstandardized products — substantially reduces exposure to these irritants.

Ginkgo Seed Toxicity

It is critical to distinguish between ginkgo leaf extract supplements and ginkgo seeds. Fresh ginkgo seeds are toxic when consumed orally, and serious side effects — including seizures and death — have occurred in people who consumed raw ginkgo seeds or the crude ginkgo plant. Roasted ginkgo seeds can also cause adverse reactions. The neurotoxic compound primarily responsible for seizures is ginkgotoxin (4-O-methylpyridoxine), which acts as an antagonist of vitamin B6 and can precipitate seizures, particularly in children and with large quantities. This is a distinct hazard from standardized ginkgo leaf extract supplements.

Pregnancy and Breastfeeding

Ginkgo may be unsafe for use during pregnancy. It might cause early labor or extra bleeding during delivery if used near that time. Little is known about whether it is safe to use ginkgo while breastfeeding. Women who are pregnant or nursing should consult a healthcare professional before use.

Because of the wide variation of ginkgo products on the market, product quality has a direct impact on safety. Even two high-quality extracts complying with the same pharmacopoeia guideline can be disparate in nature — for instance, the allowable range of 22%–27% flavone glycosides means one extract could contain almost 23% more of that compound class than another.

This variability between commercial products has important implications for both efficacy and safety. A product that is not properly standardized may contain higher levels of ginkgolic acids, which are directly responsible for gastrointestinal, dermatological, and other adverse effects.

The European Pharmacopoeia requires that dried Ginkgo Biloba leaf extract be adjusted to 22.0%–27.0% ginkgo flavonoids and 5.4%–6.6% terpene lactones, while containing less than 5 ppm ginkgolic acids. This product is standardized under strict European quality standards — comparable to over-the-counter drug standards in the United States — and provides optimal levels of naturally occurring flavonglycosides and terpene lactones in each 120 mg capsule of standardized Ginkgo Biloba leaf extract in a 50:1 concentrate.

Take one (1) vegetarian capsule, two (2) times daily with meals.

This product is gluten free, dairy free, soy free, and grain free. Individuals who are taking anticoagulant or antiplatelet medications, those who are pregnant or breastfeeding, and anyone scheduled for surgery should consult a healthcare professional before use to discuss potential side effects of Ginkgo Biloba in their specific situation.