An Introduction to a Popular Herbal Supplement
Ginkgo biloba, derived from one of the world's oldest living tree species, is a popular herbal supplement often used to improve memory, concentration, and blood flow [1.2.3, 1.2.5]. Standardized extracts of the ginkgo leaf, such as EGb 761, are the most studied forms and are generally considered safe for most adults in moderate doses, typically 120 to 240 mg per day [1.5.1, 1.5.5]. However, despite its widespread use, Ginkgo biloba is not without significant drawbacks and potential dangers. It is not regulated by the FDA as a drug, meaning its safety and efficacy are not subject to the same rigorous standards as prescription medications [1.2.3, 1.5.9]. Before starting this supplement, it's essential to be fully aware of its potential disadvantages, which can impact everyone from the average user to individuals with specific health conditions.
The Primary Disadvantage: Increased Bleeding Risk
One of the most serious disadvantages associated with Ginkgo biloba is its effect on blood clotting [1.2.9]. Ginkgo has antiplatelet properties, meaning it can slow down the blood's ability to form clots [1.4.8]. This effect significantly increases the risk of bleeding, which can manifest in various ways, from easy bruising and nosebleeds to more severe internal bleeding in the eye or brain [1.2.1, 1.2.7]. This risk is not just theoretical; there are numerous reports of bleeding problems associated with ginkgo use [1.2.7, 1.6.5].
This anticoagulant effect becomes particularly dangerous when ginkgo is taken alongside other medications that also thin the blood. This includes:
- Prescription anticoagulants: Warfarin (Coumadin), heparin, and enoxaparin [1.3.1, 1.3.6].
- Antiplatelet drugs: Clopidogrel [1.3.2].
- Over-the-counter painkillers: Aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen (Advil, Motrin) and naproxen (Aleve) [1.3.3, 1.3.4].
Due to this elevated bleeding risk, individuals with bleeding disorders should not use ginkgo [1.5.6]. Furthermore, it is strongly recommended to stop taking ginkgo at least two weeks before any scheduled surgery to prevent excessive bleeding during and after the procedure [1.2.3, 1.5.6].
Significant Drug Interactions Beyond Blood Thinners
Ginkgo's disadvantages extend to a wide range of drug interactions that can either reduce the effectiveness of medications or increase the risk of toxic side effects. It can affect how the liver breaks down certain drugs, potentially altering their levels in the bloodstream [1.2.2, 1.5.3].
Key interactions include:
- Antidepressants: Taking ginkgo with certain antidepressants, such as fluoxetine (Prozac) and trazodone, may decrease their effectiveness or, in some cases, lead to a rare but serious condition called serotonin syndrome [1.3.3, 1.2.9].
- Anti-seizure Medications: Ginkgo may lower the seizure threshold and interfere with the efficacy of anticonvulsant drugs [1.3.3, 1.4.7]. There are reports of ginkgo causing seizures even in individuals with no history of them [1.4.7]. People with epilepsy should not use ginkgo [1.5.6].
- Diabetes Medications: Ginkgo might interfere with the management of diabetes by altering the response to these medicines. Patients with diabetes should monitor their blood sugar closely if they choose to take ginkgo [1.4.1, 1.5.6].
- Blood Pressure Medications: Because ginkgo can cause vasodilation and lower blood pressure, combining it with antihypertensive drugs could cause blood pressure to drop too low [1.2.5, 1.2.9].
- Other Medications: Interactions have also been noted with alprazolam (Xanax), certain statins like simvastatin (Zocor), and omeprazole [1.3.3, 1.3.2].
Common Side Effects and Allergic Reactions
Even when taken on its own, Ginkgo biloba can cause a variety of undesirable side effects. While often mild, they can be disruptive. These include:
- Headache [1.2.4]
- Dizziness [1.2.4]
- Heart palpitations [1.2.2]
- Stomach upset, nausea, and diarrhea [1.2.3, 1.2.4]
- Constipation [1.2.2]
Allergic reactions are another significant concern. Some people may experience skin rashes or more severe reactions [1.2.6]. Notably, ginkgolic acids found in the ginkgo tree are structurally similar to allergens in poison ivy, poison oak, mango rind, and cashew shell oil. This can lead to cross-reactivity in sensitive individuals [1.5.6, 1.6.6]. In rare cases, severe skin reactions like Stevens-Johnson syndrome have been reported after ingesting ginkgo extract [1.6.8, 1.6.9].
Risk Profile Comparison: Ginkgo Leaf Extract vs. Other Ginkgo Parts
It is crucial to distinguish between the standardized ginkgo leaf extract used in supplements and other parts of the plant, which carry different and more severe risks.
| Part of Plant | Primary Use/Form | Key Disadvantages & Risks |
|---|---|---|
| Standardized Leaf Extract (e.g., EGb 761) | Supplements (capsules, tablets) [1.2.2] | Increased bleeding risk, drug interactions, headache, dizziness, stomach upset, allergic skin reactions [1.2.4, 1.3.3]. Generally safe at recommended doses (120-240mg/day) [1.5.1]. |
| Raw/Fresh Ginkgo Seeds | Not for consumption | Highly toxic and poisonous. Can cause seizures and death, even in small amounts. Considered unsafe to eat [1.2.3, 1.4.2, 1.5.6]. |
| Roasted Ginkgo Seeds | Edible in some cultures | Possibly unsafe. Eating more than 10 roasted seeds daily can cause serious side effects, including seizures [1.5.6]. Contain ginkgotoxin [1.5.4]. |
| Crude/Untreated Ginkgo Plant/Fruit | Not for consumption | The fleshy fruit pulp can cause allergic contact dermatitis similar to poison ivy due to ginkgolic acids [1.5.4, 1.6.6]. |
Risks for Specific Populations
Certain groups of people face heightened risks and should avoid using Ginkgo biloba altogether.
- Pregnant and Breastfeeding Women: Ginkgo is considered likely unsafe during pregnancy. It may induce early labor or cause extra bleeding during delivery [1.4.2, 1.4.5]. Its safety during breastfeeding is unknown and should be avoided [1.4.8].
- People with Epilepsy: As mentioned, ginkgo can interfere with seizure medications and may cause seizures on its own. It should not be used by individuals with a history of seizures [1.4.1, 1.5.6].
- Children: Ginkgo leaf extract is not recommended for children due to a lack of safety data [1.5.1]. Raw ginkgo seeds are especially dangerous and have caused seizures and death in children [1.5.6].
- Those with Fertility Problems: Some evidence suggests ginkgo use might interfere with getting pregnant [1.5.6].
Conclusion
While Ginkgo biloba is a widely available supplement with purported cognitive and circulatory benefits, its disadvantages are significant and cannot be overlooked. The primary concerns are a substantially increased risk of bleeding, a long list of potentially dangerous drug interactions, and a profile of side effects ranging from mild to severe. Specific populations, including pregnant women and individuals with epilepsy or bleeding disorders, should avoid it entirely. The toxicity of non-extract parts of the plant, especially the seeds, adds another layer of risk. Given these potential dangers, it is imperative to consult with a healthcare professional before considering the use of Ginkgo biloba. This step ensures a thorough review of your health conditions and current medications to prevent adverse outcomes.
For more authoritative information on herb-drug interactions, you can visit the National Center for Complementary and Integrative Health (NCCIH): https://www.nccih.nih.gov/health/providers/digest/herb-drug-interactions-science [1.3.6]
