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Adverse Side Effects, Toxicity and Contraindications

Ginkgo Biloba Extract is considered to be relatively safe. Extremely high doses have been given to animals for extended periods without evidence of toxicity or untoward side effects. Of the nearly 10,000 patients followed in various ginkgo trials thus far, reports of side effects have been few, and include gastrointestinal discomfort, headaches, dizziness, and allergic skin reactions. However, Ginkgo Biloba Extract is a proven anticoagulant and through this action, it may increase the risk of internal bleeding in the brain and other cranial regions. To date, there have been two case reports linking the use of Ginkgo Biloba to bleeding disorders, including a patient presenting with a subdural hematoma (bleeding in the skull) and another with hyphema (spontaneous bleeding in the iris chamber). As such, ginkgo should not be used by those with known bleeding disorders (e.g., hemophilia), or during the period before or immediately after surgery, and prior to labor or after delivery. 29, 31 32, 38 To avoid possible dizziness some authorities suggest that one should limit the single dose of Ginko Biloba Extract to 40 mg tablets. To avoid insomnia produced by the vasodilation effect of Ginko Biloba Extract, do not take it at night. It is best to take it in divided doses in the morning, at lunch, mid afternoon and/or early evening.

Drug-Nutrient Interactions

  1. Anticoagulants – Ginkgo is known to potentiate the effects of anticoagulant drugs and bleeding disorders in the brain and cranial vault have been reported in humans. As such, Ginkgo should not be taken concurrently with anticoagulants, including aspirin, coumadin, warfarin, plavix, ticlid, trental etc. 32,33,34,35,38
  2. Non Steroidal Anti-Inflammatory Drugs (NSIADs) – Ginkgo may increase the risk of bleeding disorders associated with the use of NSAIDs, and thus should not be taken concurrently with these medications. 36
  3. Monoamine Oxidase Inhibitors ( MAO- inhibitors) – Ginkgo may potentiate the action of MAO-inhibitor anti-depressant drugs, and thus should not be taken concurrently with these medications