Ginkgo Biloba - Allergic Precautions and Contraindications To Use

Allergic Precautions and Contraindications To Use

People taking pharmaceutical blood thinners such as warfarin or coumadin should consult with their doctors before taking Ginkgo biloba extracts, as it acts as an anticoagulant.

The presence of amentoflavone in G. biloba leaves would indicate a potential for interactions with many medications through the strong inhibition of CYP3A4 and CYP2C9; however, no empirical evidence supports this. Further, at recommended doses, studies have shown, "ultiple-dose administration of Ginkgo biloba did not affect cytochrome P-450 2D6 or 3A4 activity in normal volunteers." The concentration of amentoflavone found even in commercial ginkgo extracts possibly is too low to be pharmacologically active.

Ginkgo biloba leaves and sarcotesta also contain ginkgolic acids, which are highly allergenic, long-chain alkylphenols such as bilobol (a substance related to anacardic acid from cashew nut shells and urushiols present in poison ivy and other Toxicodendron spp.) Individuals with a history of strong allergic reactions to poison ivy, mangoes, cashews and other alkylphenol-producing plants are more likely to experience an adverse reaction when consuming ginkgo-containing pills, combinations, or extracts. The level of these allergens in standardized pharmaceutical preparations from Ginkgo biloba was restricted to 5 ppm by the Commission E of the former Federal German Health Authority.