Safety
Likely Safe …
when used orally and appropriately. Standardized ginkgo leaf extracts have been used safely in trials lasting for several weeks up to 6 years. Also, a specific combination product (Memo, Pharco Pharmaceuticals, Alexandria, Egypt), which contains natural lyophilized royal jelly 750 mg, standardized ginkgo leaf extract 120 mg (containing 24% flavonoids glycosides and 6% terpenoids), and standardized Panax ginseng root extract 150 mg (containing 40% to 80% ginsenosides) has been used safely for up to 4 weeks.
However, there is concern about toxic and carcinogenic effects seen in animals exposed to a ginkgo leaf extract containing 31.2% flavonoids, 15.4% terpenoids, and 10.45 ppm ginkgolic acid, in doses of 100 to 2000 mg/kg five times per week for 2 years. Hepatic, thyroid, gastric and nasal toxicities were seen, including thyroid and liver cancers, rates of which were increased in a dose-dependent manner. However, the clinical relevance of this data for humans, using typical doses, is unclear. The content of the extract used is not identical to that commonly used in supplement products, and the doses studied are much higher than those typically used by humans. A single dose of 50 mg/kg in rats is estimated to be equivalent to a single dose of about 240 mg in humans.
Possibly Safe …
when used intravenously, short-term. A standardized ginkgo leaf extract called EGb 761 ONC has been safely administered intravenously for up to 10 days.
Possibly Unsafe …
When the roasted seed or crude ginkgo plant is used orally. Consuming more than 10 roasted seeds per day can cause difficulty breathing, weak pulse, seizures, loss of consciousness, and shock. Crude ginkgo plant parts can exceed concentrations of 5 ppm of the toxic ginkgolic acid constituents and can cause severe allergic reactions.
Likely Unsafe …
when the fresh ginkgo seed is used orally. Fresh seeds are toxic and potentially deadly.
There is insufficient reliable information available about the safety of ginkgo when used topically.
Children:
Possibly Safe …
when used orally and appropriately, short-term. A specific ginkgo dried extract (Ginko T.D., Tolidaru Pharmaceuticals), has been safely used in doses of 80-120 mg daily for 6 weeks in children aged 6-14 years. Another specific combination product containing ginkgo leaf extract and American ginseng extract (AD-FX, CV Technologies, Canada) has also been safely used in children aged 3-17 years for up to 4 weeks.
Likely Unsafe …
when ginkgo seed is used orally. The fresh seeds have caused seizures and death in children.
Pregnancy:
Possibly Unsafe …
when used orally. There is concern that ginkgo might have labor-inducing and hormonal effects. There is also concern that the antiplatelet effects of ginkgo could prolong bleeding time if taken around the time of labor and delivery. Theoretically, ginkgo might adversely affect pregnancy outcome; avoid using during pregnancy.
Lactation:
Insufficient reliable information available; avoid using.