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Tradition

Dosing

Adults (18 years and older)

80-240 milligrams of a 50:1 standardized leaf extract taken daily by mouth in two to three divided doses has been used and studied (standardized to 24% to 25% ginkgo flavone glycosides and 6% terpine lactones). Other forms used include tea (bags usually contain 30 milligrams of extract), 3 to 6 milliliters of 40 milligrams per milliliter extract daily in three divided doses, and "fortified" foods. Ginkgo seeds are potentially toxic and should be avoided. The German ginkgo product Tebonin®, given through veins (IV), was removed from the German market due to significant side effects.

Children (younger than 18 years)

There is not enough scientific evidence to recommend use of ginkgo in children.

Safety

Allergies

Allergy/hypersensitivity to Ginkgo biloba or members of the Ginkgoaceae family may occur. A severe reaction called Stevens-Johnson syndrome, which includes skin blistering and sloughing-off, has been reported with use of a combination product. There may be cross-sensitivity to ginkgo in people allergic to urusiols (mango rind, sumac, poison ivy, poison oak, cashews), and an allergic cross-reaction has been reported in a person allergic to poison ivy.

If administered into a vein (IV), ginkgo may cause a skin allergy, blood vessel irritation and damage. Ginkgo fruit or pulp has caused strong allergic reactions after skin contact, and severe skin reactions and intestinal spasms have occurred after direct contact with fleshy fruit pulp.

Side Effects and Warnings

Overall, ginkgo leaf extract (used in most commercial products) appears to be well tolerated in most healthy adults at recommended doses for up to six months. Minor symptoms including headache, nausea, and intestinal complaints have been reported.

Bleeding has been associated with the use of ginkgo taken by mouth, and caution is advised in patients with bleeding disorders or taking drugs/herbs/supplements that may increase the risk of bleeding. Dosing adjustments may be necessary. Ginkgo should be stopped prior to some surgical or dental procedures. Reports of bleeding range from nose bleeds to life-threatening bleeding in several case reports. In some of these reports, ginkgo has been used with other agents that may also cause bleeding.

Eating the seeds is potentially deadly, due to risk of tonic-clonic seizures and loss of consciousness.

Based on human study, ginkgo may theoretically affect insulin and blood sugar levels. Caution is advised in patients with diabetes or hypoglycemia, and in those taking drugs, herbs, or supplements that affect blood sugar. Serum glucose levels may need to be monitored by a healthcare professional, and medication adjustments may be necessary.

There have been uncommon reports of headache, dizziness, stomach upset, nausea, diarrhea, vomiting, muscle weakness, loss of muscle tone, restlessness, heart racing, rash, and irritation around the mouth with the use of ginkgo. There is a case report of "coma" in an elderly Alzheimer's patient taking trazodone and ginkgo, although it is not clear that ginkgo was the cause. Based on laboratory and human research, ginkgo may decrease blood pressure, although there is one report of ginkgo possibly raising blood pressure in a person taking a thiazide diuretic ("water pill"). Based on theory, high concentrations of ginkgo may reduce male and female fertility. Contamination with the drug colchicine has been found in commercial preparations of Ginkgo biloba.

Ginkgo may affect the outcome of electroconsulvie therapy (ECT). Adverse effects on the eyes have also been reported.

Another study reported vomiting and convulsions from large quantities of MPN (4-O-methylpyridoxine), which is contained in Ginkgo biloba seeds.

Pregnancy and Breastfeeding

Use of ginkgo is not recommended during pregnancy and breastfeeding due to lack of reliable scientific study in this area. The risk of bleeding associated with ginkgo may be dangerous during pregnancy.