Ginkgo biloba has been used medicinally for thousands of years. Today, it is one of the top-selling herbs in the United States.
Ginkgo is used for the treatment of numerous conditions, many of which are under scientific investigation. Available evidence demonstrates ginkgo’s efficacy in the management of intermittent claudication, Alzheimer’s/multi-infarct dementia, and “cerebral insufficiency” (a syndrome thought to be secondary to atherosclerotic disease, characterized by impaired concentration, confusion, decreased physical performance, fatigue, headache, dizziness, depression, and anxiety).
Although not definitive, there is promising early evidence favoring the use of ginkgo for memory enhancement in healthy subjects, altitude (mountain) sickness, symptoms of premenstrual syndrome (PMS), age-related eye disorders, and the reduction of chemotherapy-induced end-organ vascular damage.
The herb is generally well tolerated, but due to multiple case reports of bleeding, it should be used cautiously in patients on anticoagulant therapy and those with known blood clotting disorders, or prior to some surgical or dental procedures.
Usage and Dosing
NB! The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.
Adults (over 18 years old)
Traditional recommendations include ginkgo products containing 24% flavoglycosides (also called flavone glycosides or flavones) and 6% terpenes: 80-240 milligrams of a 50:1 standardized leaf extract daily, or 3-6 milliliters of a 40 milligram per milliliter liquid extract in 2-3 divided doses, or 30-40 milligrams of extract in a tea bag, prepared as a tea, for at least 4-6 weeks. There is a lack of evidence in support of the clinical benefit of small concentrations of ginkgo found in fortified foods. All doses above are oral unless otherwise stated. Beneficial effects may take 4-6 weeks to appear. Ginkgo seeds are potentially toxic and should be avoided. The intravenous ginkgo product Tebonin®, which was available in Germany, was removed from the German market due to significant adverse effects.
40-240 milligrams of extract, tincture, or powder has been taken by mouth daily, divided into two or three doses. Beneficial effects may take 4-6 weeks to appear. Patients have also been treated with intravenous ginkgo preparations: 0.7 milligrams of intravenous extract per minute for 120 minutes; 100 milligrams of ginkgo in 500 cubic centimeters of normal saline, administered twice daily; 20 milliliters of ginkgo in 250 milliliters of normal saline daily for four weeks; and 200 milligrams of EGb 761 infusion for 10 days, followed by a twice-daily oral dose of 80 milligrams for 12 weeks.
Children (under 18 years old)
Dyslexia : A single 80 milligram dose of EGb 761 daily for an average of 34.4 days.
NB! There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.
Allergy or 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 urushiols (mango rind, poison sumac, poison ivy, poison oak, cashews), and an allergic cross-reaction has been reported in a person allergic to poison ivy.
Side Effects and Warnings
- Overall, ginkgo leaf extract (used in most commercial products) appears to be well tolerated in most healthy adults at suggested doses for up to six months. Minor symptoms, including headache, nausea, and intestinal complaints have been reported.
- Ginkgo may be unsafe in children.
- Ginkgo may increase the risk of stroke.
- 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 dizziness, stomach upset, diarrhea, vomiting, muscle weakness, loss of muscle tone, restlessness, racing heart, 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.
- 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”).
- High concentrations of ginkgo may reduce male and female fertility.
- Contamination with the drug colchicine has been found in commercial preparations of Ginkgo biloba .
- Bleeding has been associated with the use of ginkgo taken by mouth, and caution is advised in patients with bleeding disorders or those taking drugs, herbs, or 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 fresh ginkgo seeds is potentially deadly, due to the risk of tonic-clonic seizures and loss of consciousness.
- Ginkgo may affect the outcome of electroconvulsive therapy (ECT). Adverse effects on the eyes have also been reported.
Pregnancy and Breastfeeding
Use of ginkgo is not suggested during pregnancy and breastfeeding, due to the lack of reliable scientific study in this area. The risk of bleeding associated with ginkgo may be dangerous during pregnancy.