The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. 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.