What is Gingko Biloba?

Alternate names:  Maidenhair tree, Kew tree, Japanese silver apricot 

Ginkgo is one  of the oldest living tree species. The extract  of ginkgo leaves  is used medicinally in North America, where it's one  of the most popular medicinal herbs,  and many other countries around  the world. In traditional Chinese medicine,  the seeds of the ginkgo tree  are used. 

Why Do People Use Ginkgo?

• To improve mental function 
• Alzheimer's disease
• Age-related memory loss 
• Macular degeneration 
• Sexual dysfunction 
• To enhance blood circulation 

Ginkgo leaves are  believed to contain compounds  that thin blood and help  to improve muscle tone in  the walls of  blood vessels. This may enhance blood flow. 

What are the Safety Concerns? 

Constituents in ginkgo leaves may affect blood clotting, so  ginkgo leaf extracts shouldn't be used by people with bleeding disorders. People with epilepsy (or anyone with a history of seizures) should avoid ginkgo, because it may increase  the frequency of seizures. 

Ginkgo leaf products  may affect blood sugar levels, so people with diabetes should only  be used under  the supervision of a health care provider. 

The safety of  ginkgo in pregnant or nursing women  and children isn't known. 

What are  the Side Effects  of Ginkgo? 

Side effects  of ginkgo leaf include excessive bleeding. Rarely, seizures have been reported  in people using either  the ginkgo leaf or seed. Other side effects include  digestive problems, headaches, allergic skin reactions, or muscle weakness. 

People should not consume fresh  ginkgo seeds. Roasted  ginkgo seeds may cause diarrhea, nausea, indigestion, vomiting, or allergic skin reactions. Side effects of fresh  ginkgo seeds or over 10 roasted  ginkgo seeds may include difficulty breathing, seizures, unconsciousness and death. 

Possible Drug Interactions 

Ginkgo  can increase the effect  of blood-thinners (antiplatelet or anti-clotting drugs), such as clopidogrel, ticlopidine (Ticlid), warfarin (Coumadin), heparin, and aspirin, which  may result in uncontrolled bleeding or hemorrhage. Certain herbs, such as danshen, devil's claw, eleuthero, garlic, ginger, horse chestnut, papain, red clover, and saw palmetto,  can also increase  the risk of bleeding if combined  with ginkgo. 

Ginkgo has been found to interfere with  the metabolism of drugs processed by an enzyme called cyp3A4. Ask your doctor  to check if you are taking medications  of this type. 

Ginkgo may increase the risk  of seizures if combined with other drugs  or herbs that do the same, such as antidepressants, bupropion (Wellbutrin, Zyban), certain antibiotics such as penicillin  and cephalosporins, Corticosteroids, fentanyl (Actiq, Duragesic), theophylline, methylphenidate (e.g. Concerta, Ritalin), drugs that suppress the immune system, such as azathioprine  and cyclosporine, borage, evening primrose,  and wormwood. 

Ginkgo shouldn't  be used  with the drug cyclosporine (used  to suppress the immune system), because it  has been found  to decrease the effect  of that drug. Theoretically,  ginkgo may have  the same effect with other immunosuppressant drugs. 

Ginkgo may interact with insulin  and other drugs for diabetes, such as metformin (Glucophage), glyburide (Glynase), glimepiride (Amaryl),  and glipizide (Glucotrol XL). It shouldn't be used  with medications  to prevent seizures. 

There have  been some cases  of high blood pressure  in people taking  ginkgo and thiazide diuretics, such as chlorothiazide, chlorthalidone, hydrochlorothiazide, metolazone,  and polythiazide. 

Notes: Dr. Nelson Crumfield

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EditText of this page (last edited June 20, 2010)