Ginkgo
Uses
Parts Used & Where Grown
Ginkgo biloba is the world’s oldest living species of tree. Individual trees live as long as 1,000 years. Ginkgo grows most predominantly in the southern and eastern United States, southern France, China, and Korea. The leaves of the tree are used in modern herbal medicine.
Our proprietary “Star-Rating” system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.
For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.
3 StarsReliable and relatively consistent scientific data showing a substantial health benefit.
2 StarsContradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1 StarFor an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.
This supplement has been used in connection with the following health conditions:
| Used for | Why |
|---|---|
3 Stars Age-Related Cognitive Decline 120 to 160 mg daily | Most, but not all, clinical trials have found this herb to be a safe and effective treatment for ARCD. Most but not all clinical trials, many of them double-blind, have found supplementation to be a safe and effective treatment for ARCD. |
3 Stars Glaucoma 120 mg daily of a standardized herbal extract | In cases of normal tension glaucoma; ginkgo may help improve vision. In a double-blind study, supplementation with a standardized extract of in the amount of 40 mg three times a day for four weeks partially reversed visual field damage in people with one type of glaucoma (normal tension glaucoma). |
3 Stars Intermittent Claudication 120 to 160 mg daily | Studies have reported that people with intermittent claudication see improvements in pain-free walking distance when supplementing with ginkgo. Extensive studies have been done with extracts (GBE) for treatment of intermittent claudication. Two double-blind trials found that 120 mg of GBE per day increased pain-free and total walking distance among people with intermittent claudication.Similar results were seen in another double-blind trial using 160 mg of GBE per day. In yet another double-blind trial, two doses of ginkgo extract were compared for six months. The researchers studied 60 vs. 120 mg twice daily and found that, while both amounts resulted in significant improvements in pain-free walking distance, the improvements were more pronounced at the higher dose. One double-blind study found that ginkgo extract was not beneficial. However, that study lasted only three months, whereas the positive studies lasted six months. It may take longer than three months for ginkgo to have a beneficial effect in people with intermittent claudication. |
2 Stars Altitude Sickness 80 mg twice a day | In a double-blind study of 44 people ascending to an elevation of 5,400 meters, none of those who received Ginkgo biloba extract developed altitude sickness, whereas 41% of those receiving a placebo did. In a double-blind study of 44 people ascending to an elevation of 5,400 meters, none of those who received Ginkgo biloba extract (80 mg twice a day) developed altitude sickness, whereas 41% of those receiving a placebo developed altitude sickness. Similar benefits were seen in another double-blind trial. However, in two other double-blind trials, supplementation with ginkgo did not prevent mountain sickness. |
2 Stars Alzheimer’s Disease 120 to 240 mg of a standardized herbal extract daily | Ginkgo biloba extract is an approved treatment for early-stage Alzheimer’s disease in Europe. It is thought to improve memory and quality of life and slow early disease progression. An extract made from the leaves of the Ginkgo biloba tree is an approved treatment for early-stage Alzheimer’s disease in Europe. While not a cure, extract may improve memory and quality of life and slow progression in the early stages of the disease. In addition, several double-blind trials have shown that ginkgo is helpful for people in early stages of Alzheimer’s disease, as well as for those experiencing another form of dementia known as multi-infarct dementia. Ginkgo has been found to be nearly as effective against Alzheimer's disease as donepezil, a prescription drug used to treat the condition. One trial reported no effect of ginkgo supplementation in the treatment of Alzheimer’s disease, vascular dementia or age-associated memory impairment. However, the results of this trial have been criticized, since analysis of the results does not separate those patients with Alzheimer’s disease or vascular dementia from those with age-associated memory impairment. A comparison of placebo-controlled trials of ginkgo for Alzheimer’s disease concluded that the herb compared favorably with two prescription drugs, donepezil and tacrine, commonly used to treat the condition. Research studies have used 120 to 240 mg of ginkgo, standardized to contain 6% terpene lactones and 24% flavone glycosides per day, generally divided into two or three portions. Ginkgo may need to be taken for six to eight weeks before desired actions are noticed. Ginkgo was not effective for preventing Alzheimer's disease in elderly volunteers with normal cognitive function or in those with mild cognitive impairment. |
2 Stars Depression 240 mg daily | Ginkgo may alleviate depression in elderly people not responding to antidepressant drugs. (240 mg per day) may alleviate depression in depressed elderly people not responding to antidepressant drugs. It is unknown if ginkgo could alleviate depression in other age groups. A small, preliminary trial has shown that ginkgo can reduce sexual problems caused by antidepressants like fluoxetine (Prozac), bupropion (Wellbutrin), venlafaxine (Effexor), and nefazodone (Serzone) in men and women. Double-blind trials are now needed to determine whether ginkgo is truly effective for this purpose. |
2 Stars Erectile Dysfunction 60 to 240 mg daily | The herb Ginkgo appears to increase blood flow to the penis. may help some men with ED by increasing blood flow to the penis. One double-blind trial found improvement in men taking 240 mg per day of a standardized Ginkgo biloba extract (GBE) for nine months. A preliminary trial, involving 30 men who were experiencing ED as a result of medication use (selective serotonin reuptake inhibitors and other medications), found that approximately 200 mg per day of GBE had a positive effect on sexual function in 76% of the men. |
2 Stars Macular Degeneration 120 to 240 mg daily of a standardized herbal extract | Taking ginkgo may help treat early stage macular degeneration. (Ginkgo biloba) may help treat early-stage macular degeneration, according to small, preliminary clinical trials. Many healthcare professionals recommend 120 to 240 mg of standardized extract (24% ginkgo flavone glycosides and 6% terpene lactones) in capsules or tablets per day. |
2 Stars Tardive Dyskinesia 240 mg daily | Ginkgo biloba extract EGb 761 improved symptoms of tardive dyskinesia by about 30% in schizophrenic patients. In a double-blind trial, treatment with Ginkgo biloba extract EGb 761 (240 mg per day) for 12 weeks significantly improved symptoms of tardive dyskinesia by about 30% in schizophrenic patients. Ginkgo is believed to work by functioning as an antioxidant. |
2 Stars Vertigo 120 to 160 mg a day of a standardized herbal extract | Taking ginkgo may help reduce symptoms. In a preliminary clinical trial, a standardized extract of (GBE) significantly reduced symptoms of vertigo in a group of elderly people with mild cognitive impairment. Participants were given 40 mg three times per day for one year. GBE has also been reported to significantly reduce vertigo of unknown cause in preliminary and double-blind trials. The amounts given were 120 mg and 160 mg per day, respectively, for three months. |
2 Stars Vitiligo 120 mg daily of a standardized extract | Taking ginkgo may help improve repigmentation of skin. In a double-blind study of 52 people with slowly spreading vitiligo, supplementation with Ginkgo biloba extract (standardized to contain 24% ginkgoflavonglycosides), in the amount of 40 mg three times per day for up to six months, resulted in marked to complete repigmentation in 40% of cases, compared with only 9% among those receiving a placebo. Ginkgo was also found to be effective in a preliminary trial. |
1 Star Asthma Refer to label instructions | Supplementing with the herb Ginkgo biloba may improve asthma, as its extracts block the action of a compound that contributes to asthma symptoms. extracts have been considered a potential therapy for asthma. This is because the extracts block the action of platelet-activating factor (PAF), a compound the body produces that in part causes asthma symptoms. A trial using isolated ginkgolides from ginkgo (not the whole extract) found they reduced asthma symptoms. A controlled trial used a highly concentrated tincture of ginkgo leaf and found this preparation helped decrease asthma symptoms. For asthma, 120 to 240 mg of standardized ginkgo or 3 to 4 ml of regular tincture three times daily can be used. |
1 Star Atherosclerosis Refer to label instructions | The herb Ginkgo biloba may reduce atherosclerosis risk by stopping platelets from sticking together too much. It also increases blood circulation to the brain, arms, and legs. may reduce the risk of atherosclerosis by interfering with a chemical the body sometimes makes in excess, called platelet activating factor (PAF). PAF stimulates platelets to stick together too much; ginkgo stops this from happening. Ginkgo also increases blood circulation to the brain, arms, and legs. Garlic and ginkgo also decrease excessive blood coagulation. Both have been shown in double-blind and other controlled trials to decrease the overactive coagulation of blood that may contribute to atherosclerosis. Numerous medicinal plants and plant compounds have demonstrated an ability to protect LDL cholesterol from being damaged by free radicals. Garlic, ginkgo, and guggul are of particular note in this regard. Garlic and ginkgo have been most convincingly shown to protect LDL cholesterol in humans. |
1 Star Memory Enhancement Refer to label instructions | Ginkgo may enhance cognitive performance in healthy older adults as well as people experiencing cognitive decline. The terpene lactones found in ginkgo extracts, known as ginkgolides and bilobalide, typically make up approximately 6% of the extract. They are associated with increasing circulation to the brain and other parts of the body and may exert a protective action on nerve cells. ginkgo regulates the tone and elasticity of blood vessels, making circulation more efficient. Ginkgo is also well-known for its effect on memory and thinking (cognitive function). It may enhance cognitive performance in healthy older adults,8 in people with age-related cognitive decline, and in people with Alzheimer’s disease. |
1 Star Ménière’s Disease Refer to label instructions | Ginkgo has been reported to reduce symptoms of tinnitus, vertigo, and hearing loss due to unspecified inner ear disorders. Although extract (GBE) has not been studied specifically for its effects in MD, in preliminary studies it has been reported to reduce symptoms of tinnitus, vertigo, and hearing loss due to unspecified inner ear disorders. Controlled research using GBE is needed to determine whether it is a treatment option specifically for MD. |
1 Star Migraine Headache Refer to label instructions | Ginkgo extract may also help because it inhibits the action of a substance known as platelet-activating factor, which may contribute to migraines. extract may also help because it inhibits the action of a substance known as platelet-activating factor, which may contribute to migraines. No clinical trials have examined its effectiveness in treating migraines, however. |
1 Star Multiple Sclerosis Refer to label instructions | Inflammation of nerve tissue is partly responsible for the breakdown of myelin in people with MS. In one study, people with MS showed improvement after being given injections of a constituent of ginkgo. Inflammation of nerve tissue is partly responsible for the breakdown of myelin in people with MS. When intravenous injections of a constituent of , known as ginkgolide B, were given to people with MS for five days, 80% of them reportedly improved. This specialized treatment is experimental, and it is not known whether oral use of ginkgo extracts would have a similar effect. |
1 Star Premenstrual Syndrome Refer to label instructions | Standardized herbal Ginkgo extract has been shown to alleviate PMS symptoms. A double-blind trial has shown that standardized extract, when taken daily from day 16 of one menstrual cycle to day 5 of the next menstrual cycle, alleviates congestive and psychological symptoms of PMS better than placebo. The trial used 80 mg of a ginkgo extract two times per day. |
1 Star Raynaud’s Disease Refer to label instructions | The herb Ginkgo has been reported to improve the circulation in small blood vessels and reduce pain in people with Raynaud’s disease. has been reported to improve the circulation in small blood vessels. For that reason, some doctors recommend ginkgo for people with Raynaud’s disease. One preliminary trial found that 160 mg of standardized ginkgo extract per day reduced pain in people with Raynaud’s disease. Larger clinical trials are needed to confirm ginkgo’s effectiveness for this condition. Ginkgo is often used as a standardized extract (containing 24% ginkgo flavone glycosides and 6% terpene lactones). Doctors who recommend use of ginkgo often suggest that people take 120–160 mg per day. |
1 Star Retinopathy Refer to label instructions | Using a standardized extract of ginkgo has been reported to improve visual function in people with mild diabetic retinopathy. The use of 160 mg per day of a standardized extract of for six months has been reported in a small double-blind trial to improve impaired visual function in people with mild diabetic retinopathy. |
1 Star Tinnitus Refer to label instructions | The herb ginkgo may be useful in treating tinnitus. has been used to treat tinnitus, with mixed results. The largest placebo-controlled trial to date failed to find any effect of 150 mg per day of ginkgo extract in people with tinnitus. Two smaller, controlled trials have found that standardized ginkgo extract (120 mg per day, containing 24% flavone glycosides and 6% terpene lactones), was effective at relieving the symptoms of tinnitus. One trial failed to find ginkgo beneficial, but used less than 30 mg of ginkgo extract per day, an amount unlikely to have any therapeutic effect. |
1 Star Type 1 Diabetes Refer to label instructions | Ginkgo may improve metabolism and help prevent complications of type 1 diabetes. Ginkgo (Ginkgo biloba) extract may be useful to people with type 1 diabetes because of its abilities to raise antioxidant capacity and reduce inflammatory signaling. A standardized ginkgo extract was found to improve insulin production and glucose metabolism and decrease triglyceride levels in an animal model of type 1 diabetes. Preliminary evidence from a trial in subjects with long-standing type 1 diabetes suggests it may have a role in protecting vision. Other animal research and a single small, uncontrolled, pilot trial indicate ginkgo may protect nerve function and prove useful for prevention and treatment of diabetic nerve damage (neuropathy). |
1 Star Type 2 Diabetes 120 mg daily | Ginkgo may improve the efficacy of commonly used anti-diabetes medications. It also appears to help prevent and treat type 2 diabetes-related complications. Ginkgo (Ginkgo biloba) extract was found in a placebo-controlled trial to enhance the HbA1c-lowering effect of the widely used anti-diabetes drug metformin, while not directly altering metabolism of the drug. In another placebo-controlled trial that included participants whose type 2 diabetes was not well controlled by metformin, adding 120 mg per day of ginkgo resulted in greater reductions in HbA1c and fasting blood glucose and insulin levels, as well as body-mass index (BMI), waist circumference, and abdominal fat, after 90 days. Clinical research has shown ginkgo extract can improve kidney function in people with type 2 diabetes and early signs of nephropathy (kidney damage), and strengthen retinal blood flow in those with diabetic retinopathy (damage to the visual center of the eye). Treatment with the combination of ginkgo leaf plus a traditional Chinese herbal remedy (Liuwei Dihuang Pills) reduced the risks of developing retinopathy or nephropathy in a placebo-controlled trial that included 140 people with type 2 diabetes who were monitored for three years. Findings from animal studies suggests ginkgo may also have protective effects on nerve tissue and may be helpful in preventing and treating type 2 diabetes-related neuropathy (nerve dysfunction). |
Traditional Use (May Not Be Supported by Scientific Studies)
Medicinal use of ginkgo can be traced back almost 5,000 years in Chinese herbal medicine. The nuts of the tree were most commonly recommended and used to treat respiratory tract ailments. The use of the leaves is a modern development originating in Europe.
How It Works
How It Works
The medical benefits of Ginkgo biloba extract are attributed primarily to two groups of active constituents: the ginkgo flavone glycosides and the terpene lactones. Ginkgo flavone glycosides, which typically make up approximately 24% of the extract, are primarily responsible for ginkgo’s antioxidant activity and may mildly inhibit platelet aggregation (stickiness). These two actions may help ginkgo prevent circulatory diseases, such as atherosclerosis, and support the brain and central nervous system.1 In addition to the cardiovascular system, ginkgo’s antioxidant action may also extend to the brain and retina of the eye.2 Preliminary trials have suggested potential benefit for people with macular degeneration3 and diabetic retinopathy.4 The terpene lactones found in ginkgo extracts, known as ginkgolides and bilobalide, typically make up approximately 6% of the extract. They are associated with increasing circulation to the brain and other parts of the body and may exert a protective action on nerve cells.5 ginkgo regulates the tone and elasticity of blood vessels,6 making circulation more efficient.7
Ginkgo is also well-known for its effect on memory and thinking (cognitive function). It may enhance cognitive performance in healthy older adults,8 in people with age-related cognitive decline, and in people with Alzheimer’s disease.
How to Use It
Most clinical trials have used between 120 and 240 mg of ginkgo (standardized to contain 6% terpene lactones and 24% flavone glycosides) per day, generally divided into two or three portions.9 The higher amount (240 mg per day) has been used in some people with mild-to-moderate Alzheimer’s disease, age-related cognitive decline, intermittent claudication, and resistant depression. Ginkgo may need to be taken for eight to twelve weeks before desired actions such as cognitive improvement are noticed. Although nonstandardized Ginkgo biloba leaf and tinctures are available, there is no well-established amount or use for these forms.
Interactions
Interactions with Supplements, Foods, & Other Compounds
Interactions with Medicines
Certain medicines interact with this supplement.
Replenish Depleted Nutrients
none
Reduce Side Effects
- Citalopram
Ginkgo biloba extract may reduce the side effects experienced by some persons taking SSRIs such as fluoxetine or sertraline. An open-label study with elderly, depressed persons found that 200–240 mg of ginkgo per day was effective in alleviating sexual side effects in both men and women taking SSRIs. One case study reported that 180 to 240 mg of GBE daily reduced genital anesthesia and sexual side effects secondary to fluoxetine use in a 37-year-old woman.
- Cyclosporine
Ginkgo was reported to protect liver cells from damage caused by cyclosporine in a test tube experiment. A Ginkgo biloba extract partially reversed cyclosporine-induced reduced kidney function in a study of isolated rat kidneys. Human trials have not studied the actions of ginkgo to prevent or reduce the side effects of cyclosporine.
- Fluoxetine
Ginkgo biloba extract (GBE) may reduce the side effects experienced by some persons taking SSRIs such as fluoxetine or sertraline. An open-label study with elderly, depressed persons found that 200–240 mg of GBE daily was effective in alleviating sexual side effects in both men and women taking SSRIs. One case study reported that 180–240 mg of GBE daily reduced genital anesthesia and sexual side effects secondary to fluoxetine use in a 37-year-old woman.
- Fluvoxamine
Ginkgo biloba extract may reduce the side effects experienced by some persons taking SSRIs such as fluoxetine or sertraline. An open-label study with elderly, depressed persons found that 200 to 240 mg of ginkgo daily was effective in alleviating sexual side effects in both men and women taking SSRIs.
One case study reported that 180–240 mg of GBE daily reduced genital anesthesia and sexual side effects secondary to fluoxetine use in a 37-year-old woman.
- Haloperidol
In a double-blind trial, supplementation of schizophrenic patients with Ginkgo biloba extract, in the amount of 250 mg per 2.2 pounds of body weight per day for 12 weeks, enhanced the effectiveness of haloperidol and also reduced the side effects of the drug.
- Paroxetine
In three men and two women treated with fluoxetine or sertraline (SSRI drugs closely related to paroxetine) for depression who experienced sexual dysfunction, addition of Ginkgo biloba extract (GBE) in the amount of 240 mg per day effectively reversed the sexual dysfunction. This makes sense because ginkgo has been reported to help men with some forms of erectile dysfunction.
- Sertraline
In three men and two women treated with fluoxetine or sertraline (SSRI drugs closely related to paroxetine) for depression who experienced sexual dysfunction, addition of Ginkgo biloba extract (GBE) in the amount of 240 mg per day effectively reversed the sexual dysfunction. This makes sense because ginkgo has been reported to help men with some forms of erectile dysfunction.
Support Medicine
- ClozapineIn one study, treatment with 120 mg per day of Ginkgo biloba extract for 12 weeks enhanced the beneficial effect of clozapine on certain symptoms of schizophrenia in patients who had not responded adequately to clozapine by itself.
Reduces Effectiveness
none
Potential Negative Interaction
- Aspirin
There have been two case reports suggesting a possible interaction between ginkgo Ginkgo biloba and an anticoagulant drug or aspirin leading to increased bleeding. In the first, a 78-year-old woman taking warfarin developed bleeding within the brain following the concomitant use of ginkgo (the amount used is not given in the case report). In the second, a 70-year-old man developed slow bleeding behind the iris of the eye (spontaneous hyphema) following use of ginkgo (80 mg per day) together with aspirin (325 mg per day). While this interaction is unproven, anyone taking anticoagulant medications or aspirin should inform their physician before using ginkgo.
- Bendroflumethiazide
One case was reported in which ginkgo use was associated with high blood pressure in a person treated with a thiazide diuretic. Ginkgo was not proven to be the cause of this reaction.
- Chlorothiazide
One case was reported in which ginkgo use was associated with high blood pressure in a person treated with a thiazide diuretic. Ginkgo was not proven to be the cause of this reaction.
- Chlorpropamide
In a preliminary trial, administration of Ginkgo biloba who were taking oral anti-diabetes medication resulted in a significant worsening of glucose tolerance. Ginkgo did not impair glucose tolerance in individuals whose diabetes was controlled by diet. Individuals taking oral anti-diabetes medication should consult a doctor before taking Ginkgo biloba.
- Chlorthalidone
One case was reported in which ginkgo use was associated with high blood pressure in a person treated with a thiazide diuretic. Ginkgo was not proven to be the cause of this reaction.
- Glimepiride
In a preliminary trial, administration of Ginkgo biloba extract (120 mg per day) for three months to patients with type 2 diabetes who were taking oral anti-diabetes medication resulted in a significant worsening of glucose tolerance. Ginkgo did not impair glucose tolerance in individuals whose diabetes was controlled by diet. Individuals taking oral anti-diabetes medication should consult a doctor before taking Ginkgo biloba.
- Glyburide
In a preliminary trial, administration of Ginkgo biloba extract (120 mg per day) for three months to patients with type 2 diabetes who were taking oral anti-diabetes medication resulted in a significant worsening of glucose tolerance. Ginkgo did not impair glucose tolerance in individuals whose diabetes was controlled by diet. Individuals taking oral anti-diabetes medication should consult a doctor before taking Ginkgo biloba.
- Glyburide Micronized
In a preliminary trial, administration of Ginkgo biloba who were taking oral anti-diabetes medication resulted in a significant worsening of glucose tolerance. Ginkgo did not impair glucose tolerance in individuals whose diabetes was controlled by diet. Individuals taking oral anti-diabetes medication should consult a doctor before taking Ginkgo biloba.
- Heparin
Ginkgo extracts may reduce the ability of platelets to stick together, possibly increasing the tendency toward bleeding. Standardized extracts of ginkgo have been associated with two cases of spontaneous bleeding, although the ginkgo extracts were not definitively shown to be the cause of the problem. People taking heparin should consult with a physician knowledgeable about botanical medicines if they are considering taking ginkgo.
- Hydrochlorothiazide
One case was reported in which ginkgo use was associated with high blood pressure in a person treated with a thiazide diuretic. Ginkgo was not proven to be the cause of this reaction.
- Hydroflumethiazide
One case was reported in which ginkgo use was associated with high blood pressure in a person treated with a thiazide diuretic. Ginkgo was not proven to be the cause of this reaction.
- IbuprofenIt has been argued that ginkgo has a blood-thinning effect and might therefore further increase the risk of bleeing when taken in combination with drugs (including ibuprofen) that thin the blood. However, the bulk of the evidence suggests that ginkgo does not, in fact, have a blood-thinning effect.
- Indapamide
One case was reported in which ginkgo use was associated with high blood pressure in a person treated with a thiazide diuretic. Ginkgo was not proven to be the cause of this reaction.
- Metformin
In a preliminary trial, administration of Ginkgo biloba extract (120 mg per day) for three months to patients with type 2 diabetes who were taking oral anti-diabetes medication resulted in a significant worsening of glucose tolerance. Ginkgo did not impair glucose tolerance in individuals whose diabetes was controlled by diet. Individuals taking oral anti-diabetes medication should consult a doctor before taking Ginkgo biloba.
- Methyclothiazide
One case was reported in which ginkgo use was associated with high blood pressure in a person treated with a thiazide diuretic. Ginkgo was not proven to be the cause of this reaction.
- Metolazone
One case was reported in which ginkgo use was associated with high blood pressure in a person treated with a thiazide diuretic. Ginkgo was not proven to be the cause of this reaction.
- Polythiazide
One case was reported in which ginkgo use was associated with high blood pressure in a person treated with a thiazide diuretic. Ginkgo was not proven to be the cause of this reaction.
- Repaglinide
In a preliminary trial, administration of Ginkgo biloba extract (120 mg per day) for three months to patients with type 2 diabetes who were taking oral anti-diabetes medication resulted in a significant worsening of glucose tolerance. Ginkgo did not impair glucose tolerance in individuals whose diabetes was controlled by diet. Individuals taking oral anti-diabetes medication should consult a doctor before taking Ginkgo biloba.
- Ticlopidine
Ginkgo extracts may reduce the ability of platelets to stick together, possibly increasing the tendency toward bleeding. In a rat study, a high intake of ginkgo increased the action of ticlopidine in a way that could prove dangerous if the same effect occurred in people. Standardized extracts of ginkgo have been associated with two cases of spontaneous bleeding, although the ginkgo extracts were not definitively shown to be the cause of the problem. People taking ticlopidine should use ginkgo extracts only under the supervision of a doctor.
- Tolbutamide
In a preliminary trial, administration of Ginkgo biloba who were taking oral anti-diabetes medication resulted in a significant worsening of glucose tolerance. Ginkgo did not impair glucose tolerance in individuals whose diabetes was controlled by diet. Individuals taking oral anti-diabetes medication should consult a doctor before taking Ginkgo biloba.
- Trazodone
There is one case report of an elderly patient with Alzheimer’s disease going into a coma while concurrently using trazodone and ginkgo. Until more is known, ginkgo should not be combined with trazodone except under supervision of a doctor.
- Trichlormethiazide
One case was reported in which ginkgo use was associated with high blood pressure in a person treated with a thiazide diuretic. Ginkgo was not proven to be the cause of this reaction.
- Warfarin
Ginkgo extracts may reduce the ability of platelets to stick together, possibly increasing the tendency toward bleeding. Standardized extracts of ginkgo have been associated with two cases of spontaneous bleeding, although the ginkgo extracts were not definitively shown to be the cause of the problem. There are two case reports of people taking warfarin in whom bleeding occurred after the addition of ginkgo. People taking warfarin should consult with a physician knowledgeable about botanical medicines if they are considering taking ginkgo.
Explanation Required
none
Side Effects
Side Effects
Excessive bleeding has been reported in a few individuals taking ginkgo,10, 11 although a cause/effect relationship was not proven. A review of 18 randomized controlled trials with a total of 1,985 adults concluded that it is unlikely that taking ginkgo increases the risk of bleeding.12 In addition, two elderly individuals with well-controlled epilepsy developed recurrent seizures within two weeks after starting ginkgo.13 Mild headaches lasting for a day or two and mild upset stomach have been reported in a small number of people using ginkgo.
Ginkgo leaves are known to contain a group of potentially toxic constituents known as alkylphenols. To reduce the potential for adverse effects, the German Commission E Monograph requires that ginkgo products for human consumption contain less than 5 parts per million of alkylphenols.14
One small clinical trial found that ginkgo supplementation for three months increased secretion of insulin by the pancreas, but did not affect blood glucose levels, in healthy young adults.15 These results suggest that the participants may have developed an insensitivity to insulin, a potential concern because insulin insensitivity may be a precursor to type 2 diabetes. However, this trial does not prove that ginkgo causes insulin insensitivity, nor does it prove that long-term ginkgo supplementation increases the risk for any disease. In addition, the results of this trial are not consistent with other research on ginkgo. Larger and more rigorously designed clinical trials of ginkgo supplementation have found no significant adverse effects after as many as 12 months of supplementation.16
People should seek an accurate medical diagnosis prior to self-prescribing ginkgo. This is especially important for the elderly, whose circulatory conditions can involve serious disease, and for people scheduled for surgery, as ginkgo may affect bleeding time.
References
1. Drieu K. Preparation and definition of Ginkgo biloba extract. In: Rokan (Ginkgo biloba): Recent Results in Pharmacology and Clinic. Fünfgeld EW, ed. Berlin: Springer-Verlag, 32-6.
2. Ferrandini C, Droy-Lefaix MT, Christen Y, eds. Ginkgo biloba Extract (EGb 761) as a Free Radical Scavenger. Paris: Elsevier, 1993.
3. Lebuisson DA, Leroy L, Rigal G. Treatment of senile macular degeneration with Ginkgo biloba extract. A preliminary double-blind, drug versus placebo study. Presse Med 1986;15:1556-8 [in French].
4. Lanthony P, Cosson JP. The course of color vision in early diabetic retinopathy treated with Ginkgo biloba extract. A preliminary double-blind versus placebo study. J Fr Ophtalmol 1988;11:671-4 [in French].
5. Krieglstein J. Neuroprotective properties of Ginkgo biloba—constituents. Zeitschrift Phytother 1994;15:92-6.
6. Clostre F. From the body to the cell membranes: the different levels of pharmacological action of Ginkgo biloba extract. In: Rokan(Ginkgo biloba): Recent Results in Pharmacology and Clinic. Fünfgeld EW, ed. Berlin: Springer-Verlag, 1988, 180-98.
7. Jung F, Mrowietz C, Kiesewetter H, Wenzel E. Effect of Ginkgo biloba on fluidity of blood and peripheral microcirculation in volunteers. Arzneimittelforschung 1990;40:589-93.
8. Mix JA, Crews WD. An examination of the efficacy of Ginkgo biloba extract EGb761 on the neuropsychologic functioning of cognitively intact older adults. J Altern Complement Med 2000;6:219-29.
9. Blumenthal M, Busse WR, Goldberg A, et al, eds. The Complete Commission E Monographs: Therapeutic Guide to Herbal Medicines. Boston, MA: Integrative Medicine Communications, 1998, 136-8.
10. Matthews MK Jr. Association of Ginkgo biloba with intracerebral hemorrhage. Neurology 1998;50:1933-4 [letter].
11. Rosenblatt M, Mindel J. Spontaneous hyphema associated with ingestion of Ginkgo biloba extract. N Engl J Med 1997;336:1108 [letter].
12. Kellermann AJ, Kloft C. Is there a risk of bleeding associated with standardized Ginkgo biloba extract therapy? A systematic review and meta-analysis. Pharmacotherapy 2011;31:490-502.
13. Granger AS. Ginkgo biloba precipitating epileptic seizures. Age Ageing 2001;30:523-5.
14. Siegers CP. Cytotoxicity of alkylphenols from Ginkgo biloba. Phytomedicine 1999;6:281-3.
15. Kudolo GB. The effect of 3-month ingestion of Ginkgo biloba extract on pancreatic ß-cell function in response to glucose loading in normal glucose-tolerant individuals. J Clin Pharmacol 2000;40:647-54.
16. Le Bars PL, Katz MM, Berman N, et al. A placebo-controlled, double-blind, randomized trial of an extract of Ginkgo biloba for dementia. North American EGb Study Group. JAMA 1997;278:1327-32.
Last Review: 05-24-2015
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