Interactions with Drugs
Alprazolam (Xanax)
Interaction Rating = Moderate Be cautious with this combination.
Severity = Mild • Occurrence = Probable • Level of Evidence = B
Ginkgo might decrease the effectiveness of alprazolam in some patients. Ginkgo extract 120 mg twice daily (Ginkgold), seems to decrease alprazolam levels by about 17%. However, ginkgo does not appear to decrease the elimination half-life of alprazolam. This suggests that ginkgo is more likely to decrease absorption of alprazolam rather than induce hepatic metabolism of alprazolam.
Anticoagulant/Antiplatelet Drugs
Interaction Rating = Moderate Be cautious with this combination.
Severity = High • Occurrence = Possible • Level of Evidence = A
Several pharmacodynamic studies suggest that ginkgo inhibits platelet aggregation. It is thought that the ginkgo constituent, ginkgolide B, displaces platelet-activating factor (PAF) from its binding sites, decreasing blood coagulation. Several case reports have documented serious bleeding events in patients taking ginkgo. However, population and clinical studies have produced mixed results. Some evidence shows that short-term use of ginkgo leaf does not significantly reduce platelet aggregation and blood clotting. A study in healthy men who took a specific ginkgo leaf extract (EGb 761) 160 mg twice daily for 7 days found that participants did not have reduced prothrombin time. A meta-analysis of 18 studies using standardized ginkgo extracts, 80-480 mg daily for up to 32 weeks, did not find a significant effect on platelet aggregation, fibrinogen concentration, or PT/aPTT. In addition, a single dose of ginkgo plus clopidogrel (Plavix) does not seem to significantly increase bleeding time. Similarly, a single dose of ginkgo extract 80 mg plus ticlopidine (Ticlid) 250 mg does not seem to significantly affect bleeding time, platelet aggregation, or pharmacokinetics of ticlopidine. Despite these negative findings, an analysis of a large medical record database suggests that gingko increases the risk of a bleeding adverse event by 38% when taken concurrently with warfarin. It has been suggested that ginkgo has to be taken for at least 2-3 weeks to have a significant effect on platelet aggregation. Until more is known, use ginkgo cautiously patients who are taking antiplatelet or anticoagulant drugs. Some of these drugs include aspirin, clopidogrel (Plavix), dalteparin (Fragmin), enoxaparin (Lovenox), heparin, indomethacin (Indocin), ticlopidine (Ticlid), warfarin (Coumadin), and others.
Anticonvulsants
Interaction Rating = Moderate Be cautious with this combination.
Severity = High • Occurrence = Possible • Level of Evidence = D
Consumption of ginkgo seeds can cause seizures due to ginkgotoxin contained in the seeds. Large amounts of ginkgotoxin can cause neurotoxicity and seizure. Ginkgotoxin is present in much larger amounts in ginkgo seeds than leaves. Ginkgo leaf extract contains trace amounts of ginkgotoxin. The amount of ginkgotoxin in ginkgo leaf and leaf extract seems unlikely to cause toxicity. However, there are anecdotal reports of seizure occurring after use of ginkgo leaf both in patients without a history of seizure disorder and in those with previously well-controlled epilepsy. Theoretically, taking ginkgo might reduce the effectiveness of anticonvulsants for preventing seizure. Some anti-epileptic drugs include phenobarbital, primidone (Mysoline), valproic acid (Depakene), gabapentin (Neurontin), carbamazepine (Tegretol), phenytoin (Dilantin), and others.
Antidepressant Drugs
Interaction Rating = Moderate Be cautious with this combination.
Severity = Moderate • Occurrence = Possible • Level of Evidence = D
In vitro and ex vivo evidence suggests that ginkgo may increase synaptosomal reuptake of serotonin. Theoretically, taking serotonergic antidepressants with ginkgo might decrease their efficacy. These drugs include the selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine (Prozac), paroxetine (Paxil), sertraline (Zoloft), and others; and tricyclic and atypical antidepressants such as amitriptyline (Elavil), clomipramine (Anafranil), imipramine (Tofranil), and others.
Antidiabetes Drugs
Interaction Rating = Moderate Be cautious with this combination.
Severity = Moderate • Occurrence = Possible • Level of Evidence = B
Ginkgo leaf extract seems to alter insulin secretion and metabolism, and might affect blood glucose levels in people with type 2 diabetes. The effect of ginkgo seems to differ depending on the insulin and treatment status of the patient. In diet-controlled diabetes patients with hyperinsulinemia, taking ginkgo does not seem to significantly affect insulin or blood glucose levels. In patients with hyperinsulinemia who are treated with oral hypoglycemic agents, taking ginkgo seems to decrease insulin levels and increase blood glucose following an oral glucose tolerance test. Researchers speculate that this could be due to ginkgo-enhanced hepatic metabolism of insulin. In patients with pancreatic exhaustion, taking ginkgo seems to stimulate pancreatic beta-cells resulting in increased insulin and C-peptide levels, but no significant change in blood glucose levels in response to an oral glucose tolerance test. Theoretically, taking ginkgo might alter the response to antidiabetes drugs. Advise patients with type 2 diabetes to use ginkgo cautiously. Some antidiabetes drugs include glimepiride (Amaryl), glyburide (DiaBeta, Glynase PresTab, Micronase), insulin, pioglitazone (Actos), rosiglitazone (Avandia), and others.
Atorvastatin (Lipitor)
Interaction Rating = Moderate Be cautious with this combination.
Severity = Mild • Occurrence = Probable • Level of Evidence = B
In humans, intake of ginkgo extract appears to increase atorvastatin clearance, reducing the area under the curve of atorvastatin by 10% to 14% and the maximum concentration by 29%. However, this interaction does not appear to affects cholesterol synthesis and absorption. Until more is known, advise patients to use ginkgo cautiously if they take atorvastatin.
Buspirone (Buspar)
Interaction Rating = Moderate Be cautious with this combination.
Severity = High • Occurrence = Unlikely • Level of Evidence = D
Ginkgo in combination with fluoxetine (Prozac), St. John’s wort, melatonin, and buspirone (BuSpar) might cause hypomania in patients with depression. Whether ginkgo alone or in combination with buspirone can cause hypomania is unknown.
Cytochrome P450 1A2 (CYP1A2) Substrates
Interaction Rating = Moderate Be cautious with this combination.
Severity = Moderate • Occurrence = Possible • Level of Evidence = B
There is preliminary evidence that ginkgo leaf extract can mildly inhibit cytochrome P450 1A2 (CYP1A2) enzymes. However, clinical research suggests ginkgo might not affect CYP1A2. Until more is known, use ginkgo cautiously in patients taking drugs metabolized by these enzymes. Some drugs metabolized by CYP1A2 include acetaminophen (Tylenol), amitriptyline (Elavil), clopidogrel (Plavix), clozapine (Clozaril), diazepam (Valium), estradiol, olanzapine (Zyprexa), ondansetron (Zofran), propranolol (Inderal), ropinirole (Requip), tacrine (Cognex), theophylline, verapamil (Calan, Covera-HS, Isoptin, Verelan), warfarin (Coumadin), and others.
Cytochrome P450 2C19 (CYP2C19) Substrates
Interaction Rating = Moderate Be cautious with this combination.
Severity = Moderate • Occurrence = Probable • Level of Evidence = B
There is some evidence that a specific ginkgo leaf extract (Remembrance, Herbs Product LTD, Hong Kong) 140 mg twice daily can induce CYP2C19 enzymes and potentially decrease levels of drugs metabolized by these enzymes. However, other clinical research shows that taking ginkgo biloba 120 mg twice daily for 12 days has no effect on levels of drugs metabolized by CYP2C19. Until more is known, advise patients to use ginkgo cautiously if they take any CYP2C19 substrate. Some drugs metabolized by CYP2C19 include amitriptyline (Elavil), carisoprodol (Soma), citalopram (Celexa), diazepam (Valium), lansoprazole (Prevacid), omeprazole (Prilosec), phenytoin (Dilantin), voriconazole, warfarin, and many others.
Cytochrome P450 2C9 (CYP2C9) Substrates
Interaction Rating = Moderate Be cautious with this combination.
Severity = Moderate • Occurrence = Possible • Level of Evidence = D
There is preliminary evidence that a specific standardized extract of ginkgo leaf (EGb 761) can significantly inhibit CYP2C9 in vitro. The terpenoid (ginkgolides) and flavonoid (quercetin, kaempferol, etc.) constituents seem to be responsible for the enzyme inhibition. Most ginkgo extracts contain some amount of these constituents. Therefore, other ginkgo leaf extracts might also inhibit the CYP2C9 enzyme in vitro. However, clinical research suggests that ginkgo might not have a significant effect on CYP2C9 in humans. Ginkgo does not seem to significantly affect the pharmacokinetics of CYP2C9 substrates diclofenac or tolbutamide. Until more is known, advise patients to use ginkgo cautiously if they take any CYP2C9 substrate. Some of these drugs include include amitriptyline (Elavil), diazepam (Valium), zileuton (Zyflo), celecoxib (Celebrex), diclofenac (Voltaren), fluvastatin (Lescol), glipizide (Glucotrol), ibuprofen (Advil, Motrin), irbesartan (Avapro), losartan (Cozaar), phenytoin (Dilantin), piroxicam (Feldene), tamoxifen (Nolvadex), tolbutamide (Tolinase), torsemide (Demadex), warfarin (Coumadin), and others.warfarin (Coumadin), glyburide, glipizide, amitriptyline valdecoxib (Bextra), phenytoin (Dilantin), and many others.
Cytochrome P450 2D6 (CYP2D6) Substrates
Interaction Rating = Moderate Be cautious with this combination.
Severity = Moderate • Occurrence = Possible • Level of Evidence = B
There is preliminary evidence that ginkgo leaf extract can modestly inhibit CYP2D6 enzymes by about 9%. This might not result in clinical significant changes in levels of drug metabolized by CYP2D6. Preliminary clinical research also suggests that ginkgo does not significantly affect levels of donepezil, a CYP2D6 substrate. Other clinical research also suggests ginkgo does not inhibit CYP2D6. Until more is known, use ginkgo cautiously in patients taking CYP2D6 substrates. Some drugs metabolized by CYP2D6 include amitriptyline (Elavil), clozapine (Clozaril), codeine, desipramine (Norpramin), donepezil (Aricept), fentanyl (Duragesic), flecainide (Tambocor), fluoxetine (Prozac), meperidine (Demerol), methadone (Dolophine), metoprolol (Lopressor, Toprol XL), olanzapine (Zyprexa), ondansetron (Zofran), tramadol (Ultram), trazodone (Desyrel), and others.
Cytochrome P450 3A4 (CYP3A4) Substrates
Interaction Rating = Moderate Be cautious with this combination.
Severity = Moderate • Occurrence = Possible • Level of Evidence = B
There is conflicting evidence about whether ginkgo induces or inhibits CYP3A4. Ginkgo does not appear to affect hepatic CYP3A4. However, it is not known if ginkgo affects intestinal CYP3A4. Preliminary clinical research suggests that taking ginkgo does not significantly affect levels of donepezil, lopinavir, or ritonavir, which are all CYP3A4 substrates. Other clinical research also suggests ginkgo does not significantly affect CYP3A4 activity. However, there are two case reports of decreased efavirenz concentrations and increased viral load in patients taking ginkgo. It is suspected that terpenoids from the ginkgo extract reduced drug levels by inducing cytochrome P450 3A4 (CYP3A4). Until more is known, use ginkgo cautiously in patients taking drugs metabolized by CYP3A4. Some drugs metabolized by CYP3A4 include lovastatin (Mevacor), clarithromycin (Biaxin), cyclosporine (Neoral, Sandimmune), diltiazem (Cardizem), estrogens, indinavir (Crixivan), triazolam (Halcion), and others.
Efavirenz (Sustiva)
Interaction Rating = Moderate Be cautious with this combination.
Severity = High • Occurrence = Possible • Level of Evidence = D
There are two case reports of decreased efavirenz concentrations and increased viral load in patients taking ginkgo. In one case, an HIV-positive male experienced over a 50% decrease in efavirenz levels over the course of 14 months while taking ginkgo extract. HIV-1 RNA copies also increased substantially, from less than 50, to more than 1500. It is suspected that terpenoids from the ginkgo extract reduced drug levels by inducing cytochrome P450 3A4 (CYP3A4). In another case report, a patient stable on antiviral therapy including efavirenz for 10 years, had an increase in viral load from <50 copies/mL to 1350 copies/mL after 2 months of taking a combination of supplements including ginkgo. After stopping ginkgo, the viral load was again controlled with the same antiviral therapy regimen. Advise patients to use caution if taking ginkgo with efavirenz.
Fluoxetine (Prozac)
Interaction Rating = Moderate Be cautious with this combination.
Severity = High • Occurrence = Unlikely • Level of Evidence = D
Ginkgo in combination with fluoxetine, buspirone (BuSpar), St. John’s wort, and melatonin might cause hypomania in patients with depression. Whether ginkgo alone or in combination with fluoxetine can cause hypomania is unknown.
Hydrochlorothiazide
Interaction Rating = Minor Be watchful with this combination.
Severity = Mild • Occurrence = Unlikely • Level of Evidence = D
There is a single case report of a patient experiencing hypertension after taking ginkgo along with hydrochlorothiazide. Monitor patient using this combination for potential hypertensive exacerbations.
Ibuprofen (Advil, Others)
Interaction Rating = Moderate Be cautious with this combination.
Severity = High • Occurrence = Possible • Level of Evidence = D
Ginkgo might have antiplatelet effects and has been associated with several case reports of spontaneous bleeding. Theoretically, combining ginkgo with ibuprofen might have additive antiplatelet effects and increase the risk of bleeding. In one case, a 71-year-old man had taken a specific ginkgo extract (Gingium, Biocur, Germany) 40 mg twice daily for 2.5 years. About 4 weeks after starting ibuprofen 600 mg daily he experienced a fatal intracerebral hemorrhage. However, the antiplatelet effects of ginkgo have been questioned. A meta-analysis and other studies have not found a significant antiplatelet effect with standardized ginkgo extracts, 80 mg to 480 mg taken daily for up to 32 weeks.
Nifedipine (Procardia)
Interaction Rating = Minor Be watchful with this combination.
Severity = Mild • Occurrence = Possible • Level of Evidence = B
Animal research and some clinical evidence suggests that taking ginkgo leaf extract orally in combination with oral nifedipine might increase nifedipine levels and cause increased side effects, such as headaches, dizziness, and hot flushes. However, taking ginkgo orally does not seem to affect the pharmacokinetics of intravenously administered nifedipine.
Non-Nucleoside Reverse Transcriptase Inhibitors (Nnrtis)
Interaction Rating = Moderate Be cautious with this combination.
Severity = High • Occurrence = Possible • Level of Evidence = B
Ginkgo may affect the levels and thus the activity of some non-nucleoside reverse transcriptase inhibitors (NNRTIs), but results are conflicting. There are two case reports of decreased efavirenz concentrations and increased viral load in patients taking ginkgo. It is suspected that terpenoids from the ginkgo extract reduced efavirenz levels by inducing cytochrome P450 3A4 (CYP3A4). However, data from a pharmacokinetic study shows that taking a specific ginkgo formulation (Tavonin, Willmar Schwbe GmbH) for 14 days does not affect the levels of the NNRTI raltegravir (Isentress). Unlike efavirenz, which is principally metabolized by CYP3A4, raltegravir is metabolized by UGT1A1-mediated glucuronidation. Therefore the levels of raltegravir are not influenced by the effects of ginkgo on CYP3A4 activity. Advise patients to use caution when taking ginkgo with NNRTIs that are metabolized by CYP3A4. Ginkgo may decrease the levels and activity of these NNRTIs.Some NNRTIs that are metabolized by CYP3A4 include delavirdine (Rescriptor), efavirenz (Sustiva), etravirine (Intelence), nevirapine (Viramune), and rilpivirine (Edurant).
Omeprazole (Prilosec)
Interaction Rating = Minor Be watchful with this combination.
Severity = Mild • Occurrence = Possible • Level of Evidence = B
A specific ginkgo leaf extract (Remembrance, Herbs Product LTD, Hong Kong) 140 mg twice daily can induce CYP2C19 enzymes and decrease levels of omeprazole by about 27% to 42%.
P-Glycoprotein Substrates
Interaction Rating = Moderate Be cautious with this combination.
Severity = High • Occurrence = Possible • Level of Evidence = B
Ginkgo might inhibit P-glycoprotein and increase the effects and adverse effects P-glycoprotein substrates. P-glycoprotein is an efflux transporter that pumps drugs and other substances out of cells. For example, it can pump drugs from intestinal epithelial cells back into the intestinal lumen. A small clinical study in healthy volunteers shows that using ginkgo leaf extract 120 mg orally three times daily for 14 days can increase levels of the P-glycoprotein substrate, talinolol, by 36% in healthy male individuals. However, single doses of ginkgo do not have the same effect. Theoretically ginkgo might increase the concentration of other P-glycoprotein substrates. Drugs that might be affected include some chemotherapeutic agents (etoposide, paclitaxel, vinblastine, vincristine, vindesine), antifungals (ketoconazole, itraconazole), protease inhibitors (amprenavir, indinavir, nelfinavir, saquinavir), H2 antagonists (cimetidine, ranitidine), some calcium channel blockers (diltiazem, verapamil), corticosteroids, erythromycin, cisapride (Propulsid), fexofenadine (Allegra), cyclosporine, loperamide (Imodium), quinidine, and others.
Risperidone (Risperdal)
Interaction Rating = Moderate Be cautious with this combination.
Severity = Moderate • Occurrence = Possible • Level of Evidence = D
A single case of priapism has bene reported for a 26 year-old schizophrenic man who used risperidone 3 mg/day along with ginkgo extract 160 mg/day (87796). Risperidone is metabolized by cytochrome P450 2D6 (CYP2D6) and cytochrome P450 3A4 (CYP3A4). These enzymes are inhibited by ginkgo. Theoretically, ginkgo may inhibit the metabolism of risperidone and increase the risk of adverse effects.
Seizure Threshold Lowering Drugs
Interaction Rating = Moderate Be cautious with this combination.
Severity = High • Occurrence = Possible • Level of Evidence = D
Consumption of ginkgo seeds can cause seizures due to ginkgotoxin contained in the seeds. Large amounts of ginkgotoxin can cause neurotoxicity and seizure. Ginkgotoxin is present in much larger amounts in ginkgo seeds than leaves. Ginkgo leaf extract contains trace amounts of ginkgotoxin. The amount of ginkgotoxin in ginkgo leaf and leaf extract seems unlikely to cause toxicity. However, there are anecdotal reports of seizure occurring after use of ginkgo leaf both in patients without a history of seizure disorder and in those with previously well-controlled epilepsy. Advise patients taking these drugs to avoid ginkgo leaf products. Some drugs that lower the seizure threshold include anesthetics (propofol, others), antiarrhythmics (mexiletine), antibiotics (amphotericin, penicillin, cephalosporins, imipenem), antidepressants (bupropion, others), antihistamines (cyproheptadine, others), immunosuppressants (cyclosporine), narcotics (fentanyl, others), stimulants (methylphenidate), theophylline, and others.
Simvastatin (Zocor)
Interaction Rating = Moderate Be cautious with this combination.
Severity = Mild • Occurrence = Probable • Level of Evidence = B
Ginkgo extract can reduce the area under the curve and maximum concentration of simvastatin by 32% to 39%. Although it did not affect the cholesterol-lowering ability of simvastatin, theoretically, ginkgo may increase the clearance and reduce the effects of simvastatin.
Talinolol
Interaction Rating = Major Do not take this combination.
Severity = High • Occurrence = Probable • Level of Evidence = B
There is some evidence that using ginkgo leaf extract 120 mg orally three times daily for 14 days can increase levels of talinolol by 36% in healthy male individuals. However, single doses of ginkgo do not seem to affect talinolol pharmacokinetics.
Trazodone (Desyrel)
Interaction Rating = Moderate Be cautious with this combination.
Severity = High • Occurrence = Possible • Level of Evidence = D
Use of ginkgo leaf extract with trazodone has been associated with coma. In one case, an Alzheimer’s patient taking trazodone 20 mg twice daily and ginkgo leaf extract 80 mg twice daily for four doses became comatose. The coma was reversed by administration of flumazenil (Romazicon). Coma might have been induced by excessive GABA-ergic activity. Ginkgo flavonoids are thought to have GABA-ergic activity and act directly on benzodiazepine receptors. Ginkgo might also increase metabolism of trazodone to active GABA-ergic metabolites, possibly by inducing cytochrome P450 3A4 (CYP3A4) metabolism.
Warfarin (Coumadin)
Interaction Rating = Moderate Be cautious with this combination.
Severity = High • Occurrence = Possible • Level of Evidence = B
Several pharmacodynamic studies suggest that ginkgo inhibits platelet aggregation. It is thought that the ginkgo constituent, ginkgolide B, displaces platelet-activating factor (PAF) from its binding sites, decreasing blood coagulation. Several case reports have documented serious bleeding events in patients taking ginkgo. Information from a medical database suggests that when taken concurrently with warfarin, gingko increases the risk of a bleeding adverse event by 38%.There is also some evidence that ginkgo leaf extract can inhibit cytochrome P450 2C9, an enzyme that metabolizes warfarin. This could result in increased warfarin levels. However, population and clinical research has produced mixed results. Clinical research in healthy people suggests that ginkgo has no effect on INR, or the pharmacokinetics or pharmacodynamics of warfarin. A meta-analysis of 18 studies using standardized ginkgo extracts, 80 mg to 480 mg daily for up to 32 weeks, did not find a significant effect on platelet aggregation, fibrinogen concentration, or PT/aPTT. There is also some preliminary clinical research that suggests ginkgo might not significantly increase the effects of warfarin in patients that have a stable INR. Despite these negative findings, an analysis of a large medical record database suggests that gingko increases the risk of a bleeding adverse event by 38% when taken concurrently with warfarin. Until more is known, monitor INRs closely in patients taking ginkgo.
Interactions with Herbs & Supplements
Anticoagulant/Antiplatelet Herbs And Supplements:
Theoretically, concomitant use of ginkgo with other herbs and supplements that affect platelet aggregation could increase the risk of bleeding. However, the extent of ginkgo’s antiplatelet effects is questionable. There is conflicting evidence about whether ginkgo inhibits platelet aggregation. Several pharmacodynamic studies suggest that ginkgo inhibits platelet aggregation. Several case reports have also documented serious bleeding events in patients taking ginkgo. However, clinical trials and a meta-analysis evaluating standardized ginkgo leaf extracts show that the incidence of bleeding in patients taking ginkgo is not significantly higher than in those taking placebo. Until more is known, advise patients to use ginkgo cautiously if they take other herbs and supplements that affect platelet aggregation.
Some other herbs and supplements that affect platelet aggregation include angelica, clove, danshen, garlic, ginger, glucosamine, Panax ginseng, and others.
Horse Chestnut:
Ginkgo might compete with the hepatic metabolism of horse chestnut extract. Both agents are metabolized by hepatic cytochrome P450 2C9 (CYP2C9) and 3A4 (CYP3A4) isoenzymes. One case of acute renal failure requiring continuous hemodialysis has been reported in a male given gingko extract and horse chestnut tree extract injections for 16 days following fracture repair surgery. It is hypothesized that gingko might interfere with the metabolism of the horse chestnut extract, which is a known, dose-dependent nephrotoxic agent.
Seizure Threshold Lowering Herbs And Supplements:
Ginkgo seeds contain ginkgotoxin, which can cause seizures in high doses. Theoretically, patients taking supplements that also lower the seizure threshold might be at greater risk. There are anecdotal reports of seizure occurring after use of ginkgo leaf both in patients without a history seizure disorder and in those with previously well-controlled epilepsy. Advise patients taking these supplements to avoid ginkgo products. Some of these supplements include butanediol (BD), cedar leaf, Chinese club moss, EDTA, folic acid, gamma butyrolactone (GBL), gamma-hydroxybutyrate (GHB), glutamine, huperzine A, hydrazine sulfate, hyssop oil, juniper, L-carnitine, melatonin, rosemary, sage, wormwood, and others.
St. John’S Wort:
Ginkgo in combination with buspirone (BuSpar), fluoxetine (Prozac), melatonin, and St. John’s wort might cause hypomania in patients with depression. Whether ginkgo alone, or in combination with St. John’s wort, can cause hypomania is unknown.
Interactions with Foods
None known.
Interactions with Lab Tests
None known.
Interactions with Diseases
Bleeding Disorders:
Ginkgo leaf might decrease platelet aggregation by inhibiting platelet-activating factor (PAF), and thereby exacerbate bleeding disorders . However, a meta-analysis of 18 studies using standardized ginkgo extracts, 80 mg to 480 mg daily for up to 32 weeks, did not find a significant effect on bleeding risk, as measured by platelet aggregation, fibrinogen concentration, or PT/aPTT. Until more is known, use ginkgo with caution in people with bleeding disorders.
Diabetes:
- Alter insulin secretion and metabolism, and might affect blood glucose levels in people with type 2 diabetes .
- In diet-controlled diabetes patients with hyperinsulinemia, ginkgo does not affect insulin or blood glucose levels.
- In patients with hyperinsulinemia, treated with oral hypoglycemics, ginkgo seems to decrease insulin levels and increased blood glucose following an oral glucose tolerance test.
- Researchers speculate that this could be due to ginkgo-enhanced hepatic metabolism of insulin.
- In patients with pancreatic exhaustion, taking ginkgo seems to stimulate pancreatic beta-cells resulting in increased insulin and C-peptide levels, but no significant change in blood glucose levels in response to an oral glucose tolerance test. Theoretically, ginkgo might interfere with the management of diabetes. Monitor blood glucose levels closely.
Epilepsy:
Consumption of ginkgo seeds can cause seizures due to ginkgotoxin contained in the seeds. Large amounts of ginkgotoxin can cause neurotoxicity and seizure. Ginkgotoxin is present in much larger amounts in ginkgo seeds than leaves. Ginkgo leaf and ginkgo leaf extract contain trace amounts of ginkgotoxin, which can cause seizures in high doses. The amount of ginkgotoxin in ginkgo leaf and leaf extract seems unlikely to cause toxicity. However, there are several anecdotal reports of seizure occurring in patients taking combination products containing ginkgo and single ingredient ginkgo products. However, there is not yet enough evidence to prove that ginkgo can actually cause seizure in certain patients. Until more is known, use cautiously or avoid in epileptic patients or patients prone to seizure.
Glucose-6-Phosphate Dehydrogenase (G6Pd) Deficiency
A case of acute hemolytic anemia has been reported for a female patient with G6PD deficiency who received an injection of ginkgo extract 17.5 mg for dementia prophylaxis. The patient recovered following intravenous fluid treatment and cessation of ginkgo. Until more is known, use cautiously or avoid in patients with G6PD deficiency.
Infertility:
Some evidence suggests that ginkgo extract might inhibit oocyte fertilization and should be avoided in couples attempting to conceive . This effect has not yet been demonstrated in humans; however, until more is known, use with caution in couples attempting to conceive and avoid use in couples having difficulty conceiving.
Surgery:
Ginkgo biloba leaf extract has antiplatelet effects and can cause excessive bleeding if used prior to surgery. Tell patients to discontinue ginkgo at least 2 weeks before elective surgical procedures.
