People taking blood-thinning medications, those with bleeding disorders, anyone scheduled for surgery, and pregnant or breastfeeding women should not take ginkgo biloba. The supplement also carries risks for people with epilepsy or seizure disorders and those on certain antidepressants. While ginkgo is widely sold as a memory and circulation aid, it has real pharmacological effects that make it unsafe for specific groups.
People on Blood Thinners or Anti-Inflammatory Drugs
Ginkgo biloba’s most well-documented risk involves bleeding. The supplement has antiplatelet properties, meaning it makes blood cells less likely to clump together and form clots. On its own, this effect is mild. Combined with medications that also thin the blood or reduce clotting, it can become dangerous.
The medications most frequently involved in problematic interactions include aspirin, clopidogrel (Plavix), direct oral anticoagulants, warfarin, and common anti-inflammatory painkillers like celecoxib and loxoprofen. A comprehensive analysis published in PLOS One found that ginkgo interacted predominantly with antiplatelet drugs, anticoagulants, and NSAIDs, with case reports linking ginkgo use to severe bleeding events including intracranial bleeding. If you take any of these medications regularly, even over-the-counter aspirin or ibuprofen, adding ginkgo increases your bleeding risk in a way that’s difficult to predict.
People With Bleeding Disorders
Even without blood-thinning medications in the picture, people who have bleeding disorders should avoid ginkgo. The same antiplatelet activity that creates drug interactions can worsen conditions where the blood already struggles to clot properly. This includes hemophilia and other inherited or acquired clotting factor deficiencies.
Anyone Scheduled for Surgery
The American Society of Anesthesiologists and the American Association of Nurse Anesthetists recommend stopping all herbal medications one to two weeks before elective surgical procedures. Ginkgo is one of the primary reasons for this guideline. Its antiplatelet effects can cause excessive bleeding during and after surgery, and it may also interact with anesthetic medications. If you have a procedure coming up, tell your surgical team about any ginkgo use, even if you’ve already stopped taking it.
People With Epilepsy or Seizure Disorders
Ginkgo contains a compound called ginkgotoxin that can lower your seizure threshold. This toxin works by interfering with vitamin B6 in the body. Vitamin B6 is essential for producing GABA, the brain’s main calming chemical. When ginkgotoxin blocks B6, GABA production drops and the balance between excitatory and inhibitory brain activity tips toward excitation, raising the risk of seizures.
This risk is highest with ginkgo seeds (sometimes eaten as a food in East Asian cuisines), which contain far more ginkgotoxin than leaf extracts. But even standardized leaf supplements contain trace amounts. For someone with epilepsy or a history of seizures, any additional factor that lowers the seizure threshold is worth avoiding. The elderly are particularly vulnerable, as documented in case reports of seizures following ginkgo overconsumption.
Pregnant and Breastfeeding Women
Ginkgo should be avoided during pregnancy, especially in the later stages and around labor. Its antiplatelet properties could prolong bleeding time during delivery, posing risks to both mother and baby. There is also low-level evidence suggesting ginkgo may have hormonal properties and could act as an emmenagogue, a substance that stimulates menstrual flow.
Animal studies paint a more detailed picture of potential harm. When pregnant rats were given ginkgo extracts during the period equivalent to later pregnancy in humans, researchers observed significant decreases in fetal weight, indicating growth restriction in the womb. One study using commercially available ginkgo capsules at higher doses found a high frequency of malformations in mouse offspring, including abnormalities of the eyes, ears, nostrils, lips, and jaws. Sperm abnormalities were also reported in the male offspring of rats exposed to ginkgo during late pregnancy. While animal studies don’t translate directly to humans, the pattern of reproductive harm across multiple studies is concerning enough that avoidance is the standard recommendation.
During breastfeeding, the safety of ginkgo is simply unknown. No high-quality human studies have evaluated whether ginkgo compounds pass into breast milk or what effects they might have on a nursing infant.
People Taking Certain Antidepressants
If you take an SSRI antidepressant (citalopram, escitalopram, fluoxetine, fluvoxamine, sertraline) or the SNRI venlafaxine, combining it with ginkgo increases your risk of bleeding. Both SSRIs and ginkgo independently affect platelet function, so taking them together compounds the effect. This interaction has been documented across multiple SSRI medications.
For people taking bupropion (Wellbutrin), the picture is more nuanced. Lab studies using liver enzymes showed that ginkgo compounds could block one of the pathways the body uses to process bupropion. However, a human study in which young men took bupropion alongside ginkgo for 14 days found no significant changes in how the drug was metabolized. The clinical significance appears limited, but the theoretical concern exists.
People Managing Diabetes With Medication
Ginkgo has been shown to lower blood sugar levels in both animal studies and some human research. In obese rats, ginkgo extract significantly reduced blood glucose and protected against hyperglycemia. Human studies have suggested it may stimulate insulin production from the pancreas and reduce long-term blood sugar markers. These effects sound beneficial on their own, but they become a problem when layered on top of diabetes medications that are already calibrated to lower blood sugar. The combination could push glucose levels too low, causing hypoglycemia. If you take insulin or oral diabetes medications, adding ginkgo without medical supervision could destabilize your blood sugar control.
People With Ginkgo Fruit Allergies
The fleshy outer layer of ginkgo fruit contains ginkgolic acids, which are structurally similar to the irritants found in poison ivy, poison oak, and cashew shells. These compounds can cause allergic contact dermatitis, ranging from mild rash to severe skin reactions. Research in guinea pigs confirmed that ginkgolic acids are potent sensitizers. Standardized ginkgo leaf extracts are processed to contain very low levels of ginkgolic acids (the pharmaceutical-grade EGb 761 extract contains just 0.4 parts per million), but cheaper or less regulated products may contain more. If you’ve had skin reactions to ginkgo fruit or are highly sensitive to poison ivy, exercise caution.
Ginkgo Seeds vs. Leaf Extracts
Not all ginkgo products carry the same level of risk. The standardized leaf extract sold as a supplement is very different from raw or roasted ginkgo seeds eaten as food. Seeds contain much higher concentrations of ginkgotoxin, the compound responsible for seizures and vitamin B6 depletion. Standardized pharmaceutical-grade leaf extracts are manufactured to minimize toxic compounds while concentrating the active flavonoids and terpenoids.
That said, the supplement market is not uniform. One clinical study found that standardized EGb 761 extract had no significant effect on the body’s major drug-metabolizing liver enzymes, suggesting a relatively clean interaction profile at that specific formulation level. But commercially available ginkgo capsules from general retailers showed more concerning effects in animal studies, including reproductive toxicity. The quality and composition of what you’re actually taking matters enormously, and “ginkgo biloba” on a label tells you very little about the concentration of harmful compounds inside.